过滤器应用

package com.yal.character.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; ­

/** ­

* @author 张少年

* @date 2008-3-20 ­

* 解决Struts中文显示乱码问题 ­

* */ ­

public class SetCharacterEncodingFilter implements Filter { ­

protected String encoding = null; ­

protected FilterConfig filterConfig = null; ­

protected boolean ignore = true; //在web.xml文件里定义filter时要用到此参数 ­

public void destroy() { ­

// TODO Auto-generated method stub ­

this.encoding = null; ­

this.filterConfig = null; ­

} ­

public void doFilter(ServletRequest request, ServletResponse response, ­

FilterChain chain) throws IOException, ServletException { ­

// TODO Auto-generated method stub ­

// Conditionally select and set the character encoding to be used ­

if (ignore || (request.getCharacterEncoding() == null)) { ­

String encoding = selectEncoding(request); ­

if (encoding != null) ­

request.setCharacterEncoding(encoding); ­

} ­

//Pass control on to the next filter ­

chain.doFilter(request, response); ­

} ­

public void init(FilterConfig filterConfig) throws ServletException { ­

// TODO Auto-generated method stub ­

this.filterConfig = filterConfig; ­

this.encoding = filterConfig.getInitParameter("encoding"); ­

String value = filterConfig.getInitParameter("ignore"); ­

if (value == null) ­

this.ignore = true; ­

else if (value.equalsIgnoreCase("true")) ­

this.ignore = true; ­

else if (value.equalsIgnoreCase("yes")) ­

this.ignore = true; ­

else ­

this.ignore = false; ­

} ­

protected String selectEncoding(ServletRequest request) { ­

return (this.encoding); ­

} ­

} ­

//class end ­

(注：假如我们是用tomcat作服务器的话，那就更方便了，我们可以直接在tomcat的webapps\jsp-examples\Web-INF\classes\filters目录中的两个源文件RequestDumperFilter.java，SetCharacterEncodingFilter.java复制到你使用的包下。) ­

2.写好这个类以后，我们就在WEB应用的web.xml文件里定义Filter类，完整web.xml文件如下： ­

<?xml version="1.0" encoding="UTF-8"?> ­

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> ­

<web-app> ­

<!-- 定义Filter，解决struts中文问题 --> ­

<filter> ­

<filter-name>Set Character Encoding</filter-name> ­

<filter-class>com.yal.character.Filter.SetCharacterEncodingFilter</filter-class>//包名 ­

<init-param> ­

<!-- 定义编码格式，我用的是GBK --> ­

<param-name>encoding</param-name> ­

<param-value>GBK</param-value> ­

</init-param> ­

<init-param> ­

<!-- innore参数是在过滤器类定义的 --> ­

<param-name>ignore</param-name> ­

<param-value>true</param-value> ­

</init-param> ­

</filter> ­

<filter-mapping> ­

<filter-name>Set Character Encoding</filter-name> ­

<servlet-name>action</servlet-name> ­

</filter-mapping> ­

<filter-mapping> ­

<filter-name>Set Character Encoding</filter-name> ­

<servlet-name>*.jsp</servlet-name> ­

</filter-mapping> ­

<!-- Filter 定义结束 --> ­

<servlet> ­

<servlet-name>action</servlet-name> ­

<servlet-class>org.apache.struts.action.ActionServlet</servlet-class> ­

<init-param> ­

<param-name>config</param-name> ­

<param-value>/WEB-INF/struts-config.xml</param-value> ­

</init-param> ­

<init-param> ­

<param-name>debug</param-name> ­

<param-value>3</param-value> ­

</init-param> ­

<init-param> ­

<param-name>detail</param-name> ­

<param-value>3</param-value> ­

</init-param> ­

<load-on-startup>0</load-on-startup> ­

</servlet> ­

<servlet-mapping> ­

<servlet-name>action</servlet-name> ­

<url-pattern>*.do</url-pattern> ­

</servlet-mapping> ­

<welcome-file-list> ­

<welcome-file>index.jsp</welcome-file> ­

</welcome-file-list> ­

<taglib> ­

<taglib-uri>/WEB-INF/jesun.tld</taglib-uri> ­

<taglib-location>/WEB-INF/jesun.tld</taglib-location> ­

</taglib> ­

</web-app> ­

(3)以后编写JSP文件时，记得加入下面两句： ­

<%@page contentType="text/html;charset=GBK"%> ­

<META http-equiv=Content-Type content="text/html;charset=GBK"> ­

到这里我们的工作就做完了，在程序里我们不需要再作任何其它处理，呵呵­