字符编码Filter的实现

每天写一点，慢慢进步。
虽说在Servlet里面也可以设置编码方式，但是Filter就像一个沙漏一样，你可以随时拆卸，并且可以更灵活的设置编码方式。

package com.googlefans.filter;
public class CharacterEncodingFilter implements Filter{
   private String characterEncoding;
   private boolean enable;

   public void init(FilterConfig config)throws ServletException{
       characterEncoding=config.getInitParameter("characterEncoding");
       enable="true".equalsIgnoreCase(config.getInitParameter("enable").trim());
   }
   public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain)throws ServletException,IOException{
       if(enable&&characterEncoding!=null){
          request.setCharacterEncoding(characterEncoding);
          response.setCharacterEncoding(characterEncoding);
       }
       chain.doFilter(request,response);
   }
   public void destory(){
       charcaterEncoding=null;
   }
}

要想达到随意拆卸“沙漏”和随意设置编码方式的目的，从代码就可以看出重点就在initparameter上。下面是Filter的设置，打开项目下的web.xml

<filter>
   <filter-name>characterEncodingFilter</filter-name>
   <filter-class>com.googlefans.filter.characterEncodingFilter</filter-class>
   <init-param>
      <param-name>characterEncoding</param-name>
      <param-value>UTF-8</param-value>
   </init-param>
   <init-param>
      <param-name>enable</param-name>
      <param-value>true</param-value>
   </init-param>
</filter>
<filter-mapping>
   <filter-name>characterEncodingFilter</filter-name>
   <url-pattern>/*</url-pattern>
</filter-mapping>

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