JPA+Spring之HelloWorld

第一步：新建一个web项目，导入相关的Jar文件（需要导入commans-logging.jar）；

第二步：在src下新建META-INF/persistance.xml；

第三步：编写实体类Person.java；

第四步：编写Dao接口PersonDao.java和实现类PersonDaoImpl.java；

第五步：编写applicationContext.xml:

第六步：编写测试类

 

persistence.xml代码：

 

<?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="MySQLProduction" transaction-type="RESOURCE_LOCAL">
		<properties>
			<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" />

			<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
			<property name="hibernate.connection.username" value="root" />
			<property name="hibernate.connection.password" value="root" />
			<property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/mydb" />
			<property name="hibernate.max_fetch_depth" value="5" />
			<property name="hibernate.jdbc.fetch_size" value="20" />
			<property name="hibernate.jdbc.batch_size" value="10" />

			<property name="hibernate.hbm2ddl.auto" value="update" />
			<property name="hibernate.show_sql" value="true" />
			<property name="hibernate.format_sql" value="false" />
		</properties>
	</persistence-unit>
</persistence>

 

 applicationContext.xml代码：

 

<?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-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-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">

	<context:component-scan base-package="*"></context:component-scan>
	
	<bean id="entityManagerFactory"
		class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
		<property name="persistenceUnitName" value="MySQLProduction"/>
	</bean>

	<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory" />
	</bean>
	<tx:annotation-driven transaction-manager="transactionManager" />
	
	<bean id="personDao" class="dao.PersonDaoImpl">
		<property name="entityManagerFactory" ref="entityManagerFactory"/>
	</bean>
	
	<bean id="personDaoByAnno" class="dao.PersonDaoImpl1"/>
</beans>

 

 Person.java代码：

 

package domain;

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

@Entity
@Table(name="person")
public class Person {
	private Integer id;
	private String name;
	
	public Person(String name) {
		super();
		this.name = name;
	}
	public Person() {
		super();
	}
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	@Column(name="name")
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	
	
}

  PersonDao.java代码：

 

package dao;

import domain.Person;

public interface PersonDao {
	void save(Person person) throws Exception;
}

  PersonDaoImpl.java代码：

 

package dao;

import org.springframework.orm.jpa.support.JpaDaoSupport;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import domain.Person;

public class PersonDaoImpl extends JpaDaoSupport implements PersonDao {

	@Transactional(readOnly=false,propagation=Propagation.REQUIRED)
	public void save(Person person) throws Exception {
		getJpaTemplate().persist(person);
	}

}

实现类如果用标注还可以这样写：

 

package dao;

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

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

import domain.Person;
@Repository(value="personDaoByAnno")
public class PersonDaoImpl1 implements PersonDao {

	private EntityManager em;
	
	@PersistenceContext(unitName="MySQLProduction")
	public void setEm(EntityManager em) {
		this.em = em;
	}

	@Transactional(readOnly=false,propagation=Propagation.REQUIRED)
	public void save(Person person) throws Exception {
		em.persist(person);
	}
	
}

 

测试类代码：

 

package test;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import dao.PersonDao;
import domain.Person;

public class PersonTest {
	@Test
	public void save() throws Exception{
		ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
		//PersonDao dao = (PersonDao) ac.getBean("personDao");
		PersonDao dao = (PersonDao) ac.getBean("personDaoByAnno");
		dao.save(new Person("Hello World"));
	}
}

  注意：事务默认是不提交的，如果spring不对事务处理，运行没有问题，但数据库中没有值！