Appengine部署JPA-CFANZ编程社区

Google App Engine and JPA[url]http://www.vogella.com/blog/2011/01/10/google-app-engine-jpa/[/url]
在google app engine中使用JPA [url]http://www.1zhang.com/group/viewthread.php?tid=5188[/url]

1.创建的时候,会自动增加jpa的jar.
2.src/META-INF/persistence.xml

<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
        http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
	version="1.0">
	<persistence-unit name="transactions-optional">
		<provider>org.datanucleus.api.jpa.PersistenceProviderImpl</provider>
		<properties>
			<property name="datanucleus.NontransactionalRead" value="true" />
			<property name="datanucleus.NontransactionalWrite" value="true" />
			<property name="datanucleus.ConnectionURL" value="appengine" />
		</properties>
	</persistence-unit>
	<persistence-unit name="eventual-reads-short-deadlines">
		<provider>org.datanucleus.store.appengine.jpa.DatastorePersistenceProvider</provider>
		<properties>
			<property name="datanucleus.NontransactionalRead" value="true" />
			<property name="datanucleus.NontransactionalWrite" value="true" />
			<property name="datanucleus.ConnectionURL" value="appengine" />

			<property name="datanucleus.appengine.datastoreReadConsistency"
				value="EVENTUAL" />
			<property name="javax.persistence.query.timeout" value="5000" />
			<property name="datanucleus.datastoreWriteTimeout" value="10000" />
		</properties>
	</persistence-unit>
</persistence>

3.Pojo

package com.gae.pandy.pojo;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class Todo {
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Long todoId;
	private String summary;

	public String getSummary() {
		return summary;
	}

	public void setSummary(String summary) {
		this.summary = summary;
	}
}

4.service

package com.gae.pandy.service;

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public class EMFService {
    private static final EntityManagerFactory emfInstance = Persistence
            .createEntityManagerFactory("transactions-optional");

    private EMFService() {
    }

    public static EntityManagerFactory get() {
        return emfInstance;
    }
}

5.servlet

package com.gae.pandy.controller;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Query;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gae.pandy.pojo.Todo;
import com.gae.pandy.service.EMFService;

@SuppressWarnings("serial")
public class PersistsServlet extends HttpServlet {
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws IOException {
        this.doPost(req, resp);
    }

    public void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws IOException {
        Todo todo = new Todo();

        todo.setSummary("This is my todo");

        EntityManager em = EMFService.get().createEntityManager();
        List<Todo> todos = null;
        try {
            em.persist(todo);//增加到数据库
            Query q = em.createQuery("select t from Todo t");
            todos = new ArrayList(q.getResultList());
        } finally {
            em.close();
        }

        resp.setContentType("text/plain");
        if (todos != null) {
            resp.getWriter().println(
                    "Hello, JPA. We have " + todos.size()
                            + " number of entries.");
        } else {
            resp.getWriter().println("Should not happen");
        }
    }
}

6.web.xml

<servlet>
		<servlet-name>PersistsServlet</servlet-name>
		<servlet-class>com.gae.pandy.controller.PersistsServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>PersistsServlet</servlet-name>
		<url-pattern>/PersistsServlet</url-pattern>
	</servlet-mapping>

执行:[url]http://localhost:8888/PersistsServlet[/url]

aopalliance-1.0.jar

appengine-api-1.0-sdk-1.7.4.jar

appengine-api-labs.jar

appengine-endpoints.jar

appengine-jsr107cache-1.7.4.jar

apps-marketplace.jar

asm-4.0.jar

commons-logging-1.1.1.jar

datanucleus-api-jdo-3.1.1.jar

datanucleus-api-jpa-3.1.1.jar

datanucleus-appengine-2.1.1.jar