JAVAWEB session重点

最新推荐文章于 2023-03-11 22:44:17 发布

原创最新推荐文章于 2023-03-11 22:44:17 发布 · 134 阅读

CC 4.0 BY-SA版权

本文深入解析了Session和Cookie的工作原理及区别，阐述了如何在Java Servlet中使用HttpSession存储和检索用户信息，包括用户登录状态和购物车信息的管理。同时，介绍了Session的创建、使用及注销过程。

session会对每一个用户（浏览器）创建一个session对象
一个session独占一个浏览器，只要浏览器没关，这个session就存在；
cookie有限session可以放多个，
只要用户登录，整个浏览器都会访问—》保存用户信息======》购物车信息
cookie和session的区别

 @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");
        //得到一个session
        HttpSession session = req.getSession();
        //给session中存东西
        session.setAttribute("name","徐源");
        //获取session的ID
        String id = session.getId();
        //判读是否是新的
        if (session.isNew()){
            resp.getWriter().write("session创建成功,id为:"+id);
        }else {
            resp.getWriter().write("session已经创建,id为:"+id);
        }

    <servlet>
        <servlet-name>sessionDemo</servlet-name>
        <servlet-class>com.xuyuan.demo.sessionDemo</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>sessionDemo</servlet-name>
        <url-pattern>/session</url-pattern>
    </servlet-mapping>

servletdemo2：

package com.xuyuan.demo;

import com.xuyuan.demo.pojo.Person;

import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;

public class sessionDemo2 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");
        //得到一个session
        HttpSession session = req.getSession();
        //给session中存东西
        Person person = (Person) session.getAttribute("name");
        System.out.println(person.toString());
    }

}

实体类

package com.xuyuan.demo.pojo;

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    public void setAge(int age) {
        this.age = age;
    }
}

注销session

package com.xuyuan.demo;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

public class sessionDemo03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        HttpSession session = req.getSession();
        session.removeAttribute("name");
        session.invalidate();//注销
    }
}

一个浏览器对应一个session对象

    </servlet-mapping>
    <session-config>
<!--session的时间设置分钟自动失效，一般用手动操作-->
            <session-timeout>15</session-timeout>
    </session-config>

</web-app>