/*
* @(#)Runtime.java 1.65 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.lang;
import java.io.*;
import java.util.StringTokenizer;
/**
* Every Java application has a single instance of class
* <code>Runtime</code> that allows the application to interface with
* the environment in which the application is running. The current
* runtime can be obtained from the <code>getRuntime</code> method.
* <p>
* An application cannot create its own instance of this class.
*
* @author unascribed
* @version 1.57, 05/03/00
* @see java.lang.Runtime#getRuntime()
* @since JDK1.0
*/
public class Runtime {
private static Runtime currentRuntime = new Runtime();
/**
* Returns the runtime object associated with the current Java application.
* Most of the methods of class <code>Runtime</code> are instance
* methods and must be invoked with respect to the current runtime object.
*
* @return the <code>Runtime</code> object associated with the current
* Java application.
*/
public static Runtime getRuntime() {
return currentRuntime;
}
/** Don't let anyone else instantiate this class */
private Runtime() {}
/**
* Terminates the currently running Java virtual machine by initiating its
* shutdown sequence. This method never returns normally. The argument
* serves as a status code; by convention, a nonzero status code indicates
* abnormal termination.
*
* <p> The virtual machine's shutdown sequence consists of two phases. In
* the first phase all registered {@link #addShutdownHook shutdown hooks},
* if any, are started in some unspecified order and allowed to run
* concurrently until they finish. In the second phase all uninvoked
* finalizers are run if finalization-on-exit
* has been enabled. Once this is done the virtual machine {@link #halt
* halts}.
*
* <p> If this method is invoked after the virtual machine has begun its
* shutdown sequence then if shutdown hooks are being run this method will
* block indefinitely. If shutdown hooks have already been run and on-exit
* finalization has been enabled then this method halts the virtual machine
* with the given status code if the status is nonzero; otherwise, it
* blocks indefinitely.
*
* <p> The <tt>{@link System#exit(int) System.exit}</tt> method is the
* conventional and convenient means of invoking this method. <p>
*
* If process model exists, Runtime.exit() must rely on the process
* exiting to release resources.
* <p>
* If process model does not exist, and a security manager exists,
* the security manager by default must prohibit calls to Runtime.exit()
* by throwing SecurityException. Otherwise, the system will hang
* indefinitely when called.
* <p>
* @param status
* Termination status. By convention, a nonzero status code
* indicates abnormal termination.
*
* @throws SecurityException
* If a security manager is present and its <tt>{@link
* SecurityManager#checkExit checkExit}</tt> method does not permit
* exiting with the specified status
*
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkExit(int)
* @see #addShutdownHook
* @see #removeShutdownHook
* @see #halt(int)
*/
public void exit(int status) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkExit(status);
}
if (!safeExit(status)) {
Shutdown.exit(status);
}
}
private static native boolean safeExit(int status);
/**
* Registers a new virtual-machine shutdown hook.
*
* <p> The Java virtual machine <i>shuts down</i> in response to two kinds
* of events:
*
* <ul>
*
* <p> <li> The program <i>exits</i> normally, when the last non-daemon
* thread exits or when the <tt>{@link #exit exit}</tt> (equivalently,
* <tt>{@link System#exit(int) System.exit}</tt>) method is invoked, or
*
* <p> <li> The virtual machine is <i>terminated</i> in response to a
* user interrupt, such as typing <tt>^C</tt>, or a system-wide event,
* such as user logoff or system shutdown.
*
* </ul>
*
* <p> A <i>shutdown hook</i> is simply an initialized but unstarted
* thread. When the virtual machine begins its shutdown sequence it will
* start all registered shutdown hooks in some unspecified order and let
* them run concurrently. When all the hooks have finished it will then
* run all uninvoked finalizers if finalization-on-exit has been enabled.
* Finally, the virtual machine will halt. Note that daemon threads will
* continue to run during the shutdown sequence, as will non-daemon threads
* if shutdown was initiated by invoking the <tt>{@link #exit exit}</tt>
* method.
*
* <p> Once the shutdown sequence has begun it can be stopped only by
* invoking the <tt>{@link #halt halt}</tt> method, which forcibly
* terminates the virtual machine.
*
* <p> Once the shutdown sequence has begun it is impossible to register a
* new shutdown hook or de-register a previously-registered hook.
