也道责任链模式应用

2012-11-01

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

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());          }            }

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也道责任链模式应用