职责链模式

//被代理类接口
public interface HelloWorld {
    void sayHello();
}
//被代理类
public class HelloWorldImpl implements HelloWorld {

    @Override
    public void sayHello() {
        // TODO Auto-generated method stub
        System.out.println("Hello World");
    }

}
//拦截器接口
public interface Interceptor {
    //前置通知
    boolean before(Object proxy,Object target,Method method,Object[] args);
    //环绕通知
     void around(Object proxy,Object target,Method method,Object[] args);
    //z后置通知
    void after(Object proxy,Object target,Method method,Object[] args);
}
//拦截器实现1
public class Interceptor1 implements Interceptor{

    @Override
    public boolean before(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("[拦截器1]的before方法");
        return true;
    }

    @Override
    public void around(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("");
    }

    @Override
    public void after(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("[拦截器1]的after方法");
    }

}
//拦截器实现2
public class Interceptor2 implements Interceptor{

    @Override
    public boolean before(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("[拦截器2]的before方法");
        return true;
    }

    @Override
    public void around(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("");
    }

    @Override
    public void after(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("[拦截器2]的after方法");
    }

}
//拦截器实现3
public class Interceptor3 implements Interceptor{

    @Override
    public boolean before(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("[拦截器3]的before方法");
        return true;
    }

    @Override
    public void around(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("");
    }

    @Override
    public void after(Object proxy, Object target, Method method, Object[] args) {
        System.out.println("[拦截器3]的after方法");
    }

}
//动态代理实现类，在平常的JDK代理上，组合了拦截器对象
public class InterceptorJdkProxy implements InvocationHandler {
    
    private Object target;//真实对象
    private Interceptor interceptor;//拦截器对象
    
    
    public InterceptorJdkProxy(Object target, Interceptor interceptor) {
        this.target = target;
        this.interceptor = interceptor;
    }
    
    public static Object bind(Object target,Interceptor interceptor) {
        return Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), new InterceptorJdkProxy(target, interceptor));
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Object object = null;
        // TODO Auto-generated method stub
        if (interceptor.before(proxy, target, method, args) == true) {
            object = method.invoke(target, args);
        }else {
            interceptor.around(proxy, target, method, args);
        }
        interceptor.after(proxy, target, method, args);
        return object;
    }

}
//最后 测试类
public class Test {
    public static void main(String[] args) {
        HelloWorld proxy1 = (HelloWorld) InterceptorJdkProxy.bind(new HelloWorldImpl(), new Interceptor1());
        HelloWorld proxy2 = (HelloWorld) InterceptorJdkProxy.bind(proxy1, new Interceptor2());
        HelloWorld proxy3 = (HelloWorld) InterceptorJdkProxy.bind(proxy2, new Interceptor3());
        proxy3.sayHello();
    }
}