* Attempting either of these operations will cause an
* <tt>{@link IllegalStateException}</tt> to be thrown.
*
* <p> Shutdown hooks run at a delicate time in the life cycle of a virtual
* machine and should therefore be coded defensively. They should, in
* particular, be written to be thread-safe and to avoid deadlocks insofar
* as possible. They should also not rely blindly upon services that may
* have registered their own shutdown hooks and therefore may themselves in
* the process of shutting down.
*
* <p> Shutdown hooks should also finish their work quickly. When a
* program invokes <tt>{@link #exit exit}</tt> the expectation is
* that the virtual machine will promptly shut down and exit. When the
* virtual machine is terminated due to user logoff or system shutdown the
* underlying operating system may only allow a fixed amount of time in
* which to shut down and exit. It is therefore inadvisable to attempt any
* user interaction or to perform a long-running computation in a shutdown
* hook.
*
* <p> Uncaught exceptions are handled in shutdown hooks just as in any
* other thread, by invoking the <tt>{@link ThreadGroup#uncaughtException
* uncaughtException}</tt> method of the thread's <tt>{@link
* ThreadGroup}</tt> object. The default implementation of this method
* prints the exception's stack trace to <tt>{@link System#err}</tt> and
* terminates the thread; it does not cause the virtual machine to exit or
* halt.
*
* <p> In rare circumstances the virtual machine may <i>abort</i>, that is,
* stop running without shutting down cleanly. This occurs when the
* virtual machine is terminated externally, for example with the
* <tt>SIGKILL</tt> signal on Unix or the <tt>TerminateProcess</tt> call on
* Microsoft Windows. The virtual machine may also abort if a native method goes awry
* by, for example, corrupting internal data structures or attempting to
* access nonexistent memory. If the virtual machine aborts then no
* guarantee can be made about whether or not any shutdown hooks will be
* run. <p>
*
* @param hook
* An initialized but unstarted <tt>{@link Thread}</tt> object
*
* @throws IllegalArgumentException
* If the specified hook has already been registered,
* or if it can be determined that the hook is already running or
* has already been run
*
* @throws IllegalStateException
* If the virtual machine is already in the process
* of shutting down
*
* @throws SecurityException
* If a security manager is present and it denies
* <tt>{@link RuntimePermission}("shutdownHooks")</tt>
*
* @see #removeShutdownHook
* @see #halt(int)
* @see #exit(int)
* @since 1.3
*/
public void addShutdownHook(Thread hook) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(new RuntimePermission("shutdownHooks"));
}
Shutdown.add(hook);
}
/**
* De-registers a previously-registered virtual-machine shutdown hook. <p>
*
* @param hook the hook to remove
* @return <tt>true</tt> if the specified hook had previously been
* registered and was successfully de-registered, <tt>false</tt>
* otherwise.
*
* @throws IllegalStateException
* If the virtual machine is already in the process of shutting
* down
*
* @throws SecurityException
* If a security manager is present and it denies
* <tt>{@link RuntimePermission}("shutdownHooks")</tt>
*
* @see #addShutdownHook
* @see #exit(int)
* @since 1.3
*/
public boolean removeShutdownHook(Thread hook) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(new RuntimePermission("shutdownHooks"));
}
return Shutdown.remove(hook);
}
/**
* Forcibly terminates the currently running Java virtual machine. This
* method never returns normally.
*
* <p> This method should be used with extreme caution. Unlike the
* <tt>{@link #exit exit}</tt> method, this method does not cause shutdown
* hooks to be started and does not run uninvoked finalizers if
* finalization-on-exit has been enabled. If the shutdown sequence has
* already been initiated then this method does not wait for any running
* shutdown hooks or finalizers to finish their work. <p>
*
* If process model exists, Runtime.halt() must rely on the process
* exiting to release resources.
* <p>
* If process model does not exist, and a security manager exists,
* the security manager by default must prohibit calls to Runtime.halt()
* by throwing SecurityException. Otherwise, the system will hang
* indefinitely when called.
* <p>
*
* @param status
* Termination status. By convention, a nonzero status code
* indicates abnormal termination. If the <tt>{@link Runtime#exit
* exit}</tt> (equivalently, <tt>{@link System#exit(int)
* System.exit}</tt>) method has already been invoked then this
* status code will override the status code passed to that method.
