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Instrumentation入门
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‎README.md‎

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## AOP
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* [AspectJ-编译时织入和加载类时织入](src/cn/aofeng/demo/aspectj)
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* [Instrumentation入门](src/cn/aofeng/demo/java/lang/instrument)
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## 脚本语言
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* [在Java中执行JavaScript脚本](src/cn/aofeng/demo/script/ScriptRunPerformence.java)

‎src/cn/aofeng/demo/java/lang/instrument/FirstInstrumentation.java‎

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package cn.aofeng.demo.java.lang.instrument;
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import java.lang.instrument.Instrumentation;
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import org.apache.commons.lang.StringUtils;
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import cn.aofeng.demo.util.LogUtil;
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/**
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* Instrument入口类。
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*
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* @author <a href="mailto:aofengblog@163.com">聂勇</a>
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*/
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public class FirstInstrumentation {
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public static void premain(String options, Instrumentation ins) {
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if (StringUtils.isBlank(options)) {
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LogUtil.log("instrument without options");
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} else {
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LogUtil.log("instrument with options:%s", options);
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}
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ins.addTransformer(new FirstTransformer());
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}
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}

‎src/cn/aofeng/demo/java/lang/instrument/FirstTransformer.java‎

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/**
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*
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*/
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package cn.aofeng.demo.java.lang.instrument;
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import java.lang.instrument.ClassFileTransformer;
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import java.lang.instrument.IllegalClassFormatException;
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import java.security.ProtectionDomain;
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import cn.aofeng.demo.util.LogUtil;
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/**
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* 只输出问候语，不进行字节码修改的Class转换器。
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*
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* @author <a href="mailto:aofengblog@163.com">聂勇</a>
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*/
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public class FirstTransformer implements ClassFileTransformer {
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@Override
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public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
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ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
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LogUtil.log(">>> %s", className);
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return null;
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}
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}

‎src/cn/aofeng/demo/java/lang/instrument/Hello.java‎

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package cn.aofeng.demo.java.lang.instrument;
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/**
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* Instrumentation启动类。 *
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*
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* @author <a href="mailto:aofengblog@163.com">聂勇</a>
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*/
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public class Hello {
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public static void main(String[] args) {
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// nothing
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}
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}

‎src/cn/aofeng/demo/java/lang/instrument/README.md‎

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# 一、Instrumentation入门
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* [FirstTransformer.java](FirstTransformer.java) 处理字节码，由类FirstInstrumentation执行
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* [FirstInstrumentation.java](FirstInstrumentation.java) instrumentation入口类，由javaagent载入执行
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* [build.xml](build.xml) Ant脚本，负责编译、打包和运行
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在当前目录下执行命令：
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```bash
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ant
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```
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输出信息如下：
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> [java] instrument with options:"Hello, Instrumentation"
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[java] >>> java/lang/invoke/MethodHandleImpl
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[java] >>> java/lang/invoke/MethodHandleImpl$1
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[java] >>> java/lang/invoke/MethodHandleImpl$2
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[java] >>> java/util/function/Function
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[java] >>> java/lang/invoke/MethodHandleImpl$3
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[java] >>> java/lang/invoke/MethodHandleImpl$4
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[java] >>> java/lang/ClassValue
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[java] >>> java/lang/ClassValue$Entry
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[java] >>> java/lang/ClassValue$Identity
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[java] >>> java/lang/ClassValue$Version
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[java] >>> java/lang/invoke/MemberName$Factory
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[java] >>> java/lang/invoke/MethodHandleStatics
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[java] >>> java/lang/invoke/MethodHandleStatics$1
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[java] >>> sun/misc/PostVMInitHook
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[java] >>> sun/usagetracker/UsageTrackerClient
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[java] >>> java/util/concurrent/atomic/AtomicBoolean
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[java] >>> sun/usagetracker/UsageTrackerClient$1
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[java] >>> sun/usagetracker/UsageTrackerClient$4
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[java] >>> sun/usagetracker/UsageTrackerClient$3
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[java] >>> java/io/FileOutputStream$1
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[java] >>> sun/launcher/LauncherHelper
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[java] >>> cn/aofeng/demo/java/lang/instrument/Hello
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[java] >>> sun/launcher/LauncherHelper$FXHelper
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[java] >>> java/lang/Class$MethodArray
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[java] >>> java/lang/Void
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[java] >>> java/lang/Shutdown
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[java] >>> java/lang/Shutdown$Lock

‎src/cn/aofeng/demo/java/lang/instrument/build.xml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<project name="Instrumentation" default="run" basedir="../../../../../../../">
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<property name="project.src.dir" value="${basedir}/src" />
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<property name="project.lib.dir" value="${basedir}/lib" />
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<property name="project.conf.dir" value="${basedir}/conf" />
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<property name="project.target.dir" value="${basedir}/classes" />
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<property name="project.dist.dir" value="${basedir}/dist" />
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<path id="project.classpath">
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<fileset dir="${project.lib.dir}">
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<include name="*.jar" />
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</fileset>
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</path>
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<target name="prepare">
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<delete dir="${project.target.dir}" />
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<mkdir dir="${project.target.dir}"/>
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<copy todir="${project.target.dir}">
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<fileset dir="${project.conf.dir}">
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<include name="**/*.properties" />
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<include name="**/*.xml" />
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</fileset>
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</copy>
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<delete dir="${project.dist.dir}" />
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<mkdir dir="${project.dist.dir}" />
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</target>
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<target name="compileWithJavac" depends="prepare">
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<echo message="compile with javac" />
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<javac destdir="${project.target.dir}" srcdir="${project.src.dir}" source="1.8" target="1.8"
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encoding="UTF-8" debug="true" includeantruntime="false">
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<classpath refid="project.classpath" />
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</javac>
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</target>
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<target name="package" depends="compileWithJavac">
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<jar destfile="${project.dist.dir}/hello.jar">
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<fileset dir="${project.target.dir}">
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<include name="cn/aofeng/demo/java/lang/instrument/*.class" />
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</fileset>
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<manifest>
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<attribute name="Premain-Class" value="cn.aofeng.demo.java.lang.instrument.FirstInstrumentation" />
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</manifest>
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</jar>
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</target>
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<target name="run" depends="package">
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<java classname="cn.aofeng.demo.java.lang.instrument.Hello" fork="true">
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<classpath refid="project.classpath" />
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<classpath location="${project.target.dir}" />
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<jvmarg value="-javaagent:${project.dist.dir}/hello.jar=&quot;Hello, Instrumentation&quot;" />
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</java>
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</target>
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</project>

‎src/cn/aofeng/demo/util/LogUtil.java‎

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*/
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public class LogUtil {
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public static void log(String msg) {
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System.out.println(msg);
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}
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public static void log(String msg, Object... param) {
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System.out.println( String.format(msg, param) );
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log( String.format(msg, param) );
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}
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}

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