Filter編碼過濾器

在WEB應用開發中，其中編碼問題一直爲開發者頭疼。在JAVA WEB開發中，我們可以編寫過濾器（filter）解決編碼問題，而不用在每個JSP/SERLVET中使用request.setCharacterCoding()設置編碼。

如下編寫的過濾器代碼：

WEB.XML

1. <?xml version="1.0" encoding="UTF-8"?>
2. <web-app version="2.4" 
3.     xmlns="http://java.sun.com/xml/ns/j2ee" 
4.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
5.     xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
6.     http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
7.     <filter>
8.         <filter-name>charsetCodingFilter</filter-name>
9.         <filter-class>CharsetCodingFilter</filter-class>
10.         <init-param>
11.             <param-name>charset</param-name>
12.             <param-value>gbk</param-value>
13.         </init-param>       
14.     </filter>
15.     <filter-mapping>
16.         <filter-name>charsetCodingFilter</filter-name>
17.         <url-pattern>/*</url-pattern>
18.     </filter-mapping>
19. </web-app>

CharsetCodingFilter.java

1. import java.io.IOException;
3. import javax.servlet.Filter;
4. import javax.servlet.FilterChain;
5. import javax.servlet.FilterConfig;
6. import javax.servlet.ServletException;
7. import javax.servlet.ServletRequest;
8. import javax.servlet.ServletResponse;
11. public class CharsetCodingFilter implements Filter {
12.     private String charset;
14.     public void destroy() {
15.         // TODO Auto-generated method stub
17.     }
19.     public void doFilter(ServletRequest req, ServletResponse resp,
20.             FilterChain chain) throws IOException, ServletException {
21.         // TODO Auto-generated method stub
22.         req.setCharacterEncoding(charset);
23.         chain.doFilter(req, resp);
25.     }
27.     public void init(FilterConfig config) throws ServletException {
28.         // TODO Auto-generated method stub
29.         this.charset=config.getInitParameter("charset");
30.     }
32. }