*
* @throws SecurityException
* If a security manager is present and its <tt>{@link
* SecurityManager#checkExit checkExit}</tt> method does not permit
* an exit with the specified status
*
* @see #exit
* @see #addShutdownHook
* @see #removeShutdownHook
* @since 1.3
*/
public void halt(int status) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkExit(status);
}
Shutdown.halt(status);
}
/**
* Enable or disable finalization on exit; doing so specifies that the
* finalizers of all objects that have finalizers that have not yet been
* automatically invoked are to be run before the Java runtime exits.
* By default, finalization on exit is disabled.
*
* <p>If there is a security manager,
* its <code>checkExit</code> method is first called
* with 0 as its argument to ensure the exit is allowed.
* This could result in a SecurityException.
*
* param value true to enable finalization on exit, false to disable
* deprecated This method is inherently unsafe. It may result in
* finalizers being called on live objects while other threads are
* concurrently manipulating those objects, resulting in erratic
* behavior or deadlock.
*
* throws SecurityException
* if a security manager exists and its <code>checkExit</code>
* method doesn't allow the exit.
*
* see java.lang.Runtime#exit(int)
* see java.lang.Runtime#gc()
* see java.lang.SecurityManager#checkExit(int)
* since JDK1.1
*
public static void runFinalizersOnExit(boolean value) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
try {
security.checkExit(0);
} catch (SecurityException e) {
throw new SecurityException("runFinalizersOnExit");
}
}
Shutdown.setRunFinalizersOnExit(value);
}
*/
/* Helper for exec
*/
private native Process execInternal(String cmdarray[], String envp[], String path)
throws IOException;
/**
* Executes the specified string command in a separate process.
* <p>
* The <code>command</code> argument is parsed into tokens and then
* executed as a command in a separate process. The token parsing is
* done by a {@link java.util.StringTokenizer} created by the call:
* <blockquote><pre>
* new StringTokenizer(command)
* </pre></blockquote>
* with no further modifications of the character categories.
* This method has exactly the same effect as
* <code>exec(command, null)</code>.
* <p>
* If process model exists, Runtime.exec() must behave as it
* does in the J2SE specification.
* <p>
* If process model does not exist, Runtime.exec() and all
* java.lang.Process methods must throw SecurityException.
* <p>
*
* @param command a specified system command.
* @return a <code>Process</code> object for managing the subprocess.
* @exception SecurityException if a security manager exists and its
* <code>checkExec</code> method doesn't allow creation of a subprocess.
* @exception IOException if an I/O error occurs
* @exception NullPointerException if <code>command</code> is
* <code>null</code>
* @exception IllegalArgumentException if <code>command</code> is empty
*
* @see java.lang.Runtime#exec(java.lang.String, java.lang.String[])
* @see java.lang.SecurityManager#checkExec(java.lang.String)
*/
public Process exec(String command) throws IOException {
return exec(command, null);
}
/**
* Executes the specified string command in a separate process with the
* specified environment.
* <p>
* This method breaks the <code>command</code> string into tokens and
* creates a new array <code>cmdarray</code> containing the tokens in the
* order that they were produced by the string tokenizer; it
* then performs the call <code>exec(cmdarray, envp)</code>. The token
* parsing is done by a {@link java.util.StringTokenizer} created by
* the call:
* <blockquote><pre>
* new StringTokenizer(command)
* </pre></blockquote>
* with no further modification of the character categories.
*
* <p>
* The environment variable settings are specified by <tt>envp</tt>.
* If <tt>envp</tt> is <tt>null</tt>, the subprocess inherits the
* environment settings of the current process.
* <p>
* If process model exists, Runtime.exec() must behave as it
* does in the J2SE specification.
* <p>
* If process model does not exist, Runtime.exec() and all
* java.lang.Process methods must throw SecurityException.
* <p>
*
* @param cmd a specified system command.
* @param envp array of strings, each element of which
* has environment variable settings in format
* <i>name</i>=<i>value</i>.
* @return a <code>Process</code> object for managing the subprocess.
* @exception SecurityException if a security manager exists and its
* <code>checkExec</code> method doesn't allow creation of a subprocess.
