一、字符过滤器

（1）Java class编写：

package com.struts2.project.util.filter;

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 CharacterFilter implements Filter{
 private static String character=null;

 public void destroy() {
  
 }

 public void doFilter(ServletRequest req, ServletResponse res,
   FilterChain fch) throws IOException, ServletException {
  req.setCharacterEncoding(character);
  res.setCharacterEncoding(character);
  fch.doFilter(req, res);
  
 }

 @SuppressWarnings(\"static-access\")
 public void init(FilterConfig config) throws ServletException {
  this.character=config.getInitParameter(\"character\");
  if(this.character==null){
   throw new RuntimeException(\"提示：not found parameter named character\");
  }
  
 }

}

（2）web.xml文件

<filter>
<filter-name>character</filter-name>
<filter-class>com.struts2.project.util.filter.CharacterFilter</filter-class>
<init-param>
<param-name>character</param-name><param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>character</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

（3）jsp页面字符编码：pageEncoding=\"UTF-8\";

二、session过滤器

（1）Java class编写：

public class FilterDemo implements Filter{

    public void destroy() {}

    public void doFilter(ServletRequest sreq, ServletResponse response, FilterChain filterChain)

 throws IOException, ServletException {

       HttpServletRequest request=(HttpServletRequest)sreq;

       HttpSession session = request.getSession(false);

       if(session == null) {

           //如果是session超时，在此处做处理