EMF.java
package guestbook;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class EMF {
private static final EntityManagerFactory emfInstance =
Persistence.createEntityManagerFactory("transactions-optional");
private EMF(){}
public static EntityManagerFactory get(){
return emfInstance;
}
}
Greeting.javapackage guestbook;
import java.util.Date;
import javax.jdo.annotations.Persistent;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.users.User;
@Entity
public class Greeting {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Key key;
private User author;
private String content;
private Date date;
public Greeting(User author, String content, Date date) {
this.author = author;
this.content = content;
this.date = date;
}
public Key getKey() {
return key;
}
public User getAuthor() {
return author;
}
public String getContent() {
return content;
}
public Date getDate() {
return date;
}
public void setAuthor(User author) {
this.author = author;
}
public void setContent(String content) {
this.content = content;
}
public void setDate(Date date) {
this.date = date;
}
}
SignServlet.javapackage guestbook;
import java.io.IOException;
import java.util.Date;
import java.util.logging.Logger;
import javax.persistence.EntityManager;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.google.appengine.api.users.User;
import com.google.appengine.api.users.UserService;
import com.google.appengine.api.users.UserServiceFactory;
public class SignServlet extends HttpServlet{
private static final Logger log = Logger.getLogger(SignServlet.class.getName());
public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException{
UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser();
String content = req.getParameter("content");
Date date = new Date();
Greeting greeting = new Greeting(user,content,date);
EntityManager em = EMF.get().createEntityManager();
try{
em.persist(greeting);
}finally{
em.close();
}
resp.sendRedirect("/test.jsp");
}
}
test.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="java.util.List" %>
<%@ page import="javax.persistence.EntityManager" %>
<%@ page import="com.google.appengine.api.users.User" %>
<%@ page import="com.google.appengine.api.users.UserService" %>
<%@ page import="com.google.appengine.api.users.UserServiceFactory" %>
<%@ page import="guestbook.Greeting" %>
<%@ page import="guestbook.EMF" %>
<html>
<body>
<head>
<link type="text/css" rel="stylesheet" href="/stylesheet/main.css" />
</head>
<%
UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser();
if (user != null) {
%>
<p>Hello, <%= user.getNickname() %>! (You can
<a href="<%= userService.createLogoutURL(request.getRequestURI()) %>">sign out</a>.)</p>
<%
} else {
%>
<p>Hello!!
<a href="<%= userService.createLoginURL(request.getRequestURI()) %>">Sign in</a>
to include your name with greetings you post.</p>
<%
}
%>
<%
EntityManager em = EMF.get().createEntityManager();
String query = "select i from Greeting i";
List<Greeting> greetings = (List<Greeting>)em.createQuery(query).getResultList();
if(greetings.isEmpty()){
%>
<p>The guestbook has no messages.</p>
<%
}else{
for(Greeting g: greetings){
if(g.getAuthor() == null){
%>
<p>An anonymous person wrote:</p>
<%
} else {
%>
<p><b><%= g.getAuthor().getNickname() %></b> wrote:</p>
<%
}
%>
<blockquote><%= g.getContent() %></blockquote>
<%
}
}
em.close();
%>
<form action="/sign" method="post">
<div><textarea name="content" rows="3" cols="60"></textarea></div>
<div><input type="submit" value="Post Greeting" /></div>
</form>
</body>
</html>
