java mysql页面登录

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

public class LoginServlet extends HttpServlet {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/mydatabase";
    private static final String USER = "username";
    private static final String PASS = "password";

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

        try {
            Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
            PreparedStatement stmt = conn.prepareStatement("SELECT * FROM users WHERE username=? AND password=?");
            stmt.setString(1, username);
            stmt.setString(2, password);
            ResultSet rs = stmt.executeQuery();

            if (rs.next()) {
                response.sendRedirect("welcome.jsp");
            } else {
                response.sendRedirect("login.jsp?error=1");
            }
        } catch (SQLException e) {
            throw new ServletException("Database access error", e);
        }
    }
}