spring + jpa + hibernate

1. 添加依赖Jar文件。除了必要的spring和Hibernate依赖外，下面的jar必不可少， 否则会抛出异常“No Persistence provider for EntityManager named *”

<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>4.2.8.Final</version>
		</dependency>

2. spring-jpa-hibernate.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	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-3.2.xsd
	http://www.springframework.org/schema/context
	http://www.springframework.org/schema/context/spring-context-3.2.xsd
	http://www.springframework.org/schema/aop
	http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
	http://www.springframework.org/schema/tx
	http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">

	<!-- scan all beans and inject dependence -->
	<context:component-scan base-package="com.myproject"/>
	<!-- add aop support -->
	<aop:aspectj-autoproxy/>

	<!-- jpa -->
	<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
		<property name="persistenceUnitName" value="example"/>
	</bean>

	<!-- add Transaction support -->
	<bean id="txManager" class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory"/>
	</bean>
	<!-- scan transaction annotation -->
	<tx:annotation-driven transaction-manager="txManager"/>

</beans>

3. 在类路径下创建文件夹“META-INF”， 加入文件persistence.xml。 完整的路径是 classpath:META-INF/persistence.xml, 这是jpa的默认配置文件。

<?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_2_0.xsd" version="2.0">
  <persistence-unit name="example" transaction-type="RESOURCE_LOCAL">
      <properties>
         <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>
         <property name="hibernate.connection.driver_class" value="org.gjt.mm.mysql.Driver"/>
         <property name="hibernate.connection.username" value="root"/>
         <property name="hibernate.connection.password" value="admin"/>
         <property name="hibernate.connection.url" value="jdbc:mysql://szOIBnchmrkAP1:3306/test?useUnicode=true&characterEncoding=UTF-8"/>
         <property name="hibernate.max_fetch_depth" value="3"/>
         <!-- create table automatically? -->
         <property name="hibernate.hbm2ddl.auto" value="update"/>
      </properties>
  </persistence-unit>
</persistence>

4. Entity对象

package com.myproject.example.vo;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class Account {
	@Id
	@GeneratedValue //generated automatically
	private long id;

	@Column(length=20, nullable=false)
	private String username;

	@Column(length=20, nullable=false)
	private String password;


	public long getId() {
		return id;
	}
	public void setId(long id) {
		this.id = id;
	}

	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}

}

5.Dao文件

package com.myproject.example.dao.jpa;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import org.springframework.stereotype.Repository;

import com.myproject.example.dao.AccountDao;
import com.myproject.example.vo.Account;

@Repository
public class AccountDaoBean implements AccountDao {

	@PersistenceContext
	EntityManager em;

	@Override
	public Account queryAccountById(int id) {
		return em.find(Account.class, id);
	}

	@SuppressWarnings("unchecked")
	@Override
	public List<Account> queryAccount(Account account) {
		Query q = em.createQuery("select a from Account a where a.username like ?");
		q.setParameter(1, "%"+account.getUsername()+"%");
		return q.getResultList();
	}

	@Override
	public int updateAccount(Account account) {
		em.merge(account);
		return 0;
	}

	@Override
	public int insertAccount(Account account) {
		em.persist(account);
		return 0;
	}

	@Override
	public int deleteAccount(int id) {
		em.remove(em.getReference(Account.class, id));
		return 0;
	}

}

6. Service对象包含事务管理

package com.myproject.example.service;

import java.util.List;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import com.myproject.example.dao.AccountDao;
import com.myproject.example.vo.Account;

@Service
@Transactional
public class AccountService {

	@Resource
	private AccountDao accountDao;

	//don't need to add transaction in query method 
	@Transactional(propagation=Propagation.NOT_SUPPORTED)
	public Account Login(String username, String password){
		System.out.println(username + " want  to login.");
		Account account = new Account();
		account.setUsername(username);
		account.setPassword(password);
		List<Account> list=  accountDao.queryAccount(account);
		if(list.size()==1)
			return list.get(0);
		else 
			return null;
	}

	//in method which already has "throws", we must add rollbackFor if want to rollback for this exception,
	//otherwise the method will not be rollback
	@Transactional(rollbackFor=Exception.class)
	public void reqister(Account account) {
		accountDao.insertAccount(account);
		//throw new RuntimeException("==no register");
	}

}

7.web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

	<context-param>
		<!-- location of spring config -->
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:spring.xml</param-value>
	</context-param>
	<!-- initialize spring context-->
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>

	<servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
    	<welcome-file>/jsp/index.jsp</welcome-file>
    </welcome-file-list>


   <!-- 解决因EntityManager关闭导致的延迟加载异常-->
    <filter>
        <filter-name>openEntityManagerInViewFilter</filter-name>
        <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class>
    </filter>
    <filter-mapping>
    	<filter-name>openEntityManagerInViewFilter</filter-name>
    	<url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

8.单元测试

	@Test
	public void test(){
		try {
			ApplicationContext ac=new ClassPathXmlApplicationContext("spring-jpa-hibernate.xml");
			AccountService accountService =(AccountService)ac.getBean("accountService");

			Account account = new Account();
			account.setUsername("tom");
			account.setPassword("117");
			accountService.reqister(account);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}