This shows dynamic class reloading by the JPDA. +To run, first type the following commands: + +
+% cd sample/hotswap +% javac *.java +% cd logging +% javac *.java +% cd .. ++ +
If your Java is 1.4, then type: + +
+% java -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000 Test ++ +
If you are using Java 5, then type: + +
+% java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000 Test ++ +
Note that the class path must include JAVA_HOME/lib/tools.jar.
+
To know the version number, type this command: @@ -258,6 +285,8 @@
- version 3.1
- version 3.0 in January 18, 2005
diff --git a/build.xml b/build.xml
index 712c7827..3c3e3bdc 100644
--- a/build.xml
+++ b/build.xml
@@ -6,7 +6,7 @@
For example, - *
% java javassist.Dump foo.class+ *
% java javassist.tool.Dump foo.class* *
prints the contents of the constant pool and the list of methods
* and fields.
diff --git a/src/main/javassist/tool/HotSwapper.java b/src/main/javassist/tool/HotSwapper.java
new file mode 100644
index 00000000..4df6ccae
--- /dev/null
+++ b/src/main/javassist/tool/HotSwapper.java
@@ -0,0 +1,250 @@
+/*
+ * 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 Note: 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.
+ *
+ * To use this class, the JVM must be launched with the following
+ * command line options:
+ *
+ * For Java 1.4, For Java 5, Note that 8000 is the port number used by Furthermore, Using
+ *
+ * java -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000
+ *
+ * java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000
+ *
+ *
+ * HotSwapper.
+ * Any port number can be specified. Since HotSwapper does not
+ * launch another JVM for running a target application, this port number
+ * is used only for inter-thread communication.
+ *
+ * JAVA_HOME/lib/tools.jar must be included
+ * in the class path.
+ *
+ * HotSwapper is easy. See the following example:
+ *
+ *
+ * CtClass clazz = ...
+ * byte[] classFile = clazz.toBytecode();
+ * HotSwapper hs = new HostSwapper(8000); // 8000 is a port number.
+ * hs.reload("Test", classFile);
+ *
+ *
+ * reload()
+ * first unload the Test class and load a new version of
+ * the Test class.
+ * classFile is a byte array containing the new contents of
+ * the class file for the Test class. The developers can
+ * repatedly call reload() on the same HotSwapper
+ * 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 String and the type of the
+ * class files is byte[].
+ */
+ 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;
+ }
+}
diff --git a/src/main/javassist/tool/package.html b/src/main/javassist/tool/package.html
new file mode 100644
index 00000000..1566e121
--- /dev/null
+++ b/src/main/javassist/tool/package.html
@@ -0,0 +1,6 @@
+
+