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/* |
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* %W% %E% |
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* |
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* Copyright 2004 Sun Microsystems, Inc. All rights reserved. |
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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*/ |
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package java.lang; |
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|
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import java.io.*; |
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import java.util.Properties; |
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import java.util.PropertyPermission; |
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import java.util.StringTokenizer; |
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import java.security.AccessController; |
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import java.security.PrivilegedAction; |
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import java.security.AllPermission; |
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import java.nio.channels.Channel; |
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import java.nio.channels.spi.SelectorProvider; |
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import sun.net.InetAddressCachePolicy; |
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import sun.reflect.Reflection; |
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import sun.security.util.SecurityConstants; |
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import sun.reflect.annotation.AnnotationType; |
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|
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/** |
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* The <code>System</code> class contains several useful class fields |
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* and methods. It cannot be instantiated. |
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* |
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* <p>Among the facilities provided by the <code>System</code> class |
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* are standard input, standard output, and error output streams; |
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* access to externally defined properties and environment |
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* variables; a means of loading files and libraries; and a utility |
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* method for quickly copying a portion of an array. |
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* |
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* @author unascribed |
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* @version %I%, %G% |
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* @since JDK1.0 |
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*/ |
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public final class System { |
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|
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/* First thing---register the natives */ |
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private static native void registerNatives(); |
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static { |
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registerNatives(); |
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} |
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|
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/** Don't let anyone instantiate this class */ |
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private System() { |
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} |
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|
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/** |
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* The "standard" input stream. This stream is already |
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* open and ready to supply input data. Typically this stream |
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* corresponds to keyboard input or another input source specified by |
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* the host environment or user. |
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*/ |
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public final static InputStream in = nullInputStream(); |
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|
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/** |
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* The "standard" output stream. This stream is already |
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* open and ready to accept output data. Typically this stream |
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* corresponds to display output or another output destination |
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* specified by the host environment or user. |
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* <p> |
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* For simple stand-alone Java applications, a typical way to write |
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* a line of output data is: |
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* <blockquote><pre> |
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* System.out.println(data) |
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* </pre></blockquote> |
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* <p> |
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* See the <code>println</code> methods in class <code>PrintStream</code>. |
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* |
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* @see java.io.PrintStream#println() |
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* @see java.io.PrintStream#println(boolean) |
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* @see java.io.PrintStream#println(char) |
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* @see java.io.PrintStream#println(char[]) |
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* @see java.io.PrintStream#println(double) |
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* @see java.io.PrintStream#println(float) |
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* @see java.io.PrintStream#println(int) |
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* @see java.io.PrintStream#println(long) |
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* @see java.io.PrintStream#println(java.lang.Object) |
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* @see java.io.PrintStream#println(java.lang.String) |
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*/ |
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public final static PrintStream out = nullPrintStream(); |
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|
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/** |
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* The "standard" error output stream. This stream is already |
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* open and ready to accept output data. |
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* <p> |
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* Typically this stream corresponds to display output or another |
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* output destination specified by the host environment or user. By |
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* convention, this output stream is used to display error messages |
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* or other information that should come to the immediate attention |
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* of a user even if the principal output stream, the value of the |
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* variable <code>out</code>, has been redirected to a file or other |
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* destination that is typically not continuously monitored. |
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*/ |
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public final static PrintStream err = nullPrintStream(); |
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|
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/* The security manager for the system. |
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*/ |
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private static SecurityManager security = null; |
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|
