mysql/servlet用户名密码判断是否存在数据库

最新推荐文章于 2023-04-04 00:36:02 发布

lxasmall_white

最新推荐文章于 2023-04-04 00:36:02 发布

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分类专栏： javaee 文章标签：数据库 servlet

本文链接：https://blog.youkuaiyun.com/lxasmall_white/article/details/78070188

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本文介绍了一个简单的用户登录系统的实现过程，包括数据库连接类的设计、用户属性类定义、用户登录验证接口及其实现类的开发，并展示了如何通过JSP页面接收用户输入进行登录验证。

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数据库连接类:

package com.xasmall.test;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

/**
 * 数据库连接类
 * @author 26248
 *
 */
public class DBUTtil {
    public static Connection jdbaload() {
        Properties prop=new Properties();
        Connection conn=null;
        try {
            prop.load(DBUTtil.class.getClassLoader().getResourceAsStream("config.properties"));
        } catch (IOException e1) {
            System.out.println("文件为读取成功!");
        }
        String url=prop.getProperty("url");
        String driver=prop.getProperty("driver");
        String user=prop.getProperty("user");
        String password=prop.getProperty("password");
        try {
             Class.forName(driver);
             conn=DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException e) {
            System.out.println("未加载mysql驱动!");
        } catch (SQLException e) {
            System.out.println("未连接mysql!");
        }
        if(conn!=null) {
            return conn;
        }
        else {
            throw new Error("数据库连接错误!");
        }
    }
}

用户属性类:

package com.xasmall.test;

/**
 * 用户属性类
 * @author 26248
 *
 */
public class User {
    private int id;
    private String name;
    private String password;
    /**
     * @return the id
     */
    public int getId() {
        return id;
    }
    /**
     * @param id the id to set
     */
    public void setId(int id) {
        this.id = id;
    }
    /**
     * @return the name
     */
    public String getName() {
        return name;
    }
    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }
    /**
     * @return the password
     */
    public String getPassword() {
        return password;
    }
    /**
     * @param password the password to set
     */
    public void setPassword(String password) {
        this.password = password;
    }

}

抽象接口类(方法):

package com.xasmall.test;

/**
 * @author 26248
 *
 */
public interface UserDAO {
    //创建一个login方法
    public User login(String name,String password);
}

实现接口类:

package com.xasmall.test;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**实现UserDAO接口
 * @author 26248
 *
 */
public class UserDAOImpl implements UserDAO{
    @Override
    public User login(String name, String password) {
        User user=new User();
        Connection co=DBUTtil.jdbaload();
        String sql="select id,username,password from student where username=? and password=?";
        try {
            PreparedStatement pstm=co.prepareStatement(sql);
            pstm.setString(1, name);
            pstm.setString(2, password);
            ResultSet rs=pstm.executeQuery();
            if(rs.next()) {
                user.setId(rs.getInt(1));
                user.setName(name);
                user.setPassword(password);
                return user;
            }
            else
                return null;
        } catch (SQLException e) {
            System.out.println("sql语句错误!");
        }
        return null;
    }

}

表单(jsp):

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<p>欢迎来到登陆页面<p><br>
<form action="MyLogin" method="post">
Username:<input type="text" name="username"><br>
Password:<input type="password" name="password"><br>
<input type="submit" value="提交">
</form>
</body>
</html>

数据库属性文件(properties):
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/?
user=root
password=?

判断操作类:

package com.xasmall.test;

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


@WebServlet(urlPatterns= {"/MyLogin"})
public class MyLogin extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        UserDAO user=new UserDAOImpl();
        User userLogin=user.login(request.getParameter("username"), request.getParameter("password"));
        if(userLogin==null) {
            System.out.println("数据库中不存在用户名密码!");
        }
        else {
            System.out.println("username:"+userLogin.getName()+"password"+userLogin.getPassword());
        }
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);
    }

}