(一)spring aop动态代理
//抽象类
public interface UserService {
void save(); void delete(); void update(); void find(); }
//代理类
public class UserServiceImpl implements UserService {
@Override
public void save() {
System.out.println("保存用户!");
//int i = 1/0;
}
@Override
public void delete() {
System.out.println("删除用户!");
}
@Override
public void update() {
System.out.println("更新用户!");
}
@Override
public void find() {
System.out.println("查找用户!");
}
}
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
//观光代码=>动态代理
public class UserServiceProxyFactory implements InvocationHandler {
public UserServiceProxyFactory(UserService us) {
super();
this.us = us;
}
private UserService us;
public UserService getUserServiceProxy(){
//生成动态代理
UserService usProxy = (UserService) Proxy.newProxyInstance(UserServiceProxyFactory.class.getClassLoader(),
UserServiceImpl.class.getInterfaces(),
this);
System.out.println(this);
//返回
return usProxy;
}
@Override
public Object invoke(Object arg0, Method method, Object[] arg2) throws Throwable {
System.out.println("打开事务!");
Object invoke = method.invoke(us, arg2);
System.out.println("提交事务!");
return invoke;
}
}
public class Demo {
@Test
//动态代理
public void fun1(){
UserService us = new UserServiceImpl();
UserServiceProxyFactory factory = new UserServiceProxyFactory(us);
UserService usProxy = factory.getUserServiceProxy();
usProxy.save();
//代理对象与被代理对象实现了相同的接口
//代理对象 与 被代理对象没有继承关系
System.out.println(usProxy instanceof UserServiceImpl );//false
}}
(二)cglib动态代理
public interface UserService {
void save();
void delete();
void update();
void find();
}
public class UserServiceImpl implements UserService {
@Override
public void save() {
System.out.println("保存用户!");
//int i = 1/0;
}
@Override
public void delete() {
System.out.println("删除用户!");
}
@Override
public void update() {
System.out.println("更新用户!");
}
@Override
public void find() {
System.out.println("查找用户!");
}
}
public class UserServiceProxyFactory2 implements MethodInterceptor {
public UserService getUserServiceProxy(){
Enhancer en = new Enhancer();//帮我们生成代理对象
en.setSuperclass(UserServiceImpl.class);//设置对谁进行代理
en.setCallback(this);//代理要做什么
UserService us = (UserService) en.create();//创建代理对象
return us;
}
@Override
public Object intercept(Object prxoyobj, Method method, Object[] arg, MethodProxy methodProxy) throws Throwable {
//打开事务
System.out.println("打开事务!");
//调用原有方法
Object returnValue = methodProxy.invokeSuper(prxoyobj, arg);
//提交事务
System.out.println("提交事务!");
return returnValue;
}
}
public class Demo {
@Test
//动态代理
public void fun1(){
UserService us = new UserServiceImpl();
UserServiceProxyFactory factory = new UserServiceProxyFactory(us);
UserService usProxy = factory.getUserServiceProxy();
usProxy.save();
//代理对象与被代理对象实现了相同的接口
//代理对象 与 被代理对象没有继承关系
System.out.println(usProxy instanceof UserServiceImpl );//false
}
@Test
public void fun2(){
UserServiceProxyFactory2 factory = new UserServiceProxyFactory2();
UserService usProxy = factory.getUserServiceProxy();
usProxy.save();
//判断代理对象是否属于被代理对象类型
//代理对象继承了被代理对象=>true
System.out.println(usProxy instanceof UserServiceImpl );//true
}
}
(三)jdk的动态代理详解