Question

如何将MySql dataBase与servlet连接到登录页面？现在在servlet中我有预定义用户名（gogikole）和密码（1234）的代码

String username = request.getParameter("username");
            String password = request.getParameter("password");

            if (username.equals("gogikole") && password.equals("1234")) {
                response.sendRedirect("mainMenu.jsp");
                return;
            }

但是如何检查用户名和密码对于数据库中的其他一些用户是否正确？例如用户名：konsta，密码：4321

我有这样的代码：

登录Servlet

package servlets;

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;
import javax.sql.*;

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

    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

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

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        if (username.equals("gogikole") && password.equals("1234")) {
            response.sendRedirect("mainMenu.jsp");
            return;
        }
    }
}

的login.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Login page</title>
</head>
<body>
<form method="post" action="LoginServlet">
    <table align="center">
        <tr>
            <td>User name</td>
            <td><input type="text" name="username"></td>
        </tr>
        <tr>
            <td>Password</td>
            <td><input type="password" name="password"></td>
        </tr>
        <tr>
            <td></td>
            <td><input type="submit" value="Login"></td>
        </tr>
    </table>
</form>
</body>
</html>

此外，我已经在Eclipse中添加了mysqlconnector。

Answer 1

首先，你应该使用MysqlConnection连接到mysql。

然后，创建一个使用sql的语句，如SELECT * FROM users WHERE username = :username AND password = :password。然后执行它。

你会得到一个包含匹配用户结果的resultSet，当然，如果用户名或密码错误，则resultSet为空。

解决问题的关键是您应该查询username.equals("gogikole") && password.equals("1234")

的数据库实例

示例：

final String DB_URL = "localhost:3306/db";  //Mysql Address
final String USER = "root";  //mysql username
final String PASS = "123456";//mysql password
final String SQL = "SELECT * FROM users WHERE username = ? AND password = ?";  //SQL
String username = request.getParameter("username");
String password = request.getParameter("password");
Connection conn = null;  //mysql connection
Statement stmt = null;   //mysql statement
Class.forName("com.mysql.jdbc.Driver");  //register driver
conn = DriverManager.getConnection(DB_URL,USER,PASS); //get connection
stmt = conn.prepareStatement(SQL); //create statement
//init param
stmt.setString(1,username);
stmt.setString(2,password);
ResultSet rs = stmt.executeQuery();  //execute query
if(rs.first()){ //finded
    response.sendRedirect("mainMenu.jsp");
    return;
}

将MySql与Servlet连接以进行登录页面

1 个答案: