[Design mode] -- responsibility chain mode: chainofresponsibility

[Mode overview] ---------- by xingoo

Pattern intent

Avoid excessive coupling between request senders and recipients. A requester only needs to send a request. The request is responded to by a specific object, and does not need to be concerned. The request recipient can process it by himself, or pass it back like a chain.

Therefore, requests may be lost, or there is no definite security guarantee.

Application scenarios

1. Reduce Coupling

2. enhancing the flexibility of assigning duties

3 not guaranteed to be accepted

Mode Structure

　　HandlerDefine an interface to implement the backward transmission process

 1 abstract class Handler{ 2     protected Handler successor; 3      4     public abstract void handleRequest(); 5      6     public Handler getSuccessor() { 7         return successor; 8     } 9     10     public void setSuccesor(Handler successor) {11         this.successor = successor;12     }13     14 }

 

　　ConcretehandlerIt can be responsible for the request, or it can be passed back.

 1 class ConcreteHandler extends Handler{ 2     public void handleRequest(){ 3         if(getSuccessor() != null){ 4             System.out.println("getSuccessor !"); 5             getSuccessor().handleRequest(); 6         }else{ 7             System.out.println("handle in this! request()!"); 8         } 9     }10 }

 

All code

 1 package com.xingoo; 2 abstract class Handler{ 3     protected Handler successor; 4      5     public abstract void handleRequest(); 6      7     public Handler getSuccessor() { 8         return successor; 9     }10     11     public void setSuccesor(Handler successor) {12         this.successor = successor;13     }14     15 }16 class ConcreteHandler extends Handler{17     public void handleRequest(){18         if(getSuccessor() != null){19             System.out.println("getSuccessor !");20             getSuccessor().handleRequest();21         }else{22             System.out.println("handle in this! request()!");23         }24     }25 }26 public class Client {27     public static void main(String[] args) {28         Handler handle1,handle2,handle3;29         handle1 = new ConcreteHandler();30         handle2 = new ConcreteHandler();31         handle3 = new ConcreteHandler();32         handle1.setSuccesor(handle2);33         handle2.setSuccesor(handle3);34         handle1.handleRequest();35     }36 }

View code

Running result

getSuccessor !getSuccessor !handle in this! request()!

 

[Design mode] -- responsibility chain mode: chainofresponsibility