* @exception IOException if an I/O error occurs
* @exception NullPointerException if <code>cmd</code> is null
* @exception IllegalArgumentException if <code>cmd</code> is empty
* @see java.lang.Runtime#exec(java.lang.String[])
* @see java.lang.Runtime#exec(java.lang.String[], java.lang.String[])
* @see java.lang.SecurityManager#checkExec(java.lang.String)
*/
public Process exec(String cmd, String envp[]) throws IOException {
return exec(cmd, envp, null);
}
/**
* Executes the specified string command in a separate process with the
* specified environment and working directory.
* <p>
* This method breaks the <code>command</code> string into tokens and
* creates a new array <code>cmdarray</code> containing the tokens in the
* order that they were produced by the string tokenizer; it
* then performs the call <code>exec(cmdarray, envp)</code>. The token
* parsing is done by a {@link java.util.StringTokenizer} created by
* the call:
* <blockquote><pre>
* new StringTokenizer(command)
* </pre></blockquote>
* with no further modification of the character categories.
*
* <p>
* The environment variable settings are specified by <tt>envp</tt>.
* If <tt>envp</tt> is <tt>null</tt>, the subprocess inherits the
* environment settings of the current process.
*
* <p>
* The working directory of the new subprocess is specified by <tt>dir</tt>.
* If <tt>dir</tt> is <tt>null</tt>, the subprocess inherits the
* current working directory of the current process.
*
* <p>
* If process model exists, Runtime.exec() must behave as it
* does in the J2SE specification.
* <p>
* If process model does not exist, Runtime.exec() and all
* java.lang.Process methods must throw SecurityException.
* <p>
*
* @param command a specified system command.
* @param envp array of strings, each element of which
* has environment variable settings in format
* <i>name</i>=<i>value</i>.
* @param dir the working directory of the subprocess, or
* <tt>null</tt> if the subprocess should inherit
* the working directory of the current process.
* @return a <code>Process</code> object for managing the subprocess.
* @exception SecurityException if a security manager exists and its
* <code>checkExec</code> method doesn't allow creation of a subprocess.
* @exception IOException if an I/O error occurs
* @exception NullPointerException if <code>command</code> is
* <code>null</code>
* @exception IllegalArgumentException if <code>command</code> is empty
* @see java.lang.Runtime#exec(java.lang.String[], java.lang.String[], File)
* @see java.lang.SecurityManager#checkExec(java.lang.String)
* @since 1.3
*/
public Process exec(String command, String envp[], File dir)
throws IOException {
int count = 0;
String cmdarray[];
StringTokenizer st;
if (command.length() == 0)
throw new IllegalArgumentException("Empty command");
st = new StringTokenizer(command);
count = st.countTokens();
cmdarray = new String[count];
st = new StringTokenizer(command);
count = 0;
while (st.hasMoreTokens()) {
cmdarray[count++] = st.nextToken();
}
return exec(cmdarray, envp, dir);
}
/**
* Executes the specified command and arguments in a separate process.
* <p>
* The command specified by the tokens in <code>cmdarray</code> is
* executed as a command in a separate process. This has exactly the
* same effect as <code>exec(cmdarray, null)</code>.
* <p>
* If there is a security manager, its <code>checkExec</code>
* method is called with the first component of the array
* <code>cmdarray</code> as its argument. This may result in a security
* exception.
*
* <p>
* If process model exists, Runtime.exec() must behave as it
* does in the J2SE specification.
* <p>
* If process model does not exist, Runtime.exec() and all
* java.lang.Process methods must throw SecurityException.
* <p>
*
* @param cmdarray array containing the command to call and
* its arguments.
* @return a <code>Process</code> object for managing the subprocess.
* @exception SecurityException if a security manager exists and its
* <code>checkExec</code> method doesn't allow creation of a subprocess.
* @exception IOException if an I/O error occurs
* @exception NullPointerException if <code>cmdarray</code> is
* <code>null</code>
* @exception IndexOutOfBoundsException if <code>cmdarray</code> is an
* empty array (has length <code>0</code>).
* @see java.lang.Runtime#exec(java.lang.String[], java.lang.String[])
* @see java.lang.SecurityManager#checkExec(java.lang.String)
*/
public Process exec(String cmdarray[]) throws IOException {
return exec(cmdarray, null);
}
/**
* Executes the specified command and arguments in a separate process
* with the specified environment.
