ajax登录校验

Posted 2021-07-07 池鱼i_

分为  dao层     service层  servlet 层 连接数据库      jar包     连接数据库的      js        

 

UserDao代码

package cn.hp.dao;

import cn.hp.util.JDBCUtils;

import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDao {
    public int selectByAccountAndPassword(String account, String password) {
        String sql = "select count(*) from users where account=? and password=?";
        Object[] objects = {account, password};
        ResultSet resultSet =  JDBCUtils.DQL(sql,objects);
        int select=0;
       try {
           while (resultSet.next()){
             select=  resultSet.getInt(1);
           }
       }catch (SQLException e){
           e.printStackTrace();
       }
       return select;
    }

    public int selectByAccount(String account) {
        String sql = "select count(*) from users where account=? ";
        Object[] objects = {account};
        ResultSet resultSet = JDBCUtils.DQL(sql,objects);
        int select=0;
        try {
            while (resultSet.next()){
                select=  resultSet.getInt(1);
            }
        }catch (SQLException e){
            e.printStackTrace();
        }
        return select;
    }
}

 

service层代码

package cn.hp.service;

import cn.hp.dao.UserDao;

public class UserService {
    UserDao userDao= new UserDao();
    public boolean login(String account, String password) {

     int select= userDao.selectByAccountAndPassword(account,password);
      if (select>0){
          return true;
      }else {
          return false;
      }
    }

    public boolean check(String account) {

        int select= userDao.selectByAccount(account);
        if (select>0){
            return true;
        }else {
            return false;
        }
    }
}

servlet层代码

package cn.hp.servlet;

import cn.hp.service.UserService;

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

@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        //获取用户输入的内容
        String account= req.getParameter("account");
        String password= req.getParameter("password");
        //根据service来判断当前登录的账号密码是否正确

        UserService userService =new UserService();
         boolean flag=  userService.login(account,password);
         if (flag){
             req.getRequestDispatcher("success.jsp").forward(req,resp);
         }else{
             req.setAttribute("msg","密码错误请重新登录");
             req.getRequestDispatcher("login.jsp").forward(req,resp);
         }
    }
}

package cn.hp.servlet;

import cn.hp.service.UserService;

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

@WebServlet("/check")
public class CheckServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        //获取用户输入的内容
        String account= req.getParameter("account");
        //根据service来判断当前登录的账号密码是否正确
        UserService userService =new UserService();
      boolean flag= userService.check(account);
      resp.getWriter().println(flag);
        System.out.println(flag);

    }
}

 

uitl代码块

package cn.hp.util;

import java.sql.*;

public class JDBCUtils {

    static Connection connection = null ;
    static Statement statement = null ;
    static PreparedStatement preparedStatement = null ;
    static ResultSet resultSet = null ;

    static{
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/user?characterEncoding=utf8&serverTimezone=UTC", "root", "123456");
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }

//    新增和修改  DML 操作 String sql ， sql中的参数    preparedStatement   Object[] arr 用来补全sql中的?
    public static int DML(String sql , Object[] arr  ){  // 可变参数 Object ... arr  0~n个参数
        int update = 0 ;
        try{
            preparedStatement = connection.prepareStatement(sql);
//            循环完毕，会将sql中全部? 补充齐
            for (int i = 0 ; i < arr.length ; i++){
                preparedStatement.setObject(i+1 , arr[i] );
            }
            update = preparedStatement.executeUpdate();
        }catch (SQLException e){
            e.printStackTrace();
        }
        return update ;
    }

    //     带参查询  DQL 操作
    public static ResultSet DQL(String sql , Object[] arr ){
        try{
            preparedStatement = connection.prepareStatement(sql);
//            循环完毕，会将sql中全部? 补充齐
            for (int i = 0 ; i < arr.length ; i++){
                preparedStatement.setObject(i+1 , arr[i] );
            }
            resultSet = preparedStatement.executeQuery();
        }catch (SQLException e){
            e.printStackTrace();
        }
        return resultSet ;
    }

    //    单独提供关闭资源方法
    public static void close(){
        try {
            if (statement!=null){
                statement.close();
            }
            if (connection!= null){
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

}

Show.jsp代码

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登陆页面</title>
</head>
<script src="js/jquery-3.6.0.js"></script>

<body>
<form action="login">
    账号：<input id="input1" type="text" name="account">  <span id="span1"></span>     <br/>
    密码：<input type="password" name="password"><span style="color: red">${msg}</span><br/>
    <input type="submit" value="登录">
</form>
</body>
<script>
    $("#input1").blur(function () {
        let account = $("#input1").val();

        $.ajax({
            url:"check",
            type:"get",
            data:"account="+account,
            success:function (data) {
                let data1 = JSON.parse(data);
                if (data1){
                    $("#span1").html("用户名存在");
                    $("#span1").attr("style","color:green");
                }else {
                    $("#span1").html("用户名不存在");
                    $("#span1").attr("style","color:red");
                }

            }

        })

    })

</script>
</html>