编程杂谈---------关于jpa

第一个实例：

1，导包

2，src文件夹下，新建META-INF文件夹，其中添加配置文件persistence.xml

<?xml version="1.0"?>
<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="itcast" transaction-type="RESOURCE_LOCAL">
     <provider>org.hibernate.ejb.HibernatePersistence</provider>
	<properties>
         <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>
         <property name="hibernate.hbm2ddl.auto" value="update"/>
         <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 = "123"/>
         <property name = "hibernate.connection.url" value = "jdbc:mysql://localhost:3306/itcast?useUnicode=true&characterEncoding=UTF-8"/>
      </properties>
  </persistence-unit>
</persistence>

3，写bean类

      记住几个重要的标识，@Entity ，@Id，@GeneratedValue(strategy = GenerationType.AUTO)

package cn.itcast.bean;

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

@Entity
public class Person {
	private Integer id;
	private String name;
	
	public Person(){}
	
	public Person(String name){
		this.name = name;
	}

	@Id  @GeneratedValue
	public Integer getId() {
		return id;
	}
	
	public void setId(Integer id) {
		this.id = id;
	}
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}	
	
}

4，单元测试

package junit.test;

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

import org.junit.BeforeClass;
import org.junit.Test;

import cn.itcast.bean.Person;

public class PersonTest {
	@BeforeClass
	public static void setUpBeforeClass() throws Exception{
	}
	@Test
	public void save(){
		EntityManagerFactory factory = Persistence.createEntityManagerFactory("itcast");
		EntityManager em = factory.createEntityManager();		
		em.getTransaction().begin();
		em.persist(new Person("wanger"));
		em.getTransaction().commit();
		em.close();
		factory.close();
	}
}