* <p>
* Given an array of strings <code>cmdarray</code>, representing the
* tokens of a command line, and an array of strings <code>envp</code>,
* representing "environment" variable settings, this method creates
* a new process in which to execute the specified command.
*
* <p>
* If <tt>envp</tt> is <tt>null</tt>, the subprocess inherits the
* environment settings of the current process.
*
* <p>
* If process model exists, Runtime.exec() must behave as it
* does in the J2SE specification.
* <p>
* If process model does not exist, Runtime.exec() and all
* java.lang.Process methods must throw SecurityException.
* <p>
*
* @param cmdarray array containing the command to call and
* its arguments.
* @param envp array of strings, each element of which
* has environment variable settings in format
* <i>name</i>=<i>value</i>.
* @return a <code>Process</code> object for managing the subprocess.
* @exception SecurityException if a security manager exists and its
* <code>checkExec</code> method doesn't allow creation of a subprocess.
* @exception IOException if an I/O error occurs
* @exception NullPointerException if <code>cmdarray</code> is
* <code>null</code>
* @exception IndexOutOfBoundsException if <code>cmdarray</code> is an
* empty array (has length <code>0</code>).
* @see java.lang.Process
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkExec(java.lang.String)
*/
public Process exec(String cmdarray[], String envp[]) throws IOException {
return exec(cmdarray, envp, null);
}
/**
* Executes the specified command and arguments in a separate process with
* the specified environment and working directory.
* <p>
* If there is a security manager, its <code>checkExec</code>
* method is called with the first component of the array
* <code>cmdarray</code> as its argument. This may result in a security
* exception.
* <p>
* Given an array of strings <code>cmdarray</code>, representing the
* tokens of a command line, and an array of strings <code>envp</code>,
* representing "environment" variable settings, this method creates
* a new process in which to execute the specified command.
*
* <p>
* If <tt>envp</tt> is <tt>null</tt>, the subprocess inherits the
* environment settings of the current process.
*
* <p>
* The working directory of the new subprocess is specified by <tt>dir</tt>.
* If <tt>dir</tt> is <tt>null</tt>, the subprocess inherits the
* current working directory of the current process.
*
*
* <p>
* If process model exists, Runtime.exec() must behave as it
* does in the J2SE specification.
* <p>
* If process model does not exist, Runtime.exec() and all
* java.lang.Process methods must throw SecurityException.
* <p>
*
* @param cmdarray array containing the command to call and
* its arguments.
* @param envp array of strings, each element of which
* has environment variable settings in format
* <i>name</i>=<i>value</i>.
* @param dir the working directory of the subprocess, or
* <tt>null</tt> if the subprocess should inherit
* the working directory of the current process.
* @return a <code>Process</code> object for managing the subprocess.
* @exception SecurityException if a security manager exists and its
* <code>checkExec</code> method doesn't allow creation of a
* subprocess.
* @exception NullPointerException if <code>cmdarray</code> is
* <code>null</code>
* @exception IndexOutOfBoundsException if <code>cmdarray</code> is an
* empty array (has length <code>0</code>).
* @exception IOException if an I/O error occurs.
* @see java.lang.Process
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkExec(java.lang.String)
* @since 1.3
*/
public Process exec(String cmdarray[], String envp[], File dir)
throws IOException {
cmdarray = (String[])cmdarray.clone();
envp = (envp != null ? (String[])envp.clone() : null);
if (cmdarray.length == 0) {
throw new IndexOutOfBoundsException();
}
for (int i = 0; i < cmdarray.length; i++) {
if (cmdarray[i] == null) {
throw new NullPointerException();
}
}
if (envp != null) {
for (int i = 0; i < envp.length; i++) {
if (envp[i] == null) {
throw new NullPointerException();
}
}
}
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkExec(cmdarray[0]);
}
String path = (dir == null ? null : dir.getPath());
return execInternal(cmdarray, envp, path);
}
/**
* Returns the number of processors available to the Java virtual machine.
*
* <p> This value may change during a particular invocation of the virtual
* machine. Applications that are sensitive to the number of available
* processors should therefore occasionally poll this property and adjust
* their resource usage appropriately. </p>
*
* @return the maximum number of processors available to the virtual
* machine; never smaller than one
*/
//public native int availableProcessors();
public int availableProcessors() {
return 1; // assume that CVM supports only one
}
/**
* Returns the amount of free memory in the Java Virtual Machine.
