JavaWeb_Session-优快云博客

这篇博客介绍了JavaWeb中Session的使用。首先在SessionDemo01中展示了如何创建Session并存入Person对象，同时检查Session是否新创建。接着在SessionDemo02中演示了如何从Session中读取并打印Person对象。最后在SessionDemo03中说明了如何删除Session中的属性并注销Session。配置文件中设置了Session的默认超时时间为15分钟。

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JavaWeb_Session

1.SessionDemo01.java

package com.xb.servlet;

import com.xb.pojo.Person;

import javax.servlet.ServletException;
import javax.servlet.http.*;
import java.io.IOException;

public class SessionDemo01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //解决乱码
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        //得到session
        HttpSession session = req.getSession();

        //给session中存放东西
        session.setAttribute("name",new Person("king",1));

        //获取session的id
        String id = session.getId();

        //判断session是不是新创建的
        if (session.isNew()){
            resp.getWriter().write("session创建成功，id为:"+id);
        }else {
            resp.getWriter().write("session已经在服务器中存在了，id为:"+id);
        }

        //session创建的时候做了什么事
//        Cookie cookie = new Cookie("JSESSIONID",id);
//        resp.addCookie(cookie);

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

2.SessionDemo03.java

package com.xb.servlet;

import com.xb.pojo.Person;

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 SessionDemo02 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //解决乱码
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        //得到session
        HttpSession session = req.getSession();

        Person person = (Person) session.getAttribute("name");

        System.out.println(person.toString());
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

3.SessionDemo03.java

package com.xb.servlet;

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 {
        HttpSession session = req.getSession();
        session.removeAttribute("name");
        //手动注销session
        session.invalidate();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

4.Person.java

package com.xb.pojo;

import java.util.Objects;

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

    public Person() {
    }

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

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

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

5.web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                            http://xmlns.jcp.rog/xml/ns/javaee/web-app_4_0.xsd"
        version="4.0"
        metadata-complete="true">

<!--    设置session默认的失控时间-->
    <session-config>
<!--        15分钟后session自动失效，以分钟为单位-->
        <session-timeout>15</session-timeout>
    </session-config>

    <servlet>
        <servlet-name>SessionDemo03</servlet-name>
        <servlet-class>com.xb.servlet.SessionDemo03</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>SessionDemo03</servlet-name>
        <url-pattern>/s3</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>SessionDemo02</servlet-name>
        <servlet-class>com.xb.servlet.SessionDemo02</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>SessionDemo02</servlet-name>
        <url-pattern>/s2</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>SessionDemo01</servlet-name>
        <servlet-class>com.xb.servlet.SessionDemo01</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>SessionDemo01</servlet-name>
        <url-pattern>/s1</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>CookieDemo01</servlet-name>
        <servlet-class>com.xb.servlet.CookieDemo01</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>CookieDemo01</servlet-name>
        <url-pattern>/c1</url-pattern>
    </servlet-mapping>
</web-app>