1.编程思想
通过filter拦截除了主页之外的所有url地址栏的请求
然后在拦截中执行判断,通过request.getSession("user")得到用户名,如果没有用户,说明没有登陆,那么通过重定向resonse.sendDirect("xxx")返回主页,如果得到了用户名,那么执行chain.doFilter()方法
2.实现步骤:
1.创建一个类,继承implements javax.servlet.Filter
然后在doFilter()方法中执行用户是否登陆的判断
如果登陆:放行
如果没有登陆: 拦截并返回首页
3.源代码如下
3.1Filter类
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <filter> <filter-name>s</filter-name> <filter-class>s051201.Filter</filter-class> </filter> <filter-mapping> <filter-name>s</filter-name> <url-pattern>/jsps/*</url-pattern> </filter-mapping> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>s051201.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/loginServlet</url-pattern> </servlet-mapping> </web-app>
3.2Web-Info下的web.xml的配置
<filter> <filter-name>s</filter-name> <filter-class>s051201.Filter</filter-class> </filter> <filter-mapping> <filter-name>s</filter-name> <url-pattern>/jsps/*</url-pattern> </filter-mapping>