Servlet笔记10--Session

Web编程中的Session：

　　代码示例：

 package com.bjpowernode.javaweb.servlet;

 import java.io.IOException;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;

 public class AccessMySelfSessionServlet extends HttpServlet {

     private static final long serialVersionUID = 1L;

     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

         String ip = request.getRemoteAddr();
         HttpSession session = request.getSession();
         System.out.println(ip + "'s session = " + session);
         //向session范围中存储数据
         session.setAttribute("username", "zhangsan");
     }
 }

 package com.bjpowernode.javaweb.servlet;

 import java.io.IOException;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;

 public class GetDataFromSessionServlet extends HttpServlet {

     private static final long serialVersionUID = 1L;

     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         HttpSession session = request.getSession();
         //从session范围中读取数据
         Object username = session.getAttribute("username");
         System.out.println(username);
     }

 }

 package com.bjpowernode.javaweb.servlet;

 import java.io.IOException;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;

 public class LogoutServlet extends HttpServlet {

     private static final long serialVersionUID = 1L;

     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

         //获取session对象，若没有获取到session对象，则新建session对象
 //        HttpSession session = request.getSession();

         //获取session对象，若没有获取到session对象，则新建session对象
 //        HttpSession session = request.getSession(true);

         //获取session对象，若没有获取到session对象，则返回null
         HttpSession session = request.getSession(false);
         if(session != null){
             //销毁session
             session.invalidate();
         }
     }

 }