StartSystemListener
package k.filter; import javax.servlet.ServletContext; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; public class StartSystemListener implements ServletContextListener { @Override public void contextInitialized(ServletContextEvent sce) { //1.将项目上下文路径(request.getContextPath())放置到application域中. ServletContext application = sce.getServletContext(); application.setAttribute("APP_PATH", application.getContextPath()); System.err.println("=============Servlet容器创建成功 APP_PATH 被放到ServletContext作用域============= " + application.getContextPath()); } @Override public void contextDestroyed(ServletContextEvent sce) { } }
web.xml
<listener> <display-name>StartSystemListener</display-name> <listener-class>k.filter.StartSystemListener</listener-class> </listener>
login.jsp
<h1>登录页面</h1> <form action="${APP_PATH}/login.do" method="post"> 账号:<input type="text" name="userName" value="11哈哈"> <br> 密码: <input type="password" name="password" value="1"> <br> <input type="submit" value="submit"> <br> </form>