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();
        }
    }
    
    
}