* Calling the
* <code>gc</code> method may result in increasing the value returned
* by <code>freeMemory.</code>
*
* @return an approximation to the total amount of memory currently
* available for future allocated objects, measured in bytes.
*/
public native long freeMemory();
/**
* Returns the total amount of memory in the Java virtual machine.
* The value returned by this method may vary over time, depending on
* the host environment.
* <p>
* Note that the amount of memory required to hold an object of any
* given type may be implementation-dependent.
*
* @return the total amount of memory currently available for current
* and future objects, measured in bytes.
*/
public native long totalMemory();
/**
* Returns the maximum amount of memory that the Java virtual machine will
* attempt to use. If there is no inherent limit then the value {@link
* java.lang.Long#MAX_VALUE} will be returned. </p>
*
* @return the maximum amount of memory that the virtual machine will
* attempt to use, measured in bytes
*/
public native long maxMemory();
/**
* Runs the garbage collector.
* Calling this method suggests that the Java virtual machine expend
* effort toward recycling unused objects in order to make the memory
* they currently occupy available for quick reuse. When control
* returns from the method call, the virtual machine has made
* its best effort to recycle all discarded objects.
* <p>
* The name <code>gc</code> stands for "garbage
* collector". The virtual machine performs this recycling
* process automatically as needed, in a separate thread, even if the
* <code>gc</code> method is not invoked explicitly.
* <p>
* The method {@link System#gc()} is the conventional and convenient
* means of invoking this method.
*/
public native void gc();
/* Wormhole for calling java.lang.ref.Finalizer.runFinalization */
private static native void runFinalization0();
/**
* Runs the finalization methods of any objects pending finalization.
* Calling this method suggests that the Java virtual machine expend
* effort toward running the <code>finalize</code> methods of objects
* that have been found to be discarded but whose <code>finalize</code>
* methods have not yet been run. When control returns from the
* method call, the virtual machine has made a best effort to
* complete all outstanding finalizations.
* <p>
* The virtual machine performs the finalization process
* automatically as needed, in a separate thread, if the
* <code>runFinalization</code> method is not invoked explicitly.
* <p>
* The method {@link System#runFinalization()} is the conventional
* and convenient means of invoking this method.
*
* @see java.lang.Object#finalize()
*/
public void runFinalization() {
runFinalization0();
}
/**
* Enables/Disables tracing of instructions.
* If the <code>boolean</code> argument is <code>true</code>, this
* method suggests that the Java virtual machine emit debugging
* information for each instruction in the virtual machine as it
* is executed. The format of this information, and the file or other
* output stream to which it is emitted, depends on the host environment.
* The virtual machine may ignore this request if it does not support
* this feature. The destination of the trace output is system
* dependent.
* <p>
* If the <code>boolean</code> argument is <code>false</code>, this
* method causes the virtual machine to stop performing the
* detailed instruction trace it is performing.
*
* @param on <code>true</code> to enable instruction tracing;
* <code>false</code> to disable this feature.
*/
public native void traceInstructions(boolean on);
/**
* Enables/Disables tracing of method calls.
* If the <code>boolean</code> argument is <code>true</code>, this
* method suggests that the Java virtual machine emit debugging
* information for each method in the virtual machine as it is
* called. The format of this information, and the file or other output
* stream to which it is emitted, depends on the host environment. The
* virtual machine may ignore this request if it does not support
* this feature.
* <p>
* Calling this method with argument false suggests that the
* virtual machine cease emitting per-call debugging information.
*
* @param on <code>true</code> to enable instruction tracing;
* <code>false</code> to disable this feature.
*/
public native void traceMethodCalls(boolean on);
/**
* Loads the specified filename as a dynamic library. The filename
* argument must be a complete path name.
* From <code>java_g</code> it will automagically insert "_g" before the
* ".so" (for example
* <code>Runtime.getRuntime().load("/home/avh/lib/libX11.so");</code>).
* <p>
* First, if there is a security manager, its <code>checkLink</code>
* method is called with the <code>filename</code> as its argument.
* This may result in a security exception.
* <p>
* This is similar to the method {@link #loadLibrary(String)}, but it
* accepts a general file name as an argument rather than just a library
* name, allowing any file of native code to be loaded.
