Java Servlet Cookie登录状态检测

最新推荐文章于 2024-07-03 21:03:50 发布

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最新推荐文章于 2024-07-03 21:03:50 发布

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分类专栏： note 文章标签： java

本文链接：https://blog.youkuaiyun.com/YiLiXiaoHuiChen/article/details/83930852

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这个博客介绍了如何使用Java Servlet结合Cookie实现用户登录状态管理。通过`GetCookie.java`检查用户是否已登录，`ClearCookie.java`用于清除Cookie，`ShowCookie.java`展示Cookie信息。用户在`login.jsp`页面输入用户名和密码后，登录状态会通过Cookie存储，并根据Cookie信息重定向到相应页面。

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index.jsp

login.jsp

<%--
  Created by IntelliJ IDEA.
  User: adler
  Date: 2018/11/9
  Time: 7:09 PM
  To change this template use File | Settings | File Templates.
--%>
<%@ pagecontentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>用户登录系统</title>
  </head>
  <body>
  <form method="post" target="_blank" action="/Servlet">
    用户名:<input type="text" name="name"/>
    <br>
    密码:<input type="password" name="passwd"/>
    <button type="submit">登录</button>
  </form>
  <br>
  <form method="post" target="_blank" action="/GetCookie">
    <button type="submit">登录状态检测</button>
  </form>
  <form method="post" action="/ClearCookie">
    <button type="submit">清除Cookie</button>
  </form>
  <form method="post" action="/ShowCookie">
    <button type="submit">查看Cookie</button>
  </form>
  </body>
</html>

red.jsp

<%--
  Created by IntelliJ IDEA.
  User: adler
  Date: 2018/11/10
  Time: 12:12 PM
  To change this template use File | Settings | File Templates.
--%>
<%@ pagecontentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>欢迎回来!</h1>
<a href="/ClearCookie">注销登录</a>
</body>
</html>

login.jsp重定向到:>>GetCookie.java<<判断是否已经登录过(有Cookie信息)

import javax.servlet.ServletException;
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;
import java.net.URLDecoder;

@WebServlet("/GetCookie")
public class GetCookie extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setHeader("Content-type", "text/html;charset=UTF-8");
        PrintWriter out = resp.getWriter();
        Cookie cookie = null;
        Cookie[] cookies = null;
        cookies = req.getCookies();
        String title = "Delete Cookie Example";
        String docType = "<!DOCTYPE html>\n";
        out.println(docType +
                "<html>\n" +
                "<head><title>" + title + "</title></head>\n" +
                "<body bgcolor=\"#f0f0f0\">\n");
        if (cookies != null) {
            out.println("<h2>Cookie 名称和值</h2>");
            for (int i = 0; i < cookies.length; i++) {
                cookie = cookies[i];
                out.print("名称：" + cookie.getName() + "，");
                out.print("值：" + URLDecoder.decode(cookie.getValue(), "utf-8") + " <br/>");
                String str = URLDecoder.decode(cookie.getValue(),"utf-8");
                if (str.equals("null")) {
                    resp.sendRedirect("/login.jsp"); //如果没登录跳转到主界面
                    break;
                } else {
                    resp.sendRedirect("/red.jsp");
                    break;
                }
            }
        }
    }

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

ClearCookie.java

ShowCookie.java

import javax.servlet.ServletException;
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;
import java.net.URLDecoder;

@WebServlet("/ShowCookie")
public class ShowCookie extends HttpServlet {
   @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setHeader("Content-type", "text/html;charset=UTF-8");
        PrintWriter out = resp.getWriter();
        Cookie cookie = null;
        Cookie[] cookies = null;
        cookies = req.getCookies();
        String title = "Delete Cookie Example";
        String docType = "<!DOCTYPE html>\n";
        out.println(docType +
                "<html>\n" +
                "<head><title>" + title + "</title></head>\n" +
                "<body bgcolor=\"#f0f0f0\">\n");
        if (cookies != null) {
            out.println("<h2>Cookie 名称和值</h2>");
            for (int i = 0; i < cookies.length; i++) {
                cookie = cookies[i];
                out.print("名称：" + cookie.getName() + "，");
                out.print("值：" + URLDecoder.decode(cookie.getValue(), "utf-8") + " <br/>");
            }
        }
    }

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