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/** |
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* Reassigns the "standard" input stream. |
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* |
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* <p>First, if there is a security manager, its <code>checkPermission</code> |
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* method is called with a <code>RuntimePermission("setIO")</code> permission |
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* to see if it's ok to reassign the "standard" input stream. |
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* <p> |
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* |
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* @param in the new standard input stream. |
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* |
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* @throws SecurityException |
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* if a security manager exists and its |
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* <code>checkPermission</code> method doesn't allow |
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* reassigning of the standard input stream. |
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* |
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* @see SecurityManager#checkPermission |
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* @see java.lang.RuntimePermission |
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* |
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* @since JDK1.1 |
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*/ |
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public static void setIn(InputStream in) { |
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checkIO(); |
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setIn0(in); |
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} |
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|
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/** |
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* Reassigns the "standard" output stream. |
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* |
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* <p>First, if there is a security manager, its <code>checkPermission</code> |
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* method is called with a <code>RuntimePermission("setIO")</code> permission |
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* to see if it's ok to reassign the "standard" output stream. |
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* |
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* @param out the new standard output stream |
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* |
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* @throws SecurityException |
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* if a security manager exists and its |
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* <code>checkPermission</code> method doesn't allow |
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* reassigning of the standard output stream. |
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* |
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* @see SecurityManager#checkPermission |
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* @see java.lang.RuntimePermission |
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* |
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* @since JDK1.1 |
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*/ |
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public static void setOut(PrintStream out) { |
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checkIO(); |
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setOut0(out); |
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} |
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|
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/** |
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* Reassigns the "standard" error output stream. |
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* |
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* <p>First, if there is a security manager, its <code>checkPermission</code> |
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* method is called with a <code>RuntimePermission("setIO")</code> permission |
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* to see if it's ok to reassign the "standard" error output stream. |
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* |
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* @param err the new standard error output stream. |
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* |
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* @throws SecurityException |
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* if a security manager exists and its |
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* <code>checkPermission</code> method doesn't allow |
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* reassigning of the standard error output stream. |
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* |
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* @see SecurityManager#checkPermission |
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* @see java.lang.RuntimePermission |
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* |
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* @since JDK1.1 |
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*/ |
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public static void setErr(PrintStream err) { |
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checkIO(); |
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setErr0(err); |
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} |
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|
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|
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/** |
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* Returns the channel inherited from the entity that created this |
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* Java virtual machine. |
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* |
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* <p> This method returns the channel obtained by invoking the |
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* {@link java.nio.channels.spi.SelectorProvider#inheritedChannel |
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* inheritedChannel} method of the system-wide default |
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* {@link java.nio.channels.spi.SelectorProvider} object. </p> |
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* |
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* <p> In addition to the network-oriented channels described in |
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* {@link java.nio.channels.spi.SelectorProvider#inheritedChannel |
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* inheritedChannel}, this method may return other kinds of |
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* channels in the future. |
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* |
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* @return The inherited channel, if any, otherwise <tt>null</tt>. |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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* |
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* @throws SecurityException |
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* If a security manager is present and it does not |
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* permit access to the channel. |
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* |
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* @since 1.5 |
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*/ |
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public static Channel inheritedChannel() throws IOException { |
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return SelectorProvider.provider().inheritedChannel(); |
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} |
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|
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private static void checkIO() { |
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if (security != null) |
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security.checkPermission(new RuntimePermission("setIO")); |
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} |
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|
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private static native void setIn0(InputStream in); |
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private static native void setOut0(PrintStream out); |
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private static native void setErr0(PrintStream err); |
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|
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/** |
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* Sets the System security. |
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* |
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* <p> If there is a security manager already installed, this method first |
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* calls the security manager's <code>checkPermission</code> method |
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* with a <code>RuntimePermission("setSecurityManager")</code> |
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* permission to ensure it's ok to replace the existing |
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* security manager. |
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* This may result in throwing a <code>SecurityException</code>. |
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* |
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* <p> Otherwise, the argument is established as the current |
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* security manager. If the argument is <code>null</code> and no |
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* security manager has been established, then no action is taken and |
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* the method simply returns. |
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* |
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* @param s the security manager. |
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* @exception SecurityException if the security manager has already |
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* been set and its <code>checkPermission</code> method |
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* doesn't allow it to be replaced. |
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* @see #getSecurityManager |
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* @see SecurityManager#checkPermission |
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* @see java.lang.RuntimePermission |
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*/ |
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public static |
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void setSecurityManager(final SecurityManager s) { |
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try { |
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s.checkPackageAccess("java.lang"); |
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} catch (Exception e) { |
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// no-op |
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} |
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setSecurityManager0(s); |
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} |
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|
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private static synchronized |
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void setSecurityManager0(final SecurityManager s) { |
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if (security != null) { |
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// ask the currently installed security manager if we |
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// can replace it. |
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security.checkPermission(new RuntimePermission |
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("setSecurityManager")); |
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} |
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|
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if ((s != null) && (s.getClass().getClassLoader() != null)) { |
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// New security manager class is not on bootstrap classpath. |
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// Cause policy to get initialized before we install the new |
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// security manager, in order to prevent infinite loops when |
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// trying to initialize the policy (which usually involves |
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// accessing some security and/or system properties, which in turn |
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// calls the installed security manager's checkPermission method |
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// which will loop infinitely if there is a non-system class |
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// (in this case: the new security manager class) on the stack). |
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AccessController.doPrivileged(new PrivilegedAction() { |
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public Object run() { |
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s.getClass().getProtectionDomain().implies |
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(SecurityConstants.ALL_PERMISSION); |
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return null; |
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} |
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}); |
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} |
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|
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security = s; |
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InetAddressCachePolicy.setIfNotSet(InetAddressCachePolicy.FOREVER); |
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} |
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|
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/** |
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* Gets the system security interface. |
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* |
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* @return if a security manager has already been established for the |
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* current application, then that security manager is returned; |
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* otherwise, <code>null</code> is returned. |
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* @see #setSecurityManager |
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*/ |
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public static SecurityManager getSecurityManager() { |
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return security; |
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} |
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|
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/** |
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* Returns the current time in milliseconds. Note that |
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* while the unit of time of the return value is a millisecond, |
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* the granularity of the value depends on the underlying |
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* operating system and may be larger. For example, many |
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* operating systems measure time in units of tens of |
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* milliseconds. |
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* |
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* <p> See the description of the class <code>Date</code> for |
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* a discussion of slight discrepancies that may arise between |
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* "computer time" and coordinated universal time (UTC). |
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* |
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* @return the difference, measured in milliseconds, between |
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* the current time and midnight, January 1, 1970 UTC. |
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* @see java.util.Date |
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*/ |
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public static native long currentTimeMillis(); |
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|
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/** |
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* Returns the current value of the most precise available system |
