SignGuestbookServlet.java

package com.ziqewgww.web;

import java.io.IOException;
import java.util.Date;
import java.util.logging.Logger;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;
import com.google.appengine.api.users.User;
import com.google.appengine.api.users.UserService;
import com.google.appengine.api.users.UserServiceFactory;

public class SignGuestbookServlet extends HttpServlet{
	private static final Logger log = Logger.getLogger(SignGuestbookServlet.class.getName());

    public void doPost(HttpServletRequest req, HttpServletResponse resp)
                throws IOException {
    	 UserService userService = UserServiceFactory.getUserService();
         User user = userService.getCurrentUser();

         // We have one entity group per Guestbook with all Greetings residing
         // in the same entity group as the Guestbook to which they belong.
         // This lets us run a transactional ancestor query to retrieve all
         // Greetings for a given Guestbook.  However, the write rate to each
         // Guestbook should be limited to ~1/second.
         String guestbookName = req.getParameter("guestbookName");
         Key guestbookKey = KeyFactory.createKey("Guestbook", guestbookName);
         String content = req.getParameter("content");
         Date date = new Date();
         Entity greeting = new Entity("Greeting", guestbookKey);
         greeting.setProperty("user", user);
         greeting.setProperty("date", date);
         greeting.setProperty("content", content);

         DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
         datastore.put(greeting);
         RequestDispatcher rd = req.getRequestDispatcher("WEB-INF/jsp/guest/main.jsp");
 		 try {
			rd.forward(req, resp);
		} catch (ServletException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
    }

}