JPA小例

  ：
package com.dada.entity;

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

@Entity
public class UserBean {
	private Integer id;
	private String name;
	public UserBean() {
		super();
		// TODO Auto-generated constructor stub
	}
	@Id
	@GeneratedValue
	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;
	}
	
}

   ：
package com.dada.test;

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

import com.dada.entity.UserBean;

public class Testgg {
	private EntityManager em;
	private EntityManagerFactory emf;
	public Testgg() {
		super();
		emf = Persistence.createEntityManagerFactory("testJPAPU");
		em = emf.createEntityManager();
	}
	
	public void add(UserBean bean) {
		em.getTransaction().begin();
		em.persist(bean);
		em.getTransaction().commit();
	}
	
	public static void main(String[] args) {
		UserBean ub = new UserBean();
		ub.setName("dada");
		UserBean ub1 = new UserBean();
		ub1.setName("   ");
		new Testgg().add(ub);
		new Testgg().add(ub1);
	}
}

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="testJPAPU" transaction-type="RESOURCE_LOCAL">
		<provider>org.hibernate.ejb.HibernatePersistence</provider>
		<class>com.dada.entity.UserBean</class>
		<properties>
			<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
			<property name="hibernate.connection.url"
				value="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8" />
			<property name="hibernate.connection.username" value="root" />
			<property name="hibernate.connection.password" value="test" />
			<property name="hibernate.show_sql" value="true" />
			<property name="hibernate.format_sql" value="true" />
		</properties>
	</persistence-unit>

</persistence>