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* timer, in nanoseconds. |
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* |
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* <p>This method can only be used to measure elapsed time and is |
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* not related to any other notion of system or wall-clock time. |
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* The value returned represents nanoseconds since some fixed but |
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* arbitrary time (perhaps in the future, so values may be |
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* negative). This method provides nanosecond precision, but not |
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* necessarily nanosecond accuracy. No guarantees are made about |
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* how frequently values change. Differences in successive calls |
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* that span greater than approximately 292 years (2<sup>63</sup> |
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* nanoseconds) will not accurately compute elapsed time due to |
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* numerical overflow. |
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* |
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* <p> For example, to measure how long some code takes to execute: |
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* <pre> |
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* long startTime = System.nanoTime(); |
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* // ... the code being measured ... |
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* long estimatedTime = System.nanoTime() - startTime; |
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* </pre> |
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* |
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* @return The current value of the system timer, in nanoseconds. |
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* @since 1.5 |
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*/ |
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public static native long nanoTime(); |
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|
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/** |
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* Copies an array from the specified source array, beginning at the |
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* specified position, to the specified position of the destination array. |
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* A subsequence of array components are copied from the source |
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* array referenced by <code>src</code> to the destination array |
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* referenced by <code>dest</code>. The number of components copied is |
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* equal to the <code>length</code> argument. The components at |
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* positions <code>srcPos</code> through |
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* <code>srcPos+length-1</code> in the source array are copied into |
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* positions <code>destPos</code> through |
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* <code>destPos+length-1</code>, respectively, of the destination |
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* array. |
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* <p> |
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* If the <code>src</code> and <code>dest</code> arguments refer to the |
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* same array object, then the copying is performed as if the |
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* components at positions <code>srcPos</code> through |
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* <code>srcPos+length-1</code> were first copied to a temporary |
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* array with <code>length</code> components and then the contents of |
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* the temporary array were copied into positions |
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* <code>destPos</code> through <code>destPos+length-1</code> of the |
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* destination array. |
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* <p> |
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* If <code>dest</code> is <code>null</code>, then a |
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* <code>NullPointerException</code> is thrown. |
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* <p> |
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* If <code>src</code> is <code>null</code>, then a |
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* <code>NullPointerException</code> is thrown and the destination |
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* array is not modified. |
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* <p> |
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* Otherwise, if any of the following is true, an |
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* <code>ArrayStoreException</code> is thrown and the destination is |
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* not modified: |
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* <ul> |
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* <li>The <code>src</code> argument refers to an object that is not an |
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* array. |
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* <li>The <code>dest</code> argument refers to an object that is not an |
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* array. |
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* <li>The <code>src</code> argument and <code>dest</code> argument refer |
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* to arrays whose component types are different primitive types. |
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* <li>The <code>src</code> argument refers to an array with a primitive |
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* component type and the <code>dest</code> argument refers to an array |
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* with a reference component type. |
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* <li>The <code>src</code> argument refers to an array with a reference |
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* component type and the <code>dest</code> argument refers to an array |
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* with a primitive component type. |
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* </ul> |
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* <p> |
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* Otherwise, if any of the following is true, an |
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* <code>IndexOutOfBoundsException</code> is |
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* thrown and the destination is not modified: |
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* <ul> |
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* <li>The <code>srcPos</code> argument is negative. |
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* <li>The <code>destPos</code> argument is negative. |
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* <li>The <code>length</code> argument is negative. |
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* <li><code>srcPos+length</code> is greater than |
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* <code>src.length</code>, the length of the source array. |
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* <li><code>destPos+length</code> is greater than |
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* <code>dest.length</code>, the length of the destination array. |
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* </ul> |
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* <p> |
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* Otherwise, if any actual component of the source array from |
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* position <code>srcPos</code> through |
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* <code>srcPos+length-1</code> cannot be converted to the component |
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* type of the destination array by assignment conversion, an |
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* <code>ArrayStoreException</code> is thrown. In this case, let |
