登陸安全過濾器

package org.thj.bookstore.util;  

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;  

import javax.servlet.http.httpservletrequest;  

import javax.servlet.http.httpservletresponse;  

public class securityfilter implements filter {  

    public void destroy() {  

    }  

    public void dofilter(servletrequest req, servletresponse res,  

            filterchain chain) throws ioexception, servletexception {  

        httpservletrequest request = (httpservletrequest)req;  

        httpservletresponse response = (httpservletresponse)res;  

        if(request.getsession().getattribute("user")==null){  

            string path = request.getcontextpath();  

//沒有登陸就跳到index.jsp  

            response.sendredirect(path + "/index.jsp");  

        }  

        else{  

            chain.dofilter(request,response);  

    public void init(filterconfig arg0) throws servletexception {  

        // todo auto-generated method stub  

}  

在web.xml中注冊：   

<filter>  

        <filter-name>securityfilter</filter-name>  

        <filter-class>org.thj.bookstore.util.securityfilter</filter-class>  

    </filter>  

    <filter-mapping>  

        <url-pattern>/jsp/*</url-pattern>  

    </filter-mapping>  

<!--隻過濾jsp目錄下的是以頁面-->  

<filter-mapping>  

        <filter-name>userlogin</filter-name>  

        <url-pattern>/jsp/user/*</url-pattern>  

        <url-pattern>/jsp/ques/*</url-pattern>  

    </filter-mapping>