我们在servlet页面中读取前台的数据时  经常会出现乱码问题

而自己每次都要在servlet中使用

String encoding="utf-8";
               request.setCharacterEncoding(enconding);
    response.setCharacterEncoding(enconding);


来进行编码的转换  会很麻烦

所以使用过滤器 我们可以避免这些重复的工作

web.xml配置

<filter>
  <filter-name>encodingFilter</filter-name>
  <filter-class>com.scx.filter.Filter</filter-class>
  <!-- 初始化参数 -->
  <init-param>
   <param-name>encoding</param-name>
   <param-value>utf-8</param-value>
  </init-param>
 </filter>
 <!-- filter映射关系 -->
 <filter-mapping>
  <filter-name>encodingFilter</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>


Filter

package com.scx.filter;

import java.io.IOException;


import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Filter implements javax.servlet.Filter{
  //读取过滤器配置文件
  private FilterConfig config;
  public void destroy() {
    // TODO Auto-generated method stub
    
  }

  public void doFilter(ServletRequest arg0, ServletResponse arg1,
      FilterChain chain) throws IOException, ServletException {
    // TODO Auto-generated method stub
    HttpServletRequest request=(HttpServletRequest) arg0;
    HttpServletResponse response=(HttpServletResponse) arg1;
    String encoding=config.getInitParameter("encoding");
    if(encoding==null||"".equals(encoding)){
      encoding="utf-8";
    }
    request.setCharacterEncoding(encoding);
    response.setCharacterEncoding(encoding);
    chain.doFilter(request, response);
  }

  public void init(FilterConfig arg0) throws ServletException {
    // TODO Auto-generated method stub
    config=arg0;
  }

}

这样的话  在servlet里面读取到的数据就不会出现乱码的情况了