on the local host.
(Or, see <a href="sample/evolve/start.html">sample/evolve/start.html</a>.)
+<h3>8. sample/hotswap/*.java</h3>
+
+<p>This shows dynamic class reloading by the JPDA.
+To run, first type the following commands:
+
+<ul><pre>
+% cd sample/hotswap
+% javac *.java
+% cd logging
+% javac *.java
+% cd ..
+</pre></ul>
+
+<p>If your Java is 1.4, then type:
+
+<ul><pre>
+% java -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000 Test
+</pre></ul>
+
+<p>If you are using Java 5, then type:
+
+<ul><pre>
+% java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000 Test
+</pre></ul>
+
+<p>Note that the class path must include <code>JAVA_HOME/lib/tools.jar</code>.
+
<h2>Hints</h2>
<p>To know the version number, type this command:
<p>- version 3.1
<ul>
+ <li>javassist.tool.HotSwapper was added.
+ <li>javassist.Dump was moved to javassist.tool.Dump.
</ul>
<p>- version 3.0 in January 18, 2005
<project name="javassist" default="jar" basedir=".">
- <property name="dist-version" value="javassist-3.0"/>
+ <property name="dist-version" value="javassist-3.1"/>
<property environment="env"/>
<property name="target.jar" value="javassist.jar"/>
debug="on"
deprecation="on"
optimize="off"
- includes="sample/**">
+ includes="sample/**"
+ excludes="sample/hotswap/**">
+ <classpath refid="classpath"/>
+ </javac>
+ <javac srcdir="${basedir}/sample/hotswap"
+ destdir="${build.classes.dir}"
+ debug="on"
+ deprecation="on"
+ optimize="off"
+ includes="*">
+ <classpath refid="classpath"/>
+ </javac>
+ <mkdir dir="${build.classes.dir}/logging"/>
+ <javac srcdir="${basedir}/sample/hotswap/logging"
+ destdir="${build.classes.dir}/logging"
+ debug="on"
+ deprecation="on"
+ optimize="off"
+ includes="*">
<classpath refid="classpath"/>
</javac>
<copy file="sample/vector/Test.j"
<copy todir="${build.classes.dir}/sample/evolve">
<fileset dir="sample/evolve"/>
</copy>
- <echo>To run the sample programs, change the current directory
+ <echo>To run the sample programs without ant, change the current directory
to ${build.classes.dir}.</echo>
</target>
</java>
</target>
+ <!-- for JDK 1.4 -->
+ <target name = "sample-hotswap" depends="sample">
+ <echo>** JAVA_HOME/lib/tools.jar must be included in CLASS_PATH</echo>
+ <java fork="true" dir="${run.dir}" classname="Test">
+ <jvmarg line="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000" />
+ <classpath refid="classpath"/>
+ </java>
+ </target>
+
+ <!-- for Java 5 -->
+ <target name = "sample-hotswap5" depends="sample">
+ <echo>** JAVA_HOME/lib/tools.jar must be included in CLASS_PATH</echo>
+ <java fork="true" dir="${run.dir}" classname="Test">
+ <jvmarg line="-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000" />
+ <classpath refid="classpath"/>
+ </java>
+ </target>
</project>
--- /dev/null
+public class HelloWorld {
+ public void print() {
+ System.out.println("hello world");
+ }
+}
--- /dev/null
+import java.io.*;
+import javassist.tool.HotSwapper;
+
+public class Test {
+ public static void main(String[] args) throws Exception {
+ HotSwapper hs = new HotSwapper(8000);
+ new HelloWorld().print();
+
+ File newfile = new File("logging/HelloWorld.class");
+ byte[] bytes = new byte[(int)newfile.length()];
+ new FileInputStream(newfile).read(bytes);
+ System.out.println("** reload a logging version");
+
+ hs.reload("HelloWorld", bytes);
+ new HelloWorld().print();
+
+ newfile = new File("HelloWorld.class");
+ bytes = new byte[(int)newfile.length()];
+ new FileInputStream(newfile).read(bytes);
+ System.out.println("** reload the original version");
+
+ hs.reload("HelloWorld", bytes);
+ new HelloWorld().print();
+ }
+}
--- /dev/null
+public class HelloWorld {
+ public void print() {
+ System.out.println("** HelloWorld.print()");
+ System.out.println("hello world");
+ }
+}
+++ /dev/null
-/*
- * Javassist, a Java-bytecode translator toolkit.
- * Copyright (C) 1999-2005 Shigeru Chiba. All Rights Reserved.
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. Alternatively, the contents of this file may be used under
- * the terms of the GNU Lesser General Public License Version 2.1 or later.
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- */
-
-package javassist;
-
-import java.io.*;
-import javassist.bytecode.ClassFile;
-import javassist.bytecode.ClassFileWriter;
-
-/**
- * Dump is a tool for viewing the class definition in the given
- * class file. Unlike the JDK javap tool, Dump works even if
- * the class file is broken.
- *
- * <p>For example,
- * <ul><pre>% java javassist.Dump foo.class</pre></ul>
- *
- * <p>prints the contents of the constant pool and the list of methods
- * and fields.
