EncodingFilter.java的书写 :

package org.whc;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class EncodingFilter implements Filter {

protected String encoding = null;
protected FilterConfig config;

public void init(FilterConfig filterConfig) throws ServletException{//初始化操作
    this.config = filterConfig;   
    //得到在web.xml中配置的编码
    this.encoding = filterConfig.getInitParameter("Encoding");//读取配置文件中的编码方式
   }
   public void doFilter(
     ServletRequest request,
     ServletResponse response,
     FilterChain chain)
     throws IOException,ServletException{
     if(request.getCharacterEncoding() == null){//如果页面的没有编码方式,我们使用过滤器来加载
     //得到指定的编码
     String encode = getEncoding();
     if(encode != null){
      //设置request的编码
      request.setCharacterEncoding(encode);
      response.setCharacterEncoding(encode);
    }
   }
   chain.doFilter(request,response);
}
protected String getEncoding(){
    return encoding;
}
public void destroy(){
}
}

配置XML:

<filter>
<filter-name>EncodingFilter</filter-name>
<filter-class>code.EncodingFilter</filter-class>
    <init-param>
   <param-name>Encoding</param-name>
   <param-value>GB2312</param-value>
</init-param>
</filter>

<!-- EncodingFilter mapping -->
<filter-mapping>
<filter-name>EncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>