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* <b><i>k</i></b> be the smallest nonnegative integer less than |
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* length such that <code>src[srcPos+</code><i>k</i><code>]</code> |
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* cannot be converted to the component type of the destination |
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* array; when the exception is thrown, source array components from |
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* positions <code>srcPos</code> through |
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* <code>srcPos+</code><i>k</i><code>-1</code> |
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* will already have been copied to destination array positions |
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* <code>destPos</code> through |
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* <code>destPos+</code><i>k</I><code>-1</code> and no other |
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* positions of the destination array will have been modified. |
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* (Because of the restrictions already itemized, this |
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* paragraph effectively applies only to the situation where both |
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* arrays have component types that are reference types.) |
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* |
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* @param src the source array. |
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* @param srcPos starting position in the source array. |
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* @param dest the destination array. |
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* @param destPos starting position in the destination data. |
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* @param length the number of array elements to be copied. |
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* @exception IndexOutOfBoundsException if copying would cause |
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* access of data outside array bounds. |
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* @exception ArrayStoreException if an element in the <code>src</code> |
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* array could not be stored into the <code>dest</code> array |
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* because of a type mismatch. |
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* @exception NullPointerException if either <code>src</code> or |
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* <code>dest</code> is <code>null</code>. |
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*/ |
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public static native void arraycopy(Object src, int srcPos, |
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Object dest, int destPos, |
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int length); |
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|
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/** |
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* Returns the same hash code for the given object as |
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* would be returned by the default method hashCode(), |
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* whether or not the given object's class overrides |
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* hashCode(). |
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* The hash code for the null reference is zero. |
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* |
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* @param x object for which the hashCode is to be calculated |
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* @return the hashCode |
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* @since JDK1.1 |
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*/ |
442 |
public static native int identityHashCode(Object x); |
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|
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/** |
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* System properties. The following properties are guaranteed to be defined: |
446 |
* <dl> |
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* <dt>java.version <dd>Java version number |
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* <dt>java.vendor <dd>Java vendor specific string |
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* <dt>java.vendor.url <dd>Java vendor URL |
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* <dt>java.home <dd>Java installation directory |
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* <dt>java.class.version <dd>Java class version number |
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* <dt>java.class.path <dd>Java classpath |
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* <dt>os.name <dd>Operating System Name |
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* <dt>os.arch <dd>Operating System Architecture |
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* <dt>os.version <dd>Operating System Version |
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* <dt>file.separator <dd>File separator ("/" on Unix) |
457 |
* <dt>path.separator <dd>Path separator (":" on Unix) |
458 |
* <dt>line.separator <dd>Line separator ("\n" on Unix) |
459 |
* <dt>user.name <dd>User account name |
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* <dt>user.home <dd>User home directory |
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* <dt>user.dir <dd>User's current working directory |
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* </dl> |
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*/ |
464 |
|
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private static Properties props; |
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private static native Properties initProperties(Properties props); |
467 |
|
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/** |
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* Determines the current system properties. |
470 |
* <p> |
471 |
* First, if there is a security manager, its |
472 |
* <code>checkPropertiesAccess</code> method is called with no |
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* arguments. This may result in a security exception. |
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* <p> |
475 |
* The current set of system properties for use by the |
476 |
* {@link #getProperty(String)} method is returned as a |
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* <code>Properties</code> object. If there is no current set of |
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* system properties, a set of system properties is first created and |
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* initialized. This set of system properties always includes values |
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* for the following keys: |
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* <table summary="Shows property keys and associated values"> |
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* <tr><th>Key</th> |
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* <th>Description of Associated Value</th></tr> |
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* <tr><td><code>java.version</code></td> |
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* <td>Java Runtime Environment version</td></tr> |
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* <tr><td><code>java.vendor</code></td> |
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* <td>Java Runtime Environment vendor</td></tr |
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* <tr><td><code>java.vendor.url</code></td> |
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* <td>Java vendor URL</td></tr> |
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* <tr><td><code>java.home</code></td> |
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* <td>Java installation directory</td></tr> |
492 |
* <tr><td><code>java.vm.specification.version</code></td> |
493 |
* <td>Java Virtual Machine specification version</td></tr> |
494 |
* <tr><td><code>java.vm.specification.vendor</code></td> |
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* <td>Java Virtual Machine specification vendor</td></tr> |
496 |
* <tr><td><code>java.vm.specification.name</code></td> |
497 |
* <td>Java Virtual Machine specification name</td></tr> |
498 |
* <tr><td><code>java.vm.version</code></td> |
499 |
