Question

我正在使用JSP Servlet和MySQL数据库创建登录页面应用程序。但是我的应用程序没有显示任何错误。

package controller;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
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("/LoginController")
public class LoginController extends HttpServlet {

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

        String un=request.getParameter("user");
        String pw=request.getParameter("pass");

        // Connect to mysql(mariadb) and verify username password

        try {
            Class.forName("com.mysql.jdbc.Driver");
            // loads driver
            Connection c = DriverManager.getConnection("jdbc:mysql://localhost:3306/mylogin?" + "username=root&password="); // gets a new connection

            PreparedStatement ps = c.prepareStatement("select usernmae,password from login where username=? and password=?");
            ps.setString(1, un);
            ps.setString(2, pw);

            ResultSet rs = ps.executeQuery();

            while (rs.next()) {
                response.sendRedirect("welcome.jsp");
                return;
            }
            System.out.println("invalid user");
            return;
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }
}

Answer 1

您是否检查了服务器端日志？您的SQL语句中似乎有一个错字。您也可以尝试删除代码中的return语句。

Servlet不显示任何错误，但也不显示任何输出

1 个答案: