EJB之JPA模块（一）

EJB中的JPA是对对象持久化操作的，jboss中默认的实现是通过hibernate实现。一下是关于jpa的一个小例子。
1. 将%JBOSS_HOME%\docs\examples\jca\mysql-ds.xml复制到%JBOSS_HOME%\server\default\deploy目录下，修改数据源配置：

<?xml version="1.0" encoding="UTF-8"?>

<!-- $Id: mysql-ds.xml 71535 2008-04-01 07:05:03Z [e-mail] $ -->
<!--  Datasource config for MySQL using 3.0.9 available from:
http://www.mysql.com/downloads/api-jdbc-stable.html
-->

<datasources>
  <local-tx-datasource>
    <jndi-name>MySqlDS</jndi-name>
    <connection-url>jdbc:mysql://localhost:3306/ejb3</connection-url>
    <driver-class>com.mysql.jdbc.Driver</driver-class>
    <user-name>root</user-name>
    <password>root</password>
    <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</exception-sorter-class-name>
    <!-- should only be used on drivers after 3.22.1 with "ping" support
    <valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLValidConnectionChecker</valid-connection-checker-class-name>
    -->
    <!-- sql to call when connection is created
    <new-connection-sql>some arbitrary sql</new-connection-sql>
      -->
    <!-- sql to call on an existing pooled connection when it is obtained from pool - MySQLValidConnectionChecker is preferred for newer drivers
    <check-valid-connection-sql>some arbitrary sql</check-valid-connection-sql>
      -->

    <!-- corresponding type-mapping in the standardjbosscmp-jdbc.xml (optional) -->
    <metadata>
       <type-mapping>mySQL</type-mapping>
    </metadata>
  </local-tx-datasource>
</datasources>

2. 配置persistence.xml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:shemaLocation="http://java.sun.com/xml/ns/persistence
	http://java.sun.com/xml/ns/persistence/presistence_1_0.xsd" version="1.0">
	
	<persistence-unit name="test" transaction-type="JTA">
		<jta-data-source>java:/MySqlDS</jta-data-source>
		<properties>
			<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
			<property name="hibernate.hbm2ddl.auto" value="update"/>
			<property name="show_sql">true</property>
		</properties>
	</persistence-unit>
</persistence>

3.编写EJB Session Bean并发布

package com.kevin.jpa;

import javax.ejb.Remote;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

@Stateless
@Remote
public class PersonManagerBean implements PersonManager {

	// 当persistence.xml中只有一个persistence-unit时，unitName可省略
	@PersistenceContext(unitName = "test")
	private EntityManager em;
	
	public void addPerson(String name) {
		Person person = new Person();
		person.setId(10);
		person.setName(name);
		em.persist(person);
	}

}