proxy.png

uml.png

客戶端與接口交互
proxy與具體類都需事先接口
proxy用于額外實現(xiàn)織入的內(nèi)容

例子

接口類

public interface Subject {
    void request();
    void hello();
}

真正實現(xiàn)類

public class RealSubject implements Subject{
    @Override
    public void request() {
        System.out.println("real subject execute request");
    }

    @Override
    public void hello() {
        System.out.println("hello");
    }
}

代理類

public class Proxy implements Subject{

// 代理類中引用實際實現(xiàn)類
    private RealSubject realSubject;

    public Proxy(RealSubject realSubject) {
        this.realSubject = realSubject;
    }

// 在實際對象執(zhí)行相應(yīng)邏輯的前后通過代理對象添加額外的邏輯功能
    @Override
    public void request() {
        System.out.println("before");
        try{
            realSubject.request();
        }catch (Exception e){
            System.out.println("ex:"+e.getMessage());
            throw e;
        }finally {
            System.out.println("after");
        }
    }

    @Override
    public void hello() {
        realSubject.hello();
    }
}

客戶端

public class Client {

    public static void main(String[] args){
        Subject subject = new Proxy(new RealSubject());
        subject.request();
    }
}