保存会话技术Session

1.如何实现在不同的页面可以查看信息（购物车），同时实现信息独有

Session生命周期默认30分钟

Session1.java

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Session1
 */
@WebServlet("/Session1")
public class Session1 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Session1() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("tesxt/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
        //访问Session 当没有Session时候自动创建
        HttpSession session=request.getSession();
        //给该Session创建属性 创建两个Sesion
        session.setAttribute("uname", "宋江");
        session.setAttribute("age", "100");
        //生命周期默认30分钟
        out.print("创建Session,并放入了一个属性");
        
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Session2
 */
@WebServlet("/Session2")
public class Session2 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Session2() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("tesxt/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
        //访问Session 当没有Session时候自动创建
        HttpSession session=request.getSession();
        //获取Session
        String usname=(String)session.getAttribute("uname");
        if(usname!=null){
        System.out.println("session name="+usname);}
        else {
            out.print("没有uname");
        }
        
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

删除;

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Session2
 */
@WebServlet("/Session2")
public class Session2 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Session2() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("tesxt/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
        //访问Session 当没有Session时候自动创建
        HttpSession session=request.getSession();
        //获取Session
        String usname=(String)session.getAttribute("uname");
        if(usname!=null){
        System.out.println("session name="+usname);}
        else {
            out.print("没有uname");
        }
        
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

重置直接覆盖就行

存放在服务器内存,默认生命周期30分钟

代码示例：

示例1：

Session1.java

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Servlet1
 */
@WebServlet("/Servlet1")
public class Servlet1 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet1() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
//        out.print("<h1>大家好</h1>");
        //访问session  当发现没有的时候会自动创建
        HttpSession session=request.getSession();
        session.setAttribute("uname", "宋江");
        session.setAttribute("age", "100");
        out.print("创建sesssion放置属性");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

Session2.java

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Servlet2
 */
@WebServlet("/Servlet2")
public class Servlet2 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet2() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
        //获取Session
        HttpSession session=request.getSession();
        //获取
        String uname=(String) session.getAttribute("uname");
        String age=(String) session.getAttribute("age");
        if(uname==null){
            out.println("没有获取到数据");        
        }else{
            out.println("session uname="+uname);            
        }

        
        //
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

同一个用户浏览器向服务器传送session,名字相同时就是替换（更新）

最终实现代码：

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Servlet1
 */
@WebServlet("/Servlet1")
public class Servlet1 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet1() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
//        out.print("<h1>大家好</h1>");
        //访问session  当发现没有的时候会自动创建
        HttpSession session=request.getSession();
        session.setAttribute("uname", "宋江");
        session.setAttribute("age", "100");
        //创建一个对象
      User user=new User();
      user.setName("小猫");
      user.setColor("红色");
      session.setAttribute("cat", user);
        out.print("创建sesssion放置属性");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Servlet2
 */
@WebServlet("/Servlet2")
public class Servlet2 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet2() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
        //获取Session
        HttpSession session=request.getSession();
        //获取
        String uname=(String) session.getAttribute("uname");
        String age=(String) session.getAttribute("age");
        User user=(User) session.getAttribute("cat");
        if(user!=null){
            out.print("猫的名字颜色"+user.getName()+user.getColor());
            
        }
        if(uname==null){
            out.println("没有获取到数据");        
        }else{
            out.println("session uname="+uname);            
        }

        
        //
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

package com.session;

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Servlet3
 */
@WebServlet("/Servlet3")
public class Servlet3 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet3() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
        HttpSession session=request.getSession();
        session.setAttribute("uname", "张三");
        out.print("重新设置Uname");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

package com.session;
//实现删除session功能
import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class Servlet4
 */
@WebServlet("/Servlet4")
public class Servlet4 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet4() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
        HttpSession session=request.getSession();
        session.removeAttribute("uname");
        out.print("删除 uname");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

View Code

User.java

package com.session;

public class User {
private String name;
private String color;
/**
 * @return the name
 */
public String getName() {
    return name;
}
/**
 * @param name the name to set
 */
public void setName(String name) {
    this.name = name;
}
/**
 * @return the color
 */
public String getColor() {
    return color;
}
/**
 * @param color the color to set
 */
public void setColor(String color) {
    this.color = color;
}

}

View Code

相关阅读:
检索 COM 类工厂中 CLSID 为 {00024500-0000-0000-C000-000000000046} 的组件失败的解决方案--报错80080005
c# 数组拼接、DataTable拼接
 【C#】数据类型（sbyte，byte，short，ushort，int，uint，long，ulong和char。、、、）
一个字符占几个字节
 js获取不到scrollTop值的问题
 省市县2020年最新更新
 【警惕流文件转string存数据库操作】记一次数据库异常增长的排查经历
 【VS Code】利用Live Server插件搭建本地服务
 数据库中float类型存储时位数增多问题
 【小工具】阿里云视频上传工具
原文地址：https://www.cnblogs.com/helloworld2019/p/11038114.html