JSP与Servlet(三)：Cookie和Session

一.JSP之Cookie

1.cookie实现思维导图

2.jsp页面实例

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
    Cookie user = new Cookie("user","hly");
    Cookie password = new Cookie("password","123");
        /*设置有效期*/
    user.setMaxAge(60*60);
    password.setMaxAge(60*60);
        /*添加cookie*/
    response.addCookie(user);
    response.addCookie(password);
%>
<html>
<head>
    <title>coolie</title>
</head>
<body>
<%
    /*获得所有cookie*/
    Cookie[] cookies = request.getCookies();
   for(int i = 0 ;i<cookies.length;i++){
       out.println(cookies[i].getName()+" "+cookies[i].getValue());
       if(cookies[i].getName().compareTo("message")==0){
           cookies[i].setMaxAge(0);
           /*google设置路径才能删除*/
           cookies[i].setPath("/");
           response.addCookie(cookies[i]);
           out.println("已将删除cookie:"+cookies[i].getName());
       }
   }

%>

</body>
</html>

3.cookie保存表单数据实例

前端jsp页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>myCookie</title>
</head>
<body>

<form action="/MyCookie" method="get">
    <input type="text" placeholder="userId" name="userId">
    <input type="text" placeholder="userPassword" name="userPassword">
    <input type="submit" value="提交">
</form>

</body>
</html>

后端Servlet接收数据，然后就能在cookie里面查找到数据了

package com.hly.jsp.cookie;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * @author :hly
 * @github :github.com/SiriusHly
 * @blog :blog.csdn.net/Sirius_hly
 * @date :2018/8/18
 */
@WebServlet("/MyCookie")
public class MyCookie extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {

        String userId = request.getParameter("userId");
        String userPassword = request.getParameter("userPassword");
        System.out.println(userId+" "+userPassword);
        /*创建cookie对象*/
        Cookie  id= new Cookie("id",userId);
        Cookie password = new Cookie("pw",userPassword);
        id.setMaxAge(60);
        password.setMaxAge(60);
       /*添加cookie*/
        response.addCookie(id);
        response.addCookie(password);

        PrintWriter out = response.getWriter();
        out.println("success");

    }

    public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException {
        doGet(request,response);
    }

}

二.JSP值Session

1.session思维导图

2.session代码实例

页面运行时应先执行以下页面代码，当用户第一次浏览网页后，session的值就会发生改变，如果获取一个空的session值，就会出现500报错。

<%@ page import="java.util.Date" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
    Date createTime = new Date(session.getCreationTime());
    Date lastTime = new Date(session.getLastAccessedTime());
    Integer visitNum = 0;
    
    if(session.isNew()){
        session.setAttribute("visitNum",visitNum);
    }
    else{
        visitNum = (Integer) session.getAttribute("visitNum");
        /*词句需要放在一开始运行的网页，不然会出现空指针报错*/
        visitNum+=1;
        session.setAttribute("visitNum",visitNum);
    }
%>
<html>
<head>
    <title>mySession</title>
</head>
<body>
<form action="session.jsp" method="get">
    <input type="text" placeholder="userId" name="userId">
    <input type="submit" value="提交">
</form>
</body>
</html>

跳转到的页面为:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="java.io.*,java.util.*" %>
<%
    String userId = request.getParameter("userId");
    Integer visitNum = (Integer) session.getAttribute("visitNum");
%>
<html>
<head>
    <title>session</title>
</head>
<body>
欢迎<%=userId%>第<%=visitNum%>次访问!
</body>
</html>

JSP与Servlet(三)：Cookie和Session

一.JSP之Cookie

1.cookie实现思维导图

2.jsp页面实例

3.cookie保存表单数据实例

二.JSP值Session

1.session思维导图

2.session代码实例

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