* <td>Java Virtual Machine implementation version</td></tr> |
500 |
* <tr><td><code>java.vm.vendor</code></td> |
501 |
* <td>Java Virtual Machine implementation vendor</td></tr> |
502 |
* <tr><td><code>java.vm.name</code></td> |
503 |
* <td>Java Virtual Machine implementation name</td></tr> |
504 |
* <tr><td><code>java.specification.version</code></td> |
505 |
* <td>Java Runtime Environment specification version</td></tr> |
506 |
* <tr><td><code>java.specification.vendor</code></td> |
507 |
* <td>Java Runtime Environment specification vendor</td></tr> |
508 |
* <tr><td><code>java.specification.name</code></td> |
509 |
* <td>Java Runtime Environment specification name</td></tr> |
510 |
* <tr><td><code>java.class.version</code></td> |
511 |
* <td>Java class format version number</td></tr> |
512 |
* <tr><td><code>java.class.path</code></td> |
513 |
* <td>Java class path</td></tr> |
514 |
* <tr><td><code>java.library.path</code></td> |
515 |
* <td>List of paths to search when loading libraries</td></tr> |
516 |
* <tr><td><code>java.io.tmpdir</code></td> |
517 |
* <td>Default temp file path</td></tr> |
518 |
* <tr><td><code>java.compiler</code></td> |
519 |
* <td>Name of JIT compiler to use</td></tr> |
520 |
* <tr><td><code>java.ext.dirs</code></td> |
521 |
* <td>Path of extension directory or directories</td></tr> |
522 |
* <tr><td><code>os.name</code></td> |
523 |
* <td>Operating system name</td></tr> |
524 |
* <tr><td><code>os.arch</code></td> |
525 |
* <td>Operating system architecture</td></tr> |
526 |
* <tr><td><code>os.version</code></td> |
527 |
* <td>Operating system version</td></tr> |
528 |
* <tr><td><code>file.separator</code></td> |
529 |
* <td>File separator ("/" on UNIX)</td></tr> |
530 |
* <tr><td><code>path.separator</code></td> |
531 |
* <td>Path separator (":" on UNIX)</td></tr> |
532 |
* <tr><td><code>line.separator</code></td> |
533 |
* <td>Line separator ("\n" on UNIX)</td></tr> |
534 |
* <tr><td><code>user.name</code></td> |
535 |
* <td>User's account name</td></tr> |
536 |
* <tr><td><code>user.home</code></td> |
537 |
* <td>User's home directory</td></tr> |
538 |
* <tr><td><code>user.dir</code></td> |
539 |
* <td>User's current working directory</td></tr> |
540 |
* </table> |
541 |
* <p> |
542 |
* Multiple paths in a system property value are separated by the path |
543 |
* separator character of the platform. |
544 |
* <p> |
545 |
* Note that even if the security manager does not permit the |
546 |
* <code>getProperties</code> operation, it may choose to permit the |
547 |
* {@link #getProperty(String)} operation. |
548 |
* |
549 |
* @return the system properties |
550 |
* @exception SecurityException if a security manager exists and its |
551 |
* <code>checkPropertiesAccess</code> method doesn't allow access |
552 |
* to the system properties. |
553 |
* @see #setProperties |
554 |
* @see java.lang.SecurityException |
555 |
* @see java.lang.SecurityManager#checkPropertiesAccess() |
556 |
* @see java.util.Properties |
557 |
*/ |
558 |
public static Properties getProperties() { |
559 |
if (security != null) { |
560 |
security.checkPropertiesAccess(); |
561 |
} |
562 |
return props; |
563 |
} |
564 |
|
565 |
/** |
566 |
* Sets the system properties to the <code>Properties</code> |
567 |
* argument. |
568 |
* <p> |
569 |
* First, if there is a security manager, its |
570 |
* <code>checkPropertiesAccess</code> method is called with no |
571 |
* arguments. This may result in a security exception. |
572 |
* <p> |
573 |
* The argument becomes the current set of system properties for use |
574 |
* by the {@link #getProperty(String)} method. If the argument is |
575 |
* <code>null</code>, then the current set of system properties is |
576 |
* forgotten. |
577 |
* |
578 |
* @param props the new system properties. |
579 |
* @exception SecurityException if a security manager exists and its |
580 |
* <code>checkPropertiesAccess</code> method doesn't allow access |
581 |
* to the system properties. |
582 |
* @see #getProperties |
583 |
* @see java.util.Properties |
584 |
* @see java.lang.SecurityException |
585 |
* @see java.lang.SecurityManager#checkPropertiesAccess() |
586 |
*/ |
587 |
public static void setProperties(Properties props) { |
588 |
if (security != null) { |
589 |
security.checkPropertiesAccess(); |
590 |
} |
591 |
if (props == null) { |
592 |
props = new Properties(); |
593 |
initProperties(props); |
594 |
} |
595 |
System.props = props; |
596 |
} |
597 |
|
598 |
/** |
599 |
* Gets the system property indicated by the specified key. |
600 |
* <p> |
601 |
* First, if there is a security manager, its |
602 |
* <code>checkPropertyAccess</code> method is called with the key as |
603 |
* its argument. This may result in a SecurityException. |
604 |
* <p> |
605 |
* If there is no current set of system properties, a set of system |
606 |
* properties is first created and initialized in the same manner as |
607 |
* for the <code>getProperties</code> method. |
608 |
* |
609 |
* @param key the name of the system property. |
610 |
* @return the string value of the system property, |
611 |
* or <code>null</code> if there is no property with that key. |
612 |
* |
613 |
* @exception SecurityException if a security manager exists and its |
614 |
* <code>checkPropertyAccess</code> method doesn't allow |
615 |
* access to the specified system property. |
616 |
* @exception NullPointerException if <code>key</code> is |
617 |
* <code>null</code>. |
618 |
* @exception IllegalArgumentException if <code>key</code> is empty. |
619 |
* @see #setProperty |
620 |
* @see java.lang.SecurityException |
621 |
* @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String) |
622 |
* @see java.lang.System#getProperties() |
623 |
*/ |
624 |
public static String getProperty(String key) { |
625 |
checkKey(key); |
626 |
if (security != null) { |
627 |
security.checkPropertyAccess(key); |
628 |
} |
629 |
return props.getProperty(key); |
630 |
} |
631 |
|
632 |
/** |
633 |
* Gets the system property indicated by the specified key. |
634 |
* <p> |
635 |
* First, if there is a security manager, its |
636 |
* <code>checkPropertyAccess</code> method is called with the |
637 |
* <code>key</code> as its argument. |
638 |
* <p> |
639 |
* If there is no current set of system properties, a set of system |
640 |
* properties is first created and initialized in the same manner as |
641 |
* for the <code>getProperties</code> method. |
642 |
* |
643 |
* @param key the name of the system property. |
644 |
* @param def a default value. |
645 |
* @return the string value of the system property, |
646 |
* or the default value if there is no property with that key. |
647 |
* |
648 |
* @exception SecurityException if a security manager exists and its |
649 |
* <code>checkPropertyAccess</code> method doesn't allow |
650 |
* access to the specified system property. |
651 |
* @exception NullPointerException if <code>key</code> is |
652 |
* <code>null</code>. |
653 |
* @exception IllegalArgumentException if <code>key</code> is empty. |
654 |
* @see #setProperty |
655 |
* @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String) |
656 |
* @see java.lang.System#getProperties() |
657 |
*/ |
658 |
public static String getProperty(String key, String def) { |
659 |
checkKey(key); |
660 |
if (security != null) { |
661 |
security.checkPropertyAccess(key); |
662 |
} |
663 |
return props.getProperty(key, def); |
664 |
} |
665 |
|
666 |
/** |
667 |
* Sets the system property indicated by the specified key. |
668 |
* <p> |
669 |
* First, if a security manager exists, its |
670 |
* <code>SecurityManager.checkPermission</code> method |
671 |
* is called with a <code>PropertyPermission(key, "write")</code> |
672 |
* permission. This may result in a SecurityException being thrown. |
673 |
* If no exception is thrown, the specified property is set to the given |
674 |
* value. |
675 |
* <p> |
676 |
* |
677 |
* @param key the name of the system property. |
678 |
* @param value the value of the system property. |
679 |
* @return the previous value of the system property, |
680 |
* or <code>null</code> if it did not have one. |
681 |
* |
682 |
* @exception SecurityException if a security manager exists and its |
683 |
* <code>checkPermission</code> method doesn't allow |
684 |
* setting of the specified property. |
685 |
* @exception NullPointerException if <code>key</code> or |
686 |
* <code>value</code> is <code>null</code>. |
687 |
* @exception IllegalArgumentException if <code>key</code> is empty. |
688 |
* @see #getProperty |
689 |
* @see java.lang.System#getProperty(java.lang.String) |
690 |
* @see java.lang.System#getProperty(java.lang.String, java.lang.String) |
691 |
* @see java.util.PropertyPermission |
692 |
* @see SecurityManager#checkPermission |
693 |
* @since 1.2 |
694 |
*/ |
695 |
public static String setProperty(String key, String value) { |
