javassist實現動態代理

建立被代理類

package javaassist;

public class Hello {
    public void say() {
        System.out.println("Hello");
    }
}

建立MethodHandler

package javaassist;

import java.lang.reflect.Method;

import javassist.util.proxy.MethodHandler;

public class MethondAop implements MethodHandler {

	@Override
	public Object invoke(Object arg0, Method arg1, Method arg2, Object[] arg3)
			throws Throwable {
		System.out.println("我來自代理");
		return arg2.invoke(arg0, arg3);
	}

}

建立測試類

package javaassist;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;

import model.User;
import annotation.Column;
import annotation.Table;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.util.proxy.ProxyFactory;
import javassist.util.proxy.ProxyObject;

public class Test {
    public static void main(String[] args) throws Exception {
    	
    	
    	ProxyFactory proxyFactory=new ProxyFactory();
    	proxyFactory.setSuperclass(Hello.class);
    	Class<?> classes=proxyFactory.createClass();
    	MethondAop methondAop=new MethondAop();
    	Object ret=classes.newInstance();
    	((ProxyObject)ret).setHandler(methondAop);
    	((Hello)ret).say();
    }
}

運行結果

我來自代理
Hello

PS

ProxyFactory 的方法 public void setHandler(MethodHandler mi) ,已通過期，api給出的理由以下

Deprecated. since 3.12 use of this method is incompatible with proxy class caching. instead clients should call method ProxyObject.setHandler(MethodHandler) to set the handler for each newly created proxy instance. calling this method will automatically disable caching of classes created by the proxy factory. Sets the default invocation handler. This invocation handler is shared among all the instances of a proxy class unless another is explicitly specified.