java7 与agent_Java利用Attach机制与Agent

1.首先启动一个tomcat，jps查看进程。

image.png

2.编写agent并打包。

package agent;

import java.lang.instrument.Instrumentation;

/**

* @author qishaojun

*/

public class TestAgent {

// public static void premain(String agentArgs, Instrumentation inst) {

// System.out.println("premain start ...");

// System.out.println(agentArgs);

// }

public static void agentmain(String args, Instrumentation inst) {

System.out.println("loadagent after main run.args=" + args);

Class>[] classes = inst.getAllLoadedClasses();

for (Class> cls : classes) {

System.out.println(cls.getName());

}

System.out.println("agent run completely");

}

}

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

4.0.0

sjqi.test

agent

1.0-SNAPSHOT

jar

org.apache.maven.plugins

maven-jar-plugin

2.3.1

true

agent.TestAgent

maven 配置是为了确保jar包打出来的MANIFEST.MF是这样的

Manifest-Version: 1.0

Archiver-Version: Plexus Archiver

Created-By: Apache Maven

Built-By: MC

Build-Jdk: 1.8.0_191

Agent-Class: agent.TestAgent

3.编写操纵程序

//maven引入

com.sun

tools

1.8.0

system

C:/Program Files/Java/jdk1.8.0_191/lib/tools.jar

//代码编写

package com.sprucetec.pop;

import com.sun.tools.attach.AgentInitializationException;

import com.sun.tools.attach.AgentLoadException;

import com.sun.tools.attach.AttachNotSupportedException;

import com.sun.tools.attach.VirtualMachine;

import java.io.IOException;

/**

* @author qishaojun

*/

public class TestAgent {

public static void main(String[] args) throws IOException, AttachNotSupportedException, AgentLoadException, AgentInitializationException {

VirtualMachine vm=VirtualMachine.attach("2192");

vm.loadAgent("D:/pop-space/agent/target/agent-1.0-SNAPSHOT.jar");

}

}

4.运行效果在tomcat的控制台

image.png