CreateUserServlet.java

package net.slipp.user.web;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Set;

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.validation.ConstraintViolation;
import javax.validation.Validator;

import net.slipp.user.User;
import net.slipp.user.UserDAO;

import org.apache.commons.beanutils.BeanUtilsBean;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import core.MyValidatorFactory;

@WebServlet("/users/create")
public class CreateUserServlet extends HttpServlet {
	private static final Logger logger = LoggerFactory.getLogger(CreateUserServlet.class);

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		User user = new User();
		try {
			BeanUtilsBean.getInstance().populate(user, request.getParameterMap());
		} catch (IllegalAccessException | InvocationTargetException e1) {
			throw new ServletException(e1);
		}

		logger.debug("User : {}", user);

		Validator validator = MyValidatorFactory.createValidator();
		Set<ConstraintViolation<User>> constraintViolations = validator.validate(user);
		if (constraintViolations.size() > 0) {
			request.setAttribute("user", user);
			String errorMessage = constraintViolations.iterator().next().getMessage();
			forwardJSP(request, response, errorMessage);
			return;
		}

		UserDAO userDAO = new UserDAO();
		userDAO.addUser(user);

		response.sendRedirect("/");
	}

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