https://docs.oracle.com/javase/8/docs/jdk/api/attach/spec/com/sun/tools/attach/VirtualMachine.html


static VirtualMachine	attach(String id)
Attaches to a Java virtual machine.


static VirtualMachine	attach(VirtualMachineDescriptor vmd)
Attaches to a Java virtual machine.

abstract void	detach()
Detach from the virtual machine.

abstract Properties	getAgentProperties()
Returns the current agent properties in the target virtual machine.


abstract Properties	getSystemProperties()
Returns the current system properties in the target virtual machine.

static List	list()
Return a list of Java virtual machines.


void	loadAgent(String agent)
Loads an agent.
在运行时动态加载  java agent



abstract void	loadAgent(String agent, String options)
Loads an agent.

void	loadAgentLibrary(String agentLibrary)
Loads an agent library.

abstract void	loadAgentLibrary(String agentLibrary, String options)
Loads an agent library.

void	loadAgentPath(String agentPath)
Load a native agent library by full pathname.

abstract void	loadAgentPath(String agentPath, String options)
Load a native agent library by full pathname.


attach DIY

ShowClassAgent
MyAttachTest

Agent-Class dyyx.agent.attach.ShowClassAgent

mvn install -f pom-attach-agent.xml 

java -cp .:jvmtools-1.0.jar dyyx.agent.attach.MyAttachTest 60295 jvmtools-1.0.jar

Caused by: java.lang.ClassNotFoundException: com.sun.tools.attach.VirtualMachine

java -cp .:jvmtools-1.0.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_121.jdk/Contents/Home/lib/tools.jar dyyx.agent.attach.MyAttachTest 60295 jvmtools-1.0.jar
Exception in thread "main" com.sun.tools.attach.AgentLoadException: Agent JAR not found or no Agent-Class attribute


java -cp .:jvmtools-1.0.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_121.jdk/Contents/Home/lib/tools.jar dyyx.agent.attach.MyAttachTest 60295 /Users/dugang/work/demos/jvmtools/target/jvmtools-1.0.jar
agent jar 使用 全路径

目标JVM进程 (PID 60295) 控制台输出 加载的类名

完整代码
https://gitee.com/dyyx/demos/tree/master/jvmtools/src/main/java/dyyx/agent/attach



 java代码获取所有jvm进程 
 jvm外挂工具揭秘 
 javaagent机制 
 java debug 原理简介 
 javaagent两种加载方式及实例