696 |
checkKey(key); |
697 |
if (security != null) |
698 |
security.checkPermission(new PropertyPermission(key, |
699 |
SecurityConstants.PROPERTY_WRITE_ACTION)); |
700 |
return (String) props.setProperty(key, value); |
701 |
} |
702 |
|
703 |
/** |
704 |
* Removes the system property indicated by the specified key. |
705 |
* <p> |
706 |
* First, if a security manager exists, its |
707 |
* <code>SecurityManager.checkPermission</code> method |
708 |
* is called with a <code>PropertyPermission(key, "write")</code> |
709 |
* permission. This may result in a SecurityException being thrown. |
710 |
* If no exception is thrown, the specified property is removed. |
711 |
* <p> |
712 |
* |
713 |
* @param key the name of the system property to be removed. |
714 |
* @return the previous string value of the system property, |
715 |
* or <code>null</code> if there was no property with that key. |
716 |
* |
717 |
* @exception SecurityException if a security manager exists and its |
718 |
* <code>checkPropertyAccess</code> method doesn't allow |
719 |
* access to the specified system property. |
720 |
* @exception NullPointerException if <code>key</code> is |
721 |
* <code>null</code>. |
722 |
* @exception IllegalArgumentException if <code>key</code> is empty. |
723 |
* @see #getProperty |
724 |
* @see #setProperty |
725 |
* @see java.util.Properties |
726 |
* @see java.lang.SecurityException |
727 |
* @see java.lang.SecurityManager#checkPropertiesAccess() |
728 |
* @since 1.5 |
729 |
*/ |
730 |
public static String clearProperty(String key) { |
731 |
checkKey(key); |
732 |
if (security != null) |
733 |
security.checkPermission(new PropertyPermission(key, "write")); |
734 |
return (String) props.remove(key); |
735 |
} |
736 |
|
737 |
private static void checkKey(String key) { |
738 |
if (key == null) { |
739 |
throw new NullPointerException("key can't be null"); |
740 |
} |
741 |
if (key.equals("")) { |
742 |
throw new IllegalArgumentException("key can't be empty"); |
743 |
} |
744 |
} |
745 |
|
746 |
/** |
747 |
* Gets the value of the specified environment variable. An |
748 |
* environment variable is a system-dependent external named |
749 |
* value. |
750 |
* |
751 |
* <p>If a security manager exists, its |
752 |
* {@link SecurityManager#checkPermission checkPermission} |
753 |
* method is called with a |
754 |
* <code>{@link RuntimePermission}("getenv."+name)</code> |
755 |
* permission. This may result in a {@link SecurityException} |
756 |
* being thrown. If no exception is thrown the value of the |
757 |
* variable <code>name</code> is returned. |
758 |
* |
759 |
* <p><a name="EnvironmentVSSystemProperties"><i>System |
760 |
* properties</i> and <i>environment variables</i> are both |
761 |
* conceptually mappings between names and values. Both |
762 |
* mechanisms can be used to pass user-defined information to a |
763 |
* Java process. Environment variables have a more global effect, |
764 |
* because they are visible to all descendants of the process |
765 |
* which defines them, not just the immediate Java subprocess. |
766 |
* They can have subtly different semantics, such as case |
767 |
* insensitivity, on different operating systems. For these |
768 |
* reasons, environment variables are more likely to have |
769 |
* unintended side effects. It is best to use system properties |
770 |
* where possible. Environment variables should be used when a |
771 |
* global effect is desired, or when an external system interface |
772 |
* requires an environment variable (such as <code>PATH</code>). |
773 |
* |
774 |
* <p>On UNIX systems the alphabetic case of <code>name</code> is |
775 |
* typically significant, while on Microsoft Windows systems it is |
776 |
* typically not. For example, the expression |
777 |
* <code>System.getenv("FOO").equals(System.getenv("foo"))</code> |
778 |
* is likely to be true on Microsoft Windows. |
779 |
* |
780 |
* @param name the name of the environment variable |
781 |
* @return the string value of the variable, or <code>null</code> |
782 |
* if the variable is not defined in the system environment |
783 |
* @throws NullPointerException if <code>name</code> is <code>null</code> |
784 |
* @throws SecurityException |
785 |
* if a security manager exists and its |
786 |
* {@link SecurityManager#checkPermission checkPermission} |
787 |
* method doesn't allow access to the environment variable |
788 |
* <code>name</code> |
789 |
* @see #getenv() |
790 |
* @see ProcessBuilder#environment() |
791 |
*/ |
792 |
public static String getenv(String name) { |
793 |
if (security != null) |
794 |
security.checkPermission(new RuntimePermission("getenv."+name)); |
795 |
|
796 |
return ProcessEnvironment.getenv(name); |
797 |
} |
798 |
|
799 |
|
800 |
/** |
801 |
* Returns an unmodifiable string map view of the current system environment. |
802 |
* The environment is a system-dependent mapping from names to |
803 |
* values which is passed from parent to child processes. |
804 |
* |
805 |
* <p>If the system does not support environment variables, an |
806 |
* empty map is returned. |
807 |
* |
808 |
* <p>The returned map will never contain null keys or values. |
809 |
* Attempting to query the presence of a null key or value will |
810 |
* throw a {@link NullPointerException}. Attempting to query |
811 |
* the presence of a key or value which is not of type |
812 |
* {@link String} will throw a {@link ClassCastException}. |
813 |
* |
814 |
* <p>The returned map and its collection views may not obey the |
815 |
* general contract of the {@link Object#equals} and |
816 |
* {@link Object#hashCode} methods. |
817 |
* |
818 |
* <p>The returned map is typically case-sensitive on all platforms. |
819 |
* |
820 |
* <p>If a security manager exists, its |
821 |
* {@link SecurityManager#checkPermission checkPermission} |
822 |
* method is called with a |
823 |
* <code>{@link RuntimePermission}("getenv.*")</code> |
824 |
* permission. This may result in a {@link SecurityException} being |
825 |
* thrown. |
826 |
* |
827 |
* <p>When passing information to a Java subprocess, |
828 |
* <a href=#EnvironmentVSSystemProperties>system properties</a> |
829 |
* are generally preferred over environment variables. |
830 |
* |
831 |
* @return the environment as a map of variable names to values |
832 |
* @throws SecurityException |
833 |
* if a security manager exists and its |
834 |
* {@link SecurityManager#checkPermission checkPermission} |
835 |
* method doesn't allow access to the process environment |
836 |
* @see #getenv(String) |
837 |
* @see ProcessBuilder#environment() |
838 |
* @since 1.5 |
839 |
*/ |
840 |
public static java.util.Map<String,String> getenv() { |
841 |
if (security != null) |
842 |
security.checkPermission(new RuntimePermission("getenv.*")); |
843 |
|
844 |
return ProcessEnvironment.getenv(); |
845 |
} |
846 |
|
847 |
/** |
848 |
* Terminates the currently running Java Virtual Machine. The |
849 |
* argument serves as a status code; by convention, a nonzero status |
850 |
* code indicates abnormal termination. |
851 |
* <p> |
852 |
* This method calls the <code>exit</code> method in class |
853 |
* <code>Runtime</code>. This method never returns normally. |
854 |
* <p> |
855 |
* The call <code>System.exit(n)</code> is effectively equivalent to |
856 |
* the call: |
857 |
* <blockquote><pre> |
858 |
* Runtime.getRuntime().exit(n) |
859 |
* </pre></blockquote> |
860 |
* |
861 |
* @param status exit status. |
862 |
* @throws SecurityException |
863 |
* if a security manager exists and its <code>checkExit</code> |
864 |
* method doesn't allow exit with the specified status. |
865 |
* @see java.lang.Runtime#exit(int) |
866 |
*/ |
867 |
public static void exit(int status) { |
868 |
Runtime.getRuntime().exit(status); |
869 |
} |
870 |
|
871 |
/** |
872 |
* Runs the garbage collector. |
873 |
* <p> |
874 |
* Calling the <code>gc</code> method suggests that the Java Virtual |
875 |
* Machine expend effort toward recycling unused objects in order to |
876 |
* make the memory they currently occupy available for quick reuse. |
877 |
* When control returns from the method call, the Java Virtual |
878 |
* Machine has made a best effort to reclaim space from all discarded |
879 |
* objects. |
880 |
* <p> |
881 |
* The call <code>System.gc()</code> is effectively equivalent to the |
882 |
* call: |
883 |
* <blockquote><pre> |
884 |
* Runtime.getRuntime().gc() |
885 |
* </pre></blockquote> |
886 |
* |
887 |
* @see java.lang.Runtime#gc() |
888 |
*/ |
889 |
public static void gc() { |
890 |
Runtime.getRuntime().gc(); |
891 |
} |
892 |
|
893 |
/** |
894 |
* Runs the finalization methods of any objects pending finalization. |
895 |
* <p> |
896 |
* Calling this method suggests that the Java Virtual Machine expend |
897 |
