JSP编码过滤器的配置和使用

2017-06-17     浏览次数:

一、写一个过滤器类
package com.test.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 CharacterEncodingFilter implements Filter {  
   
     protected FilterConfig filterConfig = null;       
     protected String encoding = "";  
   
     public void destroy() {  
         filterConfig = null;  
         encoding = null;  
     }  
   
     public void doFilter(ServletRequest request, ServletResponse response,  
             FilterChain filterChain) throws IOException, ServletException {  
         if (encoding != null) { 
        	 //设置request和response的编程格式,注意两个都要设,若没设response的
             //charset,则在输出页面会显示乱码。
             request.setCharacterEncoding(this.encoding); 
             response.setContentType("text/html;charset=utf-8");
         }  
         //继续执行下一个过滤器
         filterChain.doFilter(request, response);  
     }  
   
     public void init(FilterConfig filterConfig) throws ServletException {  
         this.filterConfig = filterConfig;  
        this.encoding = filterConfig.getInitParameter("encoding");  
        
     }  
 } 

二、在web.xml中配置该过滤器的使用,加入下面配置代码:
 <filter>  
    <filter-name>CharacterEncodingFilter</filter-name>  
    <filter-class>com.test.filter.CharacterEncodingFilter</filter-class>    
       <init-param>  
         <param-name>encoding</param-name>  
         <param-value>utf-8</param-value>  
     </init-param>  
   </filter>  
  <filter-mapping>     
     <filter-name>CharacterEncodingFilter</filter-name>  
     <url-pattern>/*</url-pattern>  
   </filter-mapping> 

三、写JSP和Servlet进行测试
JSP:
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
        <!-- 设置网页不缓存 -->
	<META HTTP-EQUIV="pragma" CONTENT="no-cache"> 
	<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache, must-revalidate"> 
	<META HTTP-EQUIV="expires" CONTENT="Wed, 26 Feb 1997 08:21:57 GMT">
    <title>filterTest</title>

  </head>
  <body>
    <form action="servlet/LoginServlet" method="post" >
    username:<input type="text" id="username" name="username"/><br>
    password:<input type="password" id="password" name="password"/><br>
    <input type="button" value="提交" onclick="this.form.submit()" />
    </form>

  </body>
</html>


Servlet:
package com.test.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


public class LoginServlet extends HttpServlet {

	
	public LoginServlet() {
		super();
	}

	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}
	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
//页面转发,留意这里并没有对request和response的编码格式进行设置,如果没有
//编码过滤器,则会在跳到的页面中无法显示中文
		this.getServletContext().getRequestDispatcher("/resultLogin.jsp").forward(request, response);
		
	}
	public void init() throws ServletException {
		// Put your code here
	}
}


输出页面JSP:
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

  <head>  
    <title>My JSP 'resultLogin.jsp' starting page</title>
  </head>
    <body>
 	username::<%=request.getParameter("username") %><br>
 	password::<%=request.getParameter("password") %>
  </body>
</html>

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