AppEngine整合Spring+JPA

STEP 1. 事前準備
1. 先準備AppEngine SDK1.3.5版以上
2. 本範例是用Spring 2.5, 建議是用一樣的版本, 比較不會有問題,下載之後把下面這些JAR檔, 放到Lib裡

• aspectjrt.jar
• aspectjweaver.jar
• cglib-nodep-2.1_3.jar
• commons-logging-1.0.4.jar
• spring.jar

STEP 2. 建立Entity, DAO, Servlet
1. 建立本範例中的Entity: fattom.riddle.entity.User

package fattom.riddle.entity;

import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class User implements Serializable{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

2.建立DAO: fattom.riddle.dao.UserDao

package fattom.riddle.dao;

import java.util.List;
import org.springframework.orm.jpa.support.JpaDaoSupport;
import fattom.riddle.entity.User;

public class UserDao extends JpaDaoSupport {

    public void persist(Object user) {
        this.getJpaTemplate().persist(user);
    }
 
    public void remove(Object user) {
        User result = this.getJpaTemplate().find(User.class, ((User)user).getId());
        if(result != null)
            this.getJpaTemplate().remove(result);
    }
    @SuppressWarnings("unchecked")
    public void removeAll() {
        List result = this.getJpaTemplate().find("select e from fattom.riddle.entity.User e");
        for(Object user:result) {
            this.getJpaTemplate().remove((User)user);
        }
    }

    @SuppressWarnings("unchecked")
    public List findAll() {
        List result = this.getJpaTemplate().find("select e from fattom.riddle.entity.User e");
        result.size();
        return result;
    }
}

3. 建立Servlet: fattom.riddle.TestAction

package fattom.riddle;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import fattom.riddle.dao.UserDao;
import fattom.riddle.entity.User;

@SuppressWarnings("serial")
public class TestAction extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws IOException {

        PrintWriter out = response.getWriter();
        response.setContentType("text/plain");

        ApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(getServletContext());
        UserDao userDao = (UserDao) context.getBean("userDao");

        if (request.getParameter("name") != null) {
            User tmpUser = new User();
            tmpUser.setName(request.getParameter("name"));
            userDao.persist(tmpUser);
        
        }

        List users = userDao.findAll();
        for (Object user : users) {
            out.println(((User)user).getId() + "/" + ((User)user).getName());
        }
    
        if (request.getParameter("action") != null && "delete".equals(request.getParameter("action"))) {
            for (Object user : users) {
                userDao.remove((User)user);
            }
        }

        out.println("Hello, GAE and Spring world");
    }
}

STEP 3. 設定相關XML
1. 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.store.appengine.jpa.DatastorePersistenceProvider</provider>
        <properties>
            <property name="datanucleus.NontransactionalRead" value="true"/>
            <property name="datanucleus.NontransactionalWrite" value="true"/>
            <property name="datanucleus.ConnectionURL" value="appengine"/>
        </properties>
    </persistence-unit>

</persistence>


2. WEB-INF/applicationContext.xml

 <?xml version="1.0" encoding="UTF-8"?>
<beans default-autowire="byName"
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean" >
        <property name="persistenceUnitName" value="transactions-optional"/>
    </bean>
  
    <bean id="transactionManager"
        class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

  <aop:config proxy-target-class="true">
        <aop:advisor pointcut="execution(* fattom.riddle..dao.*.*(..))" advice-ref="txAdvice"/>
    </aop:config>
    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="*" propagation="REQUIRED" />
        </tx:attributes>
    </tx:advice>
    <bean id="userDao" class="fattom.riddle.dao.UserDao" scope="singleton">
    </bean>
</beans>


3. WEB-INF/web.xml

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
<listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
<servlet>
<servlet-name>Test</servlet-name>
<servlet-class>fattom.riddle.TestAction</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Test</servlet-name>
<url-pattern>/test</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>


最後, 再寫個 index.html 就可以測試看看有沒有成功囉

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <title>Hello App Engine</title>
  </head>

  <body>
    <h1>Hello App Engine!</h1>
<form action="test" method="get">
add new user, name = <input type="text" name="name"></input>
<input type="submit" value="OK"></input>
</form>
<br>
<a href="./test?action=delete">delete all users</a>
</br>
  </body>
</html>