1.新建一個類 CndoFilter

package com.cndo.cndoFilter.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;
import javax.servlet.http.HttpServlet;

public class CndoFilter extends HttpServlet implements Filter {

 public void doFilter(ServletRequest req, ServletResponse resp,
   FilterChain fc) throws IOException, ServletException {
  req.setCharacterEncoding("utf-8");
  resp.setContentType("text/html;utf-8");
  fc.doFilter(req, resp);
 }

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

2.修改配置檔案web.xml

<filter>
   <filter-name>filter</filter-name>
   <filter-class>com.cndo.cndoFilter.filter.CndoFilter</filter-class>
  </filter>
  <filter-mapping>
   <filter-name>filter</filter-name>
   <url-pattern>/*</url-pattern>
  </filter-mapping>

3.上面的配置檔案中的url-pattern為“/*”，所以在jsp的form中任何action都會通過過濾器，如果把配置檔案中的<url-pattern>/*</url-pattern>，改為<url-pattern>*.do</url-pattern>則action為*.do時才會通過過濾器