filter用户验证

Question

import java.io.IOException;
import java.io.PrintWriter;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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Testfilter extends HttpServlet implements Filter { private FilterConfig config;
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {

在这里写你需要验证的东西比如session里有没有这个用户
                        
arg2.doFilter(arg0, arg1);

// TODO Auto-generated method stub } public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
this.config = arg0;
} /**
 * Constructor of the object.
 */
public Testfilter() {
super();
} /**
 * Destruction of the servlet. <br>
 */
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}}
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" 
xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>test</servlet-name>
    <servlet-class>test</servlet-class>
  </servlet>
   <filter>
<filter-name>Testfilter</filter-name>
<filter-class>Testfilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Testfilter</filter-name>
<servlet-name>test</servlet-name>
</filter-mapping>  <servlet-mapping>
    <servlet-name>test</servlet-name>
    <url-pattern>/servlet/test</url-pattern>
  </servlet-mapping>
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>