JPA入门（Hibernate）

最新推荐文章于 2024-10-18 08:30:00 发布

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#Hibernate #JPA #MySQL #JDBC #XML

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1 篇文章

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本文介绍如何在Eclipse中整合Hibernate实现简单的JPA应用。包括项目搭建步骤、实体类定义、持久化操作及配置文件设置等关键内容。

1.1 eclipse 3.6.2

1.2 hibernate3.6.1 http://sourceforge.net/projects/hibernate/files/hibernate3/3.6.1.Final/

这里包含了所有需要的东东

/jpa/**

/required/**

hibernate3.jar

1.3 mysql 5.5.9

2.1 创建一个java project

注意：必须手工添加 persistence.xml，如果创建的是JPA project那么ec会自动创建，与openJPA入门篇一不一样的是这里选择配置的Hibernate Libraries

3.1

/**

 *  Copyright(c) 2010-2011 Yan.Dev. All Rights Reserved.
 */
package com.yan.dev.jpa.bean;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import static javax.persistence.GenerationType.IDENTITY;

;

/**
 * Comment for User.java
 * 
 * @author <a href="mailto:yan.dev@hotmail.com">yan.dev</a>
 * 
 * @blog:<a href="http://yan-dev.iteye.com"><b>yan.dev's Blog</b></a>
 * @version 1.0
 * @time 2011-3-25 上午11:37:12
 */
@Entity
@Table(name = "yan_dev")
public class User {
	private int id;
	private String name;

	public User() {

	}

	public User(String name) {
		this.name = name;
	}

	/**
	 * @return the id
	 */
	@Id
	@GeneratedValue(strategy = IDENTITY)
	public int getId() {
		return id;
	}

	/**
	 * @param id
	 *            the id to set
	 */
	public void setId(int id) {
		this.id = id;
	}

	/**
	 * @return the name
	 */
	public String getName() {
		return name;
	}

	/**
	 * @param name
	 *            the name to set
	 */
	public void setName(String name) {
		this.name = name;
	}

}

注意：

1）import static javax.persistence.GenerationType.IDENTITY;

2）public User()

3.2

/**
 *  Copyright(c) 2010-2011 Yan.Dev. All Rights Reserved.
 */
package com.yan.dev.jpa.test;

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

import org.junit.Test;

import com.yan.dev.jpa.bean.User;

/**
 * Comment for UserTest.java
 * 
 * @author <a href="mailto:yan.dev@hotmail.com">yan.dev</a>
 * 
 * @blog:<a href="http://yan-dev.iteye.com"><b>yan.dev's Blog</b></a>
 * @version 1.0
 * @time 2011-3-25 上午11:55:44
 */
public class UserTest {
	@Test
	public void save() {
		EntityManagerFactory emf = Persistence
				.createEntityManagerFactory("FirstJPA");
		EntityManager em = emf.createEntityManager();
		EntityTransaction t = em.getTransaction();
		t.begin();
		try {
			em.persist(new User("yan_dev"));
			t.commit();
		} catch (Exception e) {
			e.printStackTrace();
			t.rollback();
		} finally {
			em.close();
			emf.close();
		}
	}
}

4. 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="FirstJPA" transaction-type="RESOURCE_LOCAL">
		<properties>
			<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" />   
			<property name="hibernate.hbm2ddl.auto" value="update" />
			<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/jpadb" />
		</properties>
	</persistence-unit>
</persistence>

注意：

persistence-unit name="FirstJPA"

property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"

property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/jpadb"

不要忘记首先创建database