servlet本身提供的只有request和response对象,如果要取得session对象,只能依靠request对象,因为session属于HTTP协议范畴,而且在每次发送请求的时候,服务器都会自动为客户端设置一个cookie,所以,很自然的,session中要使用cookie机制,但是cookie又只能通过request取得,所以自然session也只能通过request取得。
取得session对象:
package org.lxh.servletdemo ; import java.io.* ; import javax.servlet.* ; import javax.servlet.http.* ; public class HttpSessionDemoServlet extends HttpServlet { public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{ HttpSession ses = req.getSession() ; System.out.println("SESSION ID --> " + ses.getId()) ; ses.setAttribute("username","李兴华") ; // 设置session属性 System.out.println("username属性内容:" + ses.getAttribute("username")) ; } public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{ this.doGet(req,resp) ; } }
web.xml:
<servlet> <servlet-name>sessiondemo</servlet-name> <servlet-class> org.lxh.servletdemo.HttpSessionDemoServlet </servlet-class> </servlet> <servlet-mapping> <servlet-name>sessiondemo</servlet-name> <url-pattern>/HttpSessionDemoServlet</url-pattern> </servlet-mapping>
2. 取得application:
package org.lxh.servletdemo ; import java.io.* ; import javax.servlet.* ; import javax.servlet.http.* ; public class ServletContextDemoServlet extends HttpServlet { public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{ ServletContext app = super.getServletContext() ; System.out.println("真实路径:" + app.getRealPath("/")) ; } public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{ this.doGet(req,resp) ; } }
web.xml:
<servlet> <servlet-name>applicationdemo</servlet-name> <servlet-class> org.lxh.servletdemo.ServletContextDemoServlet </servlet-class> </servlet> <servlet-mapping> <servlet-name>applicationdemo</servlet-name> <url-pattern>/ServletContextDemoServlet</url-pattern> </servlet-mapping>
总结:
1. 通过req.getSession() 可以取得session,可以进行登录验证操作
2. 通过getServletContext()取得application