也说责任链模式应用

背景：刚看到一个同事用了一堆ifelse嵌套来判断是否执行最后业务逻辑，感觉很纠结，就想到能不能用责任链模式来处理这类问题。顺便记录下来备后面回顾思考
问题类似如下：
Java代码 收藏代码

    if() {  
      if() {  
        if() {  
         ....  
           doBusiness();  
        }  
      }  
    }  

于是想到了责任链，直接贴代码如下：

处理接口，对外请求处理接口

    package com.shuidexiongdi.chain;  

    public interface Handler {  

        /** 
         * 执行请求 
         * @return 一般的责任链不要求一定返回boolean，这是针对具体的例子设计的责任链模式 
         */  
        public boolean doRequest();  

        public void setNextHandler(Handler handler);  

    }  

抽象一个模板类

    package com.shuidexiongdi.chain;  

    import org.apache.log4j.Logger;  


    public abstract class AbstractHandler implements Handler {  

        private static final Logger logger = Logger.getLogger(AbstractHandler.class);  

        Handler nextHandler;  

        public boolean doRequest() {  
            logger.info(this.getClass().getName() + "start..");  
            boolean flag = this.mydo();  
            logger.info(this.getClass().getName() + "flag: " + flag);  
            //如果当前逻辑正确并且需要下一个校验，则继续，否则返回当前校验  
            if(flag && this.getNextHandler() != null) {  
                return this.getNextHandler().doRequest();  
            }  
            return flag;  
        }  

        public Handler getNextHandler() {  
            return this.nextHandler;  
        }  

        public void setNextHandler(Handler handler) {  
            this.nextHandler = handler;  
        }  

        /** 
         * 用于校验某个逻辑是否正确 
         * @return 
         */  
        public abstract boolean mydo();  

    }  

    package com.shuidexiongdi.chain;  

    public class OneHandler extends AbstractHandler implements Handler {  

        /** 
         * 用于校验某个逻辑是否正确 
         * @return 
         */  
        public boolean mydo() {  
            return true;  
        }  

    }  

    package com.shuidexiongdi.chain;  

    public class TwoHandler extends AbstractHandler implements Handler {  

        /** 
         * 用于校验某个逻辑是否正确 
         * @return 
         */  
        public boolean mydo() {  
            return true;  
        }  

    }  

    package com.shuidexiongdi.chain;  

    public class ThirdHandler extends AbstractHandler implements Handler {  

        /** 
         * 用于校验某个逻辑是否正确 
         * @return 
         */  
        public boolean mydo() {  
            return true;  
        }  

    }  

    package com.shuidexiongdi.chain;  

    /** 
     * 加入某个校验返回出错的逻辑 
     * @author dengjianquan-ghq 
     * 
     */  
    public class WrongHandler extends AbstractHandler implements Handler {  

        /** 
         * 用于校验某个逻辑是否正确 
         * @return 
         */  
        public boolean mydo() {  
            return false;  
        }  

    }  

客户端：

    package com.shuidexiongdi.chain;  

    public class Client {  

        public static void main(String[] args) {  
            doTest1();  
            doTest2();  
            doTest3();  
            doTest4();  
        }  

        private static void doTest1() {  
            Handler handler = new OneHandler();  
            Handler handler2 = new TwoHandler();  
            Handler handler3 = new ThirdHandler();  
            Handler wrongHandler = new WrongHandler();  
            handler.setNextHandler(handler2);  
            handler2.setNextHandler(handler3);  
            handler3.setNextHandler(wrongHandler);  
            System.out.println(handler.doRequest());  
        }  

        private static void doTest2() {  
            Handler handler = new OneHandler();  
            Handler handler2 = new TwoHandler();  
            Handler handler3 = new ThirdHandler();  
            handler.setNextHandler(handler2);  
            handler2.setNextHandler(handler3);  
            System.out.println(handler.doRequest());  
        }  

        private static void doTest3() {  
            Handler handler = new OneHandler();  
            Handler handler2 = new TwoHandler();  
            Handler handler3 = new ThirdHandler();  
            handler.setNextHandler(handler2);  
            handler2.setNextHandler(handler3);  
            handler3.setNextHandler(null);  
            System.out.println(handler.doRequest());  
        }  

        private static void doTest4() {  
            Handler handler = new OneHandler();  
            Handler handler2 = new TwoHandler();  
            Handler handler3 = new ThirdHandler();  
            Handler wrongHandler = new WrongHandler();  
            handler.setNextHandler(handler2);  
            handler2.setNextHandler(wrongHandler);  
            wrongHandler.setNextHandler(handler3);  
            System.out.println(handler.doRequest());  
        }  

    }