* <p>
* The method {@link System#load(String)} is the conventional and
* convenient means of invoking this method.
*
* @param filename the file to load.
* @exception SecurityException if a security manager exists and its
* <code>checkLink</code> method doesn't allow
* loading of the specified dynamic library
* @exception UnsatisfiedLinkError if the file does not exist.
* @see java.lang.Runtime#getRuntime()
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkLink(java.lang.String)
*/
public void load(String filename) {
load0(System.getCallerClass(), filename);
}
synchronized void load0(Class fromClass, String filename) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkLink(filename);
}
if (!(new File(filename).isAbsolute())) {
throw new UnsatisfiedLinkError(
"Expecting an absolute path of the library: " + filename);
}
ClassLoader.loadLibrary(fromClass, filename, true);
}
/**
* Loads the dynamic library with the specified library name.
* A file containing native code is loaded from the local file system
* from a place where library files are conventionally obtained. The
* details of this process are implementation-dependent. The
* mapping from a library name to a specific filename is done in a
* system-specific manner.
* <p>
* First, if there is a security manager, its <code>checkLink</code>
* method is called with the <code>libname</code> as its argument.
* This may result in a security exception.
* <p>
* The method {@link System#loadLibrary(String)} is the conventional
* and convenient means of invoking this method. If native
* methods are to be used in the implementation of a class, a standard
* strategy is to put the native code in a library file (call it
* <code>LibFile</code>) and then to put a static initializer:
* <blockquote><pre>
* static { System.loadLibrary("LibFile"); }
* </pre></blockquote>
* within the class declaration. When the class is loaded and
* initialized, the necessary native code implementation for the native
* methods will then be loaded as well.
* <p>
* If this method is called more than once with the same library
* name, the second and subsequent calls are ignored.
*
* @param libname the name of the library.
* @exception SecurityException if a security manager exists and its
* <code>checkLink</code> method doesn't allow
* loading of the specified dynamic library
* @exception UnsatisfiedLinkError if the library does not exist.
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkLink(java.lang.String)
*/
public void loadLibrary(String libname) {
loadLibrary0(System.getCallerClass(), libname);
}
synchronized void loadLibrary0(Class fromClass, String libname) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkLink(libname);
}
if (libname.indexOf((int)File.separatorChar) != -1) {
throw new UnsatisfiedLinkError(
"Directory separator should not appear in library name: " + libname);
}
ClassLoader.loadLibrary(fromClass, libname, false);
}
/**
* Creates a localized version of an input stream. This method takes
* an <code>InputStream</code> and returns an <code>InputStream</code>
* equivalent to the argument in all respects except that it is
* localized: as characters in the local character set are read from
* the stream, they are automatically converted from the local
* character set to Unicode.
* <p>
* If the argument is already a localized stream, it may be returned
* as the result.
*
* @param in InputStream to localize
* @return a localized input stream
* @see java.io.InputStream
* @see java.io.BufferedReader#BufferedReader(java.io.Reader)
* @see java.io.InputStreamReader#InputStreamReader(java.io.InputStream)
* @deprecated As of JDK 1.1, the preferred way to translate a byte
* stream in the local encoding into a character stream in Unicode is via
* the <code>InputStreamReader</code> and <code>BufferedReader</code>
* classes.
*
public InputStream getLocalizedInputStream(InputStream in) {
return in;
}
*/
/**
* Creates a localized version of an output stream. This method
* takes an <code>OutputStream</code> and returns an
* <code>OutputStream</code> equivalent to the argument in all respects
* except that it is localized: as Unicode characters are written to
* the stream, they are automatically converted to the local
* character set.
* <p>
* If the argument is already a localized stream, it may be returned
* as the result.
*
* deprecated As of JDK 1.1, the preferred way to translate a
* Unicode character stream into a byte stream in the local encoding is via
* the <code>OutputStreamWriter</code>, <code>BufferedWriter</code>, and
* <code>PrintWriter</code> classes.
*
* param out OutputStream to localize
* return a localized output stream
* see java.io.OutputStream
* see java.io.BufferedWriter#BufferedWriter(java.io.Writer)
* see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream)
* see java.io.PrintWriter#PrintWriter(java.io.OutputStream)
*
public OutputStream getLocalizedOutputStream(OutputStream out) {
return out;
}
*/
}