* effort toward running the <code>finalize</code> methods of objects |
898 |
* that have been found to be discarded but whose <code>finalize</code> |
899 |
* methods have not yet been run. When control returns from the |
900 |
* method call, the Java Virtual Machine has made a best effort to |
901 |
* complete all outstanding finalizations. |
902 |
* <p> |
903 |
* The call <code>System.runFinalization()</code> is effectively |
904 |
* equivalent to the call: |
905 |
* <blockquote><pre> |
906 |
* Runtime.getRuntime().runFinalization() |
907 |
* </pre></blockquote> |
908 |
* |
909 |
* @see java.lang.Runtime#runFinalization() |
910 |
*/ |
911 |
public static void runFinalization() { |
912 |
Runtime.getRuntime().runFinalization(); |
913 |
} |
914 |
|
915 |
/** |
916 |
* Enable or disable finalization on exit; doing so specifies that the |
917 |
* finalizers of all objects that have finalizers that have not yet been |
918 |
* automatically invoked are to be run before the Java runtime exits. |
919 |
* By default, finalization on exit is disabled. |
920 |
* |
921 |
* <p>If there is a security manager, |
922 |
* its <code>checkExit</code> method is first called |
923 |
* with 0 as its argument to ensure the exit is allowed. |
924 |
* This could result in a SecurityException. |
925 |
* |
926 |
* @deprecated This method is inherently unsafe. It may result in |
927 |
* finalizers being called on live objects while other threads are |
928 |
* concurrently manipulating those objects, resulting in erratic |
929 |
* behavior or deadlock. |
930 |
* @param value indicating enabling or disabling of finalization |
931 |
* @throws SecurityException |
932 |
* if a security manager exists and its <code>checkExit</code> |
933 |
* method doesn't allow the exit. |
934 |
* |
935 |
* @see java.lang.Runtime#exit(int) |
936 |
* @see java.lang.Runtime#gc() |
937 |
* @see java.lang.SecurityManager#checkExit(int) |
938 |
* @since JDK1.1 |
939 |
*/ |
940 |
@Deprecated |
941 |
public static void runFinalizersOnExit(boolean value) { |
942 |
Runtime.getRuntime().runFinalizersOnExit(value); |
943 |
} |
944 |
|
945 |
/** |
946 |
* Loads a code file with the specified filename from the local file |
947 |
* system as a dynamic library. The filename |
948 |
* argument must be a complete path name. |
949 |
* <p> |
950 |
* The call <code>System.load(name)</code> is effectively equivalent |
951 |
* to the call: |
952 |
* <blockquote><pre> |
953 |
* Runtime.getRuntime().load(name) |
954 |
* </pre></blockquote> |
955 |
* |
956 |
* @param filename the file to load. |
957 |
* @exception SecurityException if a security manager exists and its |
958 |
* <code>checkLink</code> method doesn't allow |
959 |
* loading of the specified dynamic library |
960 |
* @exception UnsatisfiedLinkError if the file does not exist. |
961 |
* @exception NullPointerException if <code>filename</code> is |
962 |
* <code>null</code> |
963 |
* @see java.lang.Runtime#load(java.lang.String) |
964 |
* @see java.lang.SecurityManager#checkLink(java.lang.String) |
965 |
*/ |
966 |
public static void load(String filename) { |
967 |
Runtime.getRuntime().load0(getCallerClass(), filename); |
968 |
} |
969 |
|
970 |
/** |
971 |
* Loads the system library specified by the <code>libname</code> |
972 |
* argument. The manner in which a library name is mapped to the |
973 |
* actual system library is system dependent. |
974 |
* <p> |
975 |
* The call <code>System.loadLibrary(name)</code> is effectively |
976 |
* equivalent to the call |
977 |
* <blockquote><pre> |
978 |
* Runtime.getRuntime().loadLibrary(name) |
979 |
* </pre></blockquote> |
980 |
* |
981 |
* @param libname the name of the library. |
982 |
* @exception SecurityException if a security manager exists and its |
983 |
* <code>checkLink</code> method doesn't allow |
984 |
* loading of the specified dynamic library |
985 |
* @exception UnsatisfiedLinkError if the library does not exist. |
986 |
* @exception NullPointerException if <code>libname</code> is |
987 |
* <code>null</code> |
988 |
* @see java.lang.Runtime#loadLibrary(java.lang.String) |
989 |
* @see java.lang.SecurityManager#checkLink(java.lang.String) |
990 |
*/ |
991 |
public static void loadLibrary(String libname) { |
992 |
Runtime.getRuntime().loadLibrary0(getCallerClass(), libname); |
993 |
} |
994 |
|
995 |
/** |
996 |
* Maps a library name into a platform-specific string representing |
997 |
* a native library. |
998 |
* |
999 |
* @param libname the name of the library. |
1000 |
* @return a platform-dependent native library name. |
1001 |
* @exception NullPointerException if <code>libname</code> is |
1002 |
* <code>null</code> |
1003 |
* @see java.lang.System#loadLibrary(java.lang.String) |
1004 |
* @see java.lang.ClassLoader#findLibrary(java.lang.String) |
1005 |
* @since 1.2 |
1006 |
*/ |
1007 |
public static native String mapLibraryName(String libname); |
1008 |
|
1009 |
/** |
1010 |
* The following two methods exist because in, out, and err must be |
1011 |
* initialized to null. The compiler, however, cannot be permitted to |
1012 |
* inline access to them, since they are later set to more sensible values |
1013 |
* by initializeSystemClass(). |
1014 |
*/ |
1015 |
private static InputStream nullInputStream() throws NullPointerException { |
1016 |
if (currentTimeMillis() > 0) |
1017 |
return null; |
1018 |
throw new NullPointerException(); |
1019 |
} |
1020 |
|
1021 |
private static PrintStream nullPrintStream() throws NullPointerException { |
1022 |
if (currentTimeMillis() > 0) |
1023 |
return null; |
1024 |
throw new NullPointerException(); |
1025 |
} |
1026 |
|
1027 |
/** |
1028 |
* Initialize the system class. Called after thread initialization. |
1029 |
*/ |
1030 |
private static void initializeSystemClass() { |
1031 |
props = new Properties(); |
1032 |
initProperties(props); |
1033 |
sun.misc.Version.init(); |
1034 |
FileInputStream fdIn = new FileInputStream(FileDescriptor.in); |
1035 |
FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out); |
1036 |
FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err); |
1037 |
setIn0(new BufferedInputStream(fdIn)); |
1038 |
setOut0(new PrintStream(new BufferedOutputStream(fdOut, 128), true)); |
1039 |
setErr0(new PrintStream(new BufferedOutputStream(fdErr, 128), true)); |
1040 |
|
1041 |
// Load the zip library now in order to keep java.util.zip.ZipFile |
1042 |
// from trying to use itself to load this library later. |
1043 |
loadLibrary("zip"); |
1044 |
|
1045 |
// Currently File.deleteOnExit is built on JVM_Exit, which is a |
1046 |
// separate mechanism from shutdown hooks. Unfortunately in order to |
1047 |
// work properly JVM_Exit implicitly requires that Java signal |
1048 |
// handlers be set up for HUP, TERM, and INT (where available). If |
1049 |
// File.deleteOnExit were implemented in terms of shutdown hooks this |
1050 |
// call to Terminator.setup() could be removed. |
1051 |
Terminator.setup(); |
1052 |
|
1053 |
// Set the maximum amount of direct memory. This value is controlled |
1054 |
// by the vm option -XX:MaxDirectMemorySize=<size>. This method acts |
1055 |
// as an initializer only if it is called before sun.misc.VM.booted(). |
1056 |
sun.misc.VM.maxDirectMemory(); |
1057 |
|
1058 |
// Set a boolean to determine whether ClassLoader.loadClass accepts |
1059 |
// array syntax. This value is controlled by the system property |
1060 |
// "sun.lang.ClassLoader.allowArraySyntax". This method acts as |
1061 |
// an initializer only if it is called before sun.misc.VM.booted(). |
1062 |
sun.misc.VM.allowArraySyntax(); |
1063 |
|
1064 |
// Subsystems that are invoked during initialization can invoke |
1065 |
// sun.misc.VM.isBooted() in order to avoid doing things that should |
1066 |
// wait until the application class loader has been set up. |
1067 |
sun.misc.VM.booted(); |
1068 |
|
1069 |
// The main thread is not added to its thread group in the same |
1070 |
// way as other threads; we must do it ourselves here. |
1071 |
Thread current = Thread.currentThread(); |
1072 |
current.getThreadGroup().add(current); |
1073 |
|
1074 |
// Allow privileged classes outside of java.lang |
1075 |
sun.misc.SharedSecrets.setJavaLangAccess(new sun.misc.JavaLangAccess(){ |
1076 |
public sun.reflect.ConstantPool getConstantPool(Class klass) { |
1077 |
return klass.getConstantPool(); |
1078 |
} |
1079 |
public void setAnnotationType(Class klass, AnnotationType type) { |
1080 |
klass.setAnnotationType(type); |
1081 |
} |
1082 |
public AnnotationType getAnnotationType(Class klass) { |
1083 |
return klass.getAnnotationType(); |
1084 |
} |
1085 |
}); |
1086 |
} |
1087 |
|
1088 |
/* returns the class of the caller. */ |
1089 |
static Class getCallerClass() { |
1090 |
// NOTE use of more generic Reflection.getCallerClass() |
1091 |
return Reflection.getCallerClass(3); |
1092 |
} |
1093 |
} |