【DRP】Filter拦截器-应用

【用法】

1、建立配置文件：

 1 package com.bjpowernode.drp.util.filter;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.Filter;
 6 import javax.servlet.FilterChain;
 7 import javax.servlet.FilterConfig;
 8 import javax.servlet.ServletException;
 9 import javax.servlet.ServletRequest;
10 import javax.servlet.ServletResponse;
11 
12 /**
13  * 采用Filter统一处理字符集
14  * @author yin
15  *
16  */
17 public class CharsetEncodingFilter implements Filter {
18 
19     @Override
20     public void destroy() {
21 
22     }
23 
24     @Override
25     public void doFilter(ServletRequest request, ServletResponse response,
26             FilterChain chain) throws IOException, ServletException {
27         
28         //设置字符集
29         request.setCharacterEncoding("GB18030");
30         //继续执行
31         chain.doFilter(request, response);
32     }
33 
34     @Override
35     public void init(FilterConfig arg0) throws ServletException {
36     
37 
38     }
39 
40 }

2、配置web.XML配置文件

 1 <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"  
 2     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
 3     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   
 4     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  
 5     
 6 <!--     文件名和文件相对路径 -->
 7  <filter>
 8     <filter-name>CharsetEncodingFilter</filter-name>
 9     <filter-class>com.bjpowernode.drp.util.filter.CharsetEncodingFilter</filter-class>
10 </filter>
11 
12 <!-- 文件名和拦截的页面 -->
13 <filter-mapping>
14     <filter-name>CharsetEncodingFilter</filter-name>
15     <url-pattern>*.jsp</url-pattern>
16 </filter-mapping>
17     
18 </web-app>

【改进】-字符集通过读取XML文件取得

web.XML文件：

 1 <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"  
 2     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
 3     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   
 4     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  
 5     
 6 <!--     文件名和文件相对路径 -->
 7  <filter>
 8     <filter-name>CharsetEncodingFilter</filter-name>
 9     <filter-class>com.bjpowernode.drp.util.filter.CharsetEncodingFilter</filter-class>
10     <init-param>
11         <param-name>encoding</param-name>
12         <param-value>GBK</param-value>
13     </init-param>
14 </filter>
15 
16 <!-- 文件名和拦截的页面 -->
17 <filter-mapping>
18     <filter-name>CharsetEncodingFilter</filter-name>
19     <url-pattern>*.jsp</url-pattern>
20 </filter-mapping>
21     
22 </web-app>

Filter 文件

 1 package com.bjpowernode.drp.util.filter;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.Filter;
 6 import javax.servlet.FilterChain;
 7 import javax.servlet.FilterConfig;
 8 import javax.servlet.ServletException;
 9 import javax.servlet.ServletRequest;
10 import javax.servlet.ServletResponse;
11 
12 /**
13  * 采用Filter统一处理字符集
14  * @author yin
15  *
16  */
17 public class CharsetEncodingFilter implements Filter {
18 
19     private String endcoding;
20     @Override
21     public void destroy() {
22 
23     }
24 
25     @Override
26     public void doFilter(ServletRequest request, ServletResponse response,
27             FilterChain chain) throws IOException, ServletException {
28         
29         //设置字符集
30         request.setCharacterEncoding(endcoding);
31         //继续执行
32         chain.doFilter(request, response);
33     }
34 
35     //初始化方法
36     @Override
37     public void init(FilterConfig filterConfig) throws ServletException {
38          //读取web.xml文件中 字符集的值
39         this.endcoding = filterConfig.getInitParameter("encoding");
40         System.out.println(endcoding);
41 
42     }
43 
44 }

request.getParameter() 和request.getAttribute() 区别

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总结：不断提高自己的编码效率！