动态代理

基于jdk的动态代理和基于cglib的动态代理实现方式。

基于jdk的动态代理(有接口)

//接口
public interface User {
    void save();
}

//被代理类
class UserImpl implements User{
    public void save(){
        System.out.println("save running......");
    }
}

//增强方法
class UserAdvice{
    public void before(){
        System.out.println("before save");
    }

    public void after(){
        System.out.println("after save");
    }
}

//代理工厂类
class ProxyFactory{
    public static Object getProxy(){
        MyInvocationHandler handler = new MyInvocationHandler();
        //被代理对象
        User user = new UserImpl();
        //增强对象
        UserAdvice userAdvice = new UserAdvice();
        handler.setAdvice(userAdvice);
        handler.setObj(user);
        //返回代理对象
        return Proxy.newProxyInstance(user.getClass().getClassLoader(),
                                      user.getClass().getInterfaces(),handler);
    }
}

class MyInvocationHandler implements InvocationHandler{
    //被代理对象
    private Object obj;
    public void setObj(Object obj){
        this.obj = obj;
    }
    //增强对象
    private UserAdvice advice;
    public void setAdvice(UserAdvice advice){
        this.advice = advice;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) 
        throws Throwable {
        advice.before();
        Object invoke = method.invoke(obj, args);
        advice.after();
        return invoke;
    }
}

//测试
class Test{
    public static void main(String[] args) {
        User proxy = (User) ProxyFactory.getProxy();
        proxy.save();
    }
}

基于cglib的动态代理(无接口)

//被代理对象
public class Target {

    public void save(){
        System.out.println("save running......");
    }
}
//增强
class Advice{
    public void before(){
        System.out.println("save before");
    }

    public void after(){
        System.out.println("save after");
    }
}

class Test{
    public static void main(String[] args) {
        Target target = new Target();
        Advice advice = new Advice();
        //创建增强器
        Enhancer enhancer = new Enhancer();
        //设置父类(被代理类)
        enhancer.setSuperclass(Target.class);
        //设置回调
        enhancer.setCallback(new MethodInterceptor() {
            @Override
            public Object intercept(Object o, Method method, Object[] objects,
                                    MethodProxy methodProxy) throws Throwable {
                //执行前置
                advice.before();
                //执行目标
                Object invoke = method.invoke(target, args);
                //执行后置
                advice.after();
                return invoke;
            }
        });
        //创建代理对象
        Target proxy = (Target) enhancer.create();
        proxy.save();
    }
}