java servlet在连接到数据库后不工作

Question

我对java非常陌生。所以如果我犯了愚蠢的错误，我很抱歉。我正在尝试执行servlet中的以下代码，但是在我将值提交到我在索引中创建的登录表单之后，什么也没有发生。html。另外，我还为会话创建了另一个servlet。预期的输出是重定向到我从数据库验证用户名和密码后创建的另一个jsp页面

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
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.servlet.http.HttpSession;

/**
 *
 * @author user
 */
@WebServlet(urlPatterns = {"/Login"})

public class Login extends HttpServlet {

 
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    processRequest(request,response);
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            String user_name = request.getParameter("username");
            String password = request.getParameter("password");
            try{
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://3306/hotel_management_system?useSSL=false","root","");
            //get data from user_login table
            Statement stm = (Statement) con.createStatement();
            ResultSet rs;
                rs = stm.executeQuery("select * from user_login where username='"+user_name+"' and password='"+password+"'");

            if(user_name != null && password != null){
            if(rs.next()){
                HttpSession session = request.getSession(true);
                session.putValue("username",user_name);
                response.sendRedirect(request.getContextPath()+ "/welcome.jsp");
            }else{
                out.println("Invalid user or password");
            }
            
            }else{
                out.println("Empty username or password");
            }
            con.close();
        }   catch (ClassNotFoundException | SQLException ex) {
                Logger.getLogger(Login.class.getName()).log(Level.SEVERE, null, ex);
            }
    } 
    }

    private void processRequest(HttpServletRequest request, HttpServletResponse response) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
    
  
    
}

Answer 1

你能不能也提供你的html页面，看起来你提交的页面带有

您可以更改代码并尝试以下操作：

@Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
      doGet(request, response);
    }