案例：自动登录，记住密码（Session+JSP）

- 日理万妓 2022-12-24 11:51 118阅读 0赞

## 用来判断cookie有没有值 ##

package com.bdit;
    
    import javax.servlet.http.Cookie;
    
    public class DBCookie {
        
        public static Cookie getCookie(Cookie[] cookies,String key){
        
            if(cookies!=null&&cookies.length>0){
        
                for(Cookie cookie:cookies){
        
                    if(cookie.getName().equals(key)){
        
                        return cookie;
                    }
                }
            }
            return null;
        }
    }

## servlet ##

package com.bdit.servlet;
    
    import com.bdit.sevice.TreeSevice;
    import com.bdit.vo.Tree;
    
    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;
    
    @WebServlet(urlPatterns = {
        "/treeServlet"})
    public class TreeServlet 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.setContentType("text/html;charset=UTF-8");
    
            String username=req.getParameter("username");
            String pass=req.getParameter("pass");
            String hobby=req.getParameter("hobby");
            String hobby2=req.getParameter("hobby2");
    
            TreeSevice sevice=new TreeSevice();
            //根据用户名和密码查找
            Tree tree=sevice.find(username,pass);
    
            if(tree!=null&&tree.getUsername().equals(username)&&tree.getPass().equals(pass)){
        
                if(hobby2!=null&&hobby2.equals("2")){
        
                if(hobby!=null&&hobby.equals("1")){
        
                    Cookie cookie1=new Cookie("username",username);
                    Cookie cookie2=new Cookie("pass",pass);
                    cookie1.setPath(req.getContextPath());
                    cookie2.setPath(req.getContextPath());
                    cookie1.setMaxAge(60*60*24);
                    cookie2.setMaxAge(60*60*24);
                    resp.addCookie(cookie1);
                    resp.addCookie(cookie2);
                    Cookie cookie3=new Cookie("hobby","checked");
                    cookie3.setPath(req.getContextPath());
                    cookie3.setMaxAge(60*60*24);
                    resp.addCookie(cookie3);
                    Cookie cookie4=new Cookie("hobby2","checked");
                    cookie4.setPath(req.getContextPath());
                    cookie4.setMaxAge(15);
                    resp.addCookie(cookie4);
                    resp.sendRedirect("success.jsp");
                }
                else{
        
                    resp.sendRedirect("success.jsp");
                }
                }else{
        
                    if(hobby!=null&&hobby.equals("1")) {
        
                        Cookie cookie1 = new Cookie("username", username);
                        Cookie cookie2 = new Cookie("pass", pass);
                        cookie1.setPath(req.getContextPath());
                        cookie2.setPath(req.getContextPath());
                        cookie1.setMaxAge(60 * 60 * 24);
                        cookie2.setMaxAge(60 * 60 * 24);
                        resp.addCookie(cookie1);
                        resp.addCookie(cookie2);
                        Cookie cookie3 = new Cookie("hobby", "checked");
                        cookie3.setPath(req.getContextPath());
                        cookie3.setMaxAge(60 * 60 * 24);
                        resp.addCookie(cookie3);
                    }else{
        
                        resp.sendRedirect("success.jsp");
                    }
                }
            }else if(tree==null){
        
                resp.sendRedirect("error.jsp");
            }
    
        }
    }

## 主页面index.jsp ##

<%--
      Created by IntelliJ IDEA.
      User: Administrator
      Date: 2020/10/20
      Time: 21:10
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <%@ page import="com.bdit.DBCookie" %>
    <html>
      <head>
        <title>$Title$</title>
      </head>
      <body>
    
      <%
          String username="";
          String pass="";
          String hobby="";
          String hobby2="";
    
        Cookie cookie4=DBCookie.getCookie(request.getCookies(),"hobby2");
        if(cookie4!=null){
        
            Cookie cookie5=DBCookie.getCookie(request.getCookies(),"hobby");
            if(cookie5!=null){
        
                Cookie cookie1= DBCookie.getCookie(request.getCookies(),"username");
                if(cookie1!=null){
        
                    username=cookie1.getValue();
                }
                Cookie cookie2=DBCookie.getCookie(request.getCookies(), "pass");
                if(cookie2!=null){
        
                    pass=cookie2.getValue();
                }
                hobby=cookie5.getValue();
            }
            hobby2=cookie4.getValue();
        }else{
        
            Cookie cookie3=DBCookie.getCookie(request.getCookies(),"hobby");
            if(cookie3!=null){
        
                Cookie cookie1= DBCookie.getCookie(request.getCookies(),"username");
                if(cookie1!=null){
        
                    username=cookie1.getValue();
                }
                Cookie cookie2=DBCookie.getCookie(request.getCookies(), "pass");
                if(cookie2!=null){
        
                    pass=cookie2.getValue();
                }
                hobby=cookie3.getValue();
            }
        }
      %>
     <form action="treeServlet" method="post">
         账号：<input type="text" name="username" value=<%=username%> ><br>
         密码：<input type="text" name="pass" value=<%=pass%> ><br>
         <input type="radio" name="hobby" <%=hobby%> value="1">记住密码<br>
         <input type="radio" name="hobby2" <%=hobby2%> value="2">自动登录<br>
         <input type="submit">
         <%
            if(hobby2.equals("checked")){
        
                response.sendRedirect("treeServlet?username="+username+"&pass="+pass+"");
            }
         %>
    
     </form>
    
      </body>
    </html>

## 成功页面success.jsp ##

<%--
      Created by IntelliJ IDEA.
      User: Administrator
      Date: 2020/10/21
      Time: 21:18
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
    <h2>登录成功</h2>
    
    <form action="index.jsp">
        <input type="submit" value="返回主页">
    </form>
    </body>
    </html>

## 失败页面error.jsp ##

<%--
      Created by IntelliJ IDEA.
      User: Administrator
      Date: 2020/10/21
      Time: 21:19
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
    <h2>登录失败</h2>
    <a href="index.jsp">回主页</a>
    </body>
    </html>