- 静态代理
定义接口:
package cn.sky.testProxy.service;
public interface IUserService {
String getName(int id);
int getAge(int id);
}
实现接口:
package cn.sky.testProxy.service.impl;
import cn.sky.testProxy.service.IUserService;
public class UserServiceImpl implements IUserService {
@Override
public String getName(int id) {
return "sky";
}
@Override
public int getAge(int id) {
return 99;
}
}
测试接口实现类:
@Test
public void test1(){
IUserService userService = new UserServiceImpl();
System.out.println(userService.getName(1));
System.out.println(userService.getAge(1));
}
实现接口静态代理类:
package cn.sky.testProxy.service.proxy;
import cn.sky.testProxy.service.IUserService;
public class UserServiceProxy implements IUserService {
private IUserService userService;
public UserServiceProxy(IUserService userService){
this.userService = userService;
}
@Override
public String getName(int id) {
System.out.println("getName方法前置增强处理");
return userService.getName(id);
}
@Override
public int getAge(int id) {
System.out.println("getAge方法前置增强处理");
return userService.getAge(id);
}
}
测试静态代理类:
@Test
public void test2(){
IUserService userService = new UserServiceProxy(new UserServiceImpl());
System.out.println(userService.getName(1));
System.out.println(userService.getAge(1));
}
- jdk动态代理
@Test
public void test3() throws InterruptedException {
IUserService userService = new UserServiceImpl();
ClassLoader classLoader = userService.getClass().getClassLoader();
Class<?>[] interfaces = userService.getClass().getInterfaces();
InvocationHandler invocationHandler = new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("方法前置增强");
return method.invoke(userService,args);
}
};
IUserService proxyInstance = (IUserService) Proxy.newProxyInstance(classLoader, interfaces, invocationHandler);
System.out.println("代理类的名称:"+proxyInstance.getClass().getName());
System.out.println(proxyInstance.getName(1));
System.out.println(proxyInstance.getAge(1));
Thread.sleep(999999999);
}
使用arthas反编译获取jdk动态代理产生的代理类代码:
得到代理类代码后,再简化一下(去掉异常处理以及Object方法的代理),如下:
package com.sun.proxy;
import cn.sky.testProxy.service.IUserService;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
public final class $Proxy4 extends Proxy implements IUserService {
private static Method m3;
private static Method m4;
public $Proxy4(InvocationHandler invocationHandler) {
super(invocationHandler);
}
static {
m3 = Class.forName("cn.sky.testProxy.service.IUserService").getMethod("getName", Integer.TYPE);
m4 = Class.forName("cn.sky.testProxy.service.IUserService").getMethod("getAge", Integer.TYPE);
}
public final String getName(int n) {
return (String)this.h.invoke(this, m3, new Object[]{n});
}
public final int getAge(int n) {
return (Integer)this.h.invoke(this, m4, new Object[]{n});
}
}
由此看出,动态生成的代理类,与静态代理类一样,都实现了IUserService接口,不同点是:静态代理类直接持有UserServiceImpl对象,而动态代理类则是通过InvocationHandler间接持有UserServiceImpl对象。
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