- */
-public class Dump {
- private Dump() {}
-
- /**
- * Main method.
- *
- * @param args <code>args[0]</code> is the class file name.
- */
- public static void main(String[] args) throws Exception {
- if (args.length != 1) {
- System.err.println("Usage: java Dump <class file name>");
- return;
- }
-
- DataInputStream in = new DataInputStream(
- new FileInputStream(args[0]));
- ClassFile w = new ClassFile(in);
- PrintWriter out = new PrintWriter(System.out, true);
- out.println("*** constant pool ***");
- w.getConstPool().print(out);
- out.println();
- out.println("*** members ***");
- ClassFileWriter.print(w, out);
- }
-}
--- /dev/null
+/*
+ * Javassist, a Java-bytecode translator toolkit.
+ * Copyright (C) 1999-2005 Shigeru Chiba. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. Alternatively, the contents of this file may be used under
+ * the terms of the GNU Lesser General Public License Version 2.1 or later.
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ */
+
+package javassist.tool;
+
+import java.io.*;
+import javassist.bytecode.ClassFile;
+import javassist.bytecode.ClassFileWriter;
+
+/**
+ * Dump is a tool for viewing the class definition in the given
+ * class file. Unlike the JDK javap tool, Dump works even if
+ * the class file is broken.
+ *
+ * <p>For example,
+ * <ul><pre>% java javassist.tool.Dump foo.class</pre></ul>
+ *
+ * <p>prints the contents of the constant pool and the list of methods
+ * and fields.
+ */
+public class Dump {
+ private Dump() {}
+
+ /**
+ * Main method.
+ *
+ * @param args <code>args[0]</code> is the class file name.
+ */
+ public static void main(String[] args) throws Exception {
+ if (args.length != 1) {
+ System.err.println("Usage: java Dump <class file name>");
+ return;
+ }
+
+ DataInputStream in = new DataInputStream(
+ new FileInputStream(args[0]));
+ ClassFile w = new ClassFile(in);
+ PrintWriter out = new PrintWriter(System.out, true);
+ out.println("*** constant pool ***");
+ w.getConstPool().print(out);
+ out.println();
+ out.println("*** members ***");
+ ClassFileWriter.print(w, out);
+ }
+}
--- /dev/null
+/*
+ * Javassist, a Java-bytecode translator toolkit.
+ * Copyright (C) 1999-2005 Shigeru Chiba. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. Alternatively, the contents of this file may be used under
+ * the terms of the GNU Lesser General Public License Version 2.1 or later.
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ */
+
+package javassist.tool;
+
+import com.sun.jdi.*;
+import com.sun.jdi.connect.*;
+import com.sun.jdi.event.*;
+import com.sun.jdi.request.*;
+import java.io.*;
+import java.util.*;
+
+class Trigger {
+ void doSwap() {}
+}
+
+/**
+ * A utility class for dynamically reloading a class by
+ * the Java Platform Debugger Architecture (JPDA), or <it>HotSwap</code>.
+ * It works only with JDK 1.4 and later.
+ *
+ * <p><b>Note:</b> The new definition of the reloaded class must declare
+ * the same set of methods and fields as the original definition. The
+ * schema change between the original and new definitions is not allowed
+ * by the JPDA.
+ *
+ * <p>To use this class, the JVM must be launched with the following
+ * command line options:
+ *
+ * <ul>
+ * <p>For Java 1.4,<br>
+ * <pre>java -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000</pre>
+ * <p>For Java 5,<br>
+ * <pre>java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000</pre>
+ * </ul>
+ *
+ * <p>Note that 8000 is the port number used by <code>HotSwapper</code>.
+ * Any port number can be specified. Since <code>HotSwapper</code> does not
+ * launch another JVM for running a target application, this port number
+ * is used only for inter-thread communication.
+ *
+ * <p>Furthermore, <code>JAVA_HOME/lib/tools.jar</code> must be included
+ * in the class path.
+ *
+ * <p>Using <code>HotSwapper</code> is easy. See the following example:
+ *
+ * <ul><pre>
+ * CtClass clazz = ...
+ * byte[] classFile = clazz.toBytecode();
+ * HotSwapper hs = new HostSwapper(8000); // 8000 is a port number.
+ * hs.reload("Test", classFile);
+ * </pre></ul>
+ *
+ * <p><code>reload()</code>
+ * first unload the <code>Test</code> class and load a new version of
+ * the <code>Test</code> class.
+ * <code>classFile</code> is a byte array containing the new contents of
+ * the class file for the <code>Test</code> class. The developers can
+ * repatedly call <code>reload()</code> on the same <code>HotSwapper</code>
+ * object so that they can reload a number of classes.
+ *
+ * @since 3.1
+ */
+public class HotSwapper {
+ private VirtualMachine jvm;
+ private MethodEntryRequest request;
+ private Map newClassFiles;
+
+ private Trigger trigger;
+
+ private static final String HOST_NAME = "localhost";
+ private static final String TRIGGER_NAME = "javassist.tool.Trigger";
+
+ /**
+ * Connects to the JVM.
