责任链模式(ChainOfResponsibiliby、Filter)

Request 类:

 1 package com.demo; 2  3 public class Request { 4    5   private String requestStr; 6  7   public String getRequestStr() { 8     return requestStr; 9   }10 11   public void setRequestStr(String requestStr) {12     this.requestStr = requestStr;13   }14 15 }

Response 类:

 1 package com.demo; 2  3 public class Response { 4    5   private String responseStr; 6  7   public String getResponseStr() { 8     return responseStr; 9   }10 11   public void setResponseStr(String responseStr) {12     this.responseStr = responseStr;13   }14   15 }

Filter 接口:

1 package com.demo;2 3 public interface Filter {4   void doFilter(Request request,Response response,FilterChain chain);5 }

FilterChain 类，实现Filter接口，重写doFilter()方法，用来遍历过滤器链中所有的filter:

 1 package com.demo; 2  3 import java.util.ArrayList; 4  5 public class FilterChain implements Filter{ 6    7   //过滤器链 8   private ArrayList<Filter> chain = new ArrayList<Filter>(); 9   10   //过滤器链的索引11   int index = 0;12   13   //往过滤器链中添加过滤器14   public ArrayList<Filter> add(Filter filter){15     chain.add(filter);16     return chain;17   }18   19   /**20    * 重写 doFilter方法21    * 如果没有遍历完，调用特定过滤器的doFilter方法22   */23   @Override24   public void doFilter(Request request, Response response, FilterChain chain) {25     //如果遍历完过滤器链，则返回26     if(index == this.chain.size()) return;27     28     Filter filter = this.chain.get(index);29     index ++;30     filter.doFilter(request, response, chain);31   }32   33 }

HTMLFilter (Fiter接口的实现类):

 1 package com.demo; 2  3 public class HTMLFilter implements Filter { 4  5   @Override 6   public void doFilter(Request request, Response response, FilterChain chain) { 7     //处理过滤器该干的事情 8     request.setRequestStr(request.getRequestStr().replace('<', '[').replace('>', ']') 9         + "---HTMLFilter()");10     11     //跳往下一个过滤器12     chain.doFilter(request, response, chain);13     14     //回调15     response.setResponseStr(response.getResponseStr() + "---HTMLFilter()");16   }17 18 }

SensitiveFilter (Fiter接口的实现类):

 1 package com.demo; 2  3 public class SensitiveFilter implements Filter { 4  5   @Override 6   public void doFilter(Request request, Response response, FilterChain chain) { 7     //处理过滤器该干的事情 8     request.setRequestStr(request.getRequestStr().replace("被就业", "就业").replace("敏感", "")  9         + "---SensitiveFilter()");10     11     //跳往下一个过滤器12     chain.doFilter(request, response, chain);13     14     //回调15     response.setResponseStr(response.getResponseStr() + "---SensitiveFilter()");16   }17 18 }

Main 执行过滤器操作的类:

 1 package com.demo; 2  3 public class Main { 4   public static void main(String[] args) { 5     //请求信息 6     String msg = "大家好:)，<script>，敏感，被就业，网络授课没感觉，因为看不见大家伙儿"; 7      8     //实例化Request对象 9     Request request = new Request();10     request.setRequestStr(msg);11     12     //实例化Response对象13     Response response = new Response();14     response.setResponseStr("response");15     16     //过滤器链17     FilterChain chain = new FilterChain();18     chain.add(new HTMLFilter()).add(new SensitiveFilter());19     20     //开始过滤21     chain.doFilter(request, response, chain);22     23     //打印处理结果24     System.out.println(request.getRequestStr());25     System.out.println(response.getResponseStr());26     27   }28 }

思路：

　　在操作类中调用过滤器链的doFilter方法后，开始遍历过滤器;

　　当每执行完该过滤器的操作后马上chain.doFilter()方法跳往下一个filter，

　　当然，下一个filter的操作思路也是一致的，直至所有的request做完后，过滤器链返回；

　　所有的filter 接着执行doFiter之后的response操作了，而且是逆序的。这样就实现了过滤器的顺着进来，逆着出去的操作。

　　如果不是很清楚，用debug模式进行调试，从main方法的doFilter开始。

代码：http://pan.baidu.com/s/1kUGVy2F 提取码：9q6z

原标题：责任链模式(ChainOfResponsibiliby、Filter)

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