import javax.servlet.http .*;

import java.io.*;

import javax.servlet.*;

import java.sql.*;

public class LoginServlet extends HttpServlet{

    public void service(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{

        String errMsg = "";

        RequestDispatcher rd;

        String username = "";

        username = request.getParameter("username");

        String pass = "";

        pass = request.getParameter("pass")；

        try{

            DbDao dd = new DbDao("com.mysql.jdbc.Driver","jdbc:mysql://localhost:3306/poetry","root","root");

            ResultSet rs = dd.query("select password from t_account where account = ?",username);

            if(rs.next()){

                if(rs.getString("password").equals(pass)){

                    HttpSession session = request.getSession(true);

                    session.setAttribute("name",username);

                    rd = request.getRequestDispatcher("/welcome.jsp");

                    rd.forward(request,response);

                }else{

                    errMsg += "您的用户名密码不符合，请重新输入";

                }

            }else{

                errMsg += "您的用户名不存在，请先注册";

            }

        }catch(Exception e){

            e.printStackTrace();

        }

        if(errMsg != null &&  !errMsg.equals("")){

            rd = request.getRequestDispatcher("/login.jsp");

            request.setAttribute("err",errMsg);

            rd.forward(request,response);

        }

    }

}