LoginServlet.java

package net.slipp.user.web;

import java.io.IOException;

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 javax.servlet.http.HttpSession;

import net.slipp.user.PasswordMismatchException;
import net.slipp.user.User;
import net.slipp.user.UserNotFoundException;

@WebServlet("/users/login")
public class LoginServlet extends HttpServlet {
	public static final String SESSION_USER_ID = "userId";

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String userId = request.getParameter("userId");
		String password = request.getParameter("password");
		
		try {
			User.login(userId, password);
			HttpSession session = request.getSession();
			session.setAttribute(SESSION_USER_ID, userId);
			response.sendRedirect("/");
		} catch (UserNotFoundException e) {
			forwardJSP(request, response, "존재하지 않는 사용자 입니다. 다시 로그인하세요.");
		} catch (PasswordMismatchException e) {
			forwardJSP(request, response, "비밀번호가 틀립니다. 다시 로그인하세요.");
		}
	}

	private void forwardJSP(HttpServletRequest request,
			HttpServletResponse response, String errorMessage) throws ServletException, IOException {
		request.setAttribute("errorMessage", errorMessage);
		RequestDispatcher rd = request.getRequestDispatcher("/login.jsp");
		rd.forward(request, response);
	}
}