loginservlet示例代码

Question

Servlets和jsp对我来说是新手，所以我开始查看登录servlet的示例代码。是否有新玩家插入到gamelogic中，因为这个servlet实际上应该有效？我只能看到正在处理的错误。

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.RequestDispatcher;
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 de.ustg.quiz.application.*;
import de.ustg.quiz.error.*;


//Servlet Implementation

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

public void init() {

}   

//@see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse       response)

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("doPost");
    Quiz quiz = Quiz.getInstance();
    QuizError quizError = new QuizError(); 
    response.setContentType("text/html;charset=UTF-8");

    //insert player into gamelogic
    if(request.getParameter("username").equals("")) {
        request.setAttribute("LoginError", true);
        request.setAttribute("LoginErrorMessage", "username required");
    } else {
        if(quiz.createPlayer((String) request.getParameter("username"), quizError) == null) {
            System.out.println(quizError.getDescription());
            request.setAttribute("LoginError",true);
            request.setAttribute("LoginErrorMessage", quizError.getDescription());
        }
    }
    // write player frome gamelogic into list
    List<Player> playerList = new ArrayList<Player>(quiz.getPlayerList());
    request.setAttribute("playerList", playerList);
    RequestDispatcher requestDispatcher = request.getRequestDispatcher("index.jsp");
    requestDispatcher.forward(request, response);

}

}