+ *
+ * @param port the port number used for the connection to the JVM.
+ */
+ public HotSwapper(int port)
+ throws IOException, IllegalConnectorArgumentsException
+ {
+ this(Integer.toString(port));
+ }
+
+ /**
+ * Connects to the JVM.
+ *
+ * @param port the port number used for the connection to the JVM.
+ */
+ public HotSwapper(String port)
+ throws IOException, IllegalConnectorArgumentsException
+ {
+ jvm = null;
+ request = null;
+ newClassFiles = null;
+ trigger = new Trigger();
+ AttachingConnector connector
+ = (AttachingConnector)findConnector("com.sun.jdi.SocketAttach");
+
+ Map arguments = connector.defaultArguments();
+ ((Connector.Argument)arguments.get("hostname")).setValue(HOST_NAME);
+ ((Connector.Argument)arguments.get("port")).setValue(port);
+ jvm = connector.attach(arguments);
+ EventRequestManager manager = jvm.eventRequestManager();
+ request = methodEntryRequests(manager, TRIGGER_NAME);
+ }
+
+ private Connector findConnector(String connector) throws IOException {
+ List connectors = Bootstrap.virtualMachineManager().allConnectors();
+ Iterator iter = connectors.iterator();
+ while (iter.hasNext()) {
+ Connector con = (Connector)iter.next();
+ if (con.name().equals(connector)) {
+ return con;
+ }
+ }
+
+ throw new IOException("Not found: " + connector);
+ }
+
+ private static MethodEntryRequest methodEntryRequests(
+ EventRequestManager manager,
+ String classpattern) {
+ MethodEntryRequest mereq = manager.createMethodEntryRequest();
+ mereq.addClassFilter(classpattern);
+ mereq.setSuspendPolicy(EventRequest.SUSPEND_EVENT_THREAD);
+ return mereq;
+ }
+
+ private void deleteEventRequest(EventRequestManager manager,
+ MethodEntryRequest request) {
+ manager.deleteEventRequest(request);
+ }
+
+ /**
+ * Reloads a class.
+ *
+ * @param className the fully-qualified class name.
+ * @param classFile the contents of the class file.
+ */
+ public void reload(String className, byte[] classFile) {
+ ReferenceType classtype = toRefType(className);
+ Map map = new HashMap();
+ map.put(classtype, classFile);
+ reload2(map, className);
+ }
+
+ /**
+ * Reloads a class.
+ *
+ * @param classFiles a map between fully-qualified class names
+ * and class files. The type of the class names
+ * is <code>String</code> and the type of the
+ * class files is <code>byte[]</code>.
+ */
+ public void reload(Map classFiles) {
+ Set set = classFiles.entrySet();
+ Iterator it = set.iterator();
+ Map map = new HashMap();
+ String className = null;
+ while (it.hasNext()) {
+ Map.Entry e = (Map.Entry)it.next();
+ className = (String)e.getKey();
+ map.put(toRefType(className), e.getValue());
+ }
+
+ if (className != null)
+ reload2(map, className + " etc.");
+ }
+
+ private ReferenceType toRefType(String className) {
+ List list = jvm.classesByName(className);
+ if (list == null || list.isEmpty())
+ throw new RuntimeException("no such a class: " + className);
+ else
+ return (ReferenceType)list.get(0);
+ }
+
+ private void reload2(Map map, String msg) {
+ synchronized (trigger) {
+ startDaemon();
+ newClassFiles = map;
+ request.enable();
+ trigger.doSwap();
+ request.disable();
+ Map ncf = newClassFiles;
+ if (ncf != null) {
+ newClassFiles = null;
+ throw new RuntimeException("failed to reload: " + msg);
+ }
+ }
+ }
+
+ private void startDaemon() {
+ new Thread() {
+ private void errorMsg(Throwable e) {
+ System.err.print("Exception in thread \"HotSwap\" ");
+ e.printStackTrace(System.err);
+ }
+
+ public void run() {
+ EventSet events = null;
+ try {
+ events = waitEvent();
+ EventIterator iter = events.eventIterator();
+ while (iter.hasNext()) {
+ Event event = iter.nextEvent();
+ if (event instanceof MethodEntryEvent) {
+ hotswap();
+ break;
+ }
+ }
+ }
+ catch (Throwable e) {
+ errorMsg(e);
+ }
+ try {
+ if (events != null)
+ events.resume();
+ }
+ catch (Throwable e) {
+ errorMsg(e);
+ }
+ }
+ }.start();
+ }
+
+ EventSet waitEvent() throws InterruptedException {
+ EventQueue queue = jvm.eventQueue();
+ return queue.remove();
+ }
+
+ void hotswap() {
+ Map map = newClassFiles;
+ jvm.redefineClasses(map);
+ newClassFiles = null;
+ }
+}
--- /dev/null
+<html>
+<body>
+Utility classes.
+
+</body>
+</html>
projects / javassist.git / commitdiff