JBOSS使用JPA操作数据库

1.在jboss的部署目录新增mysql-ds.xml，这个文件在jboss安装目录可以找到

<?xml version="1.0" encoding="UTF-8"?>
<datasources>
  <local-tx-datasource>
    <jndi-name>MySqlDS</jndi-name>
    <connection-url>jdbc:mysql://127.0.0.1:3306/student</connection-url>
    <driver-class>com.mysql.jdbc.Driver</driver-class>
    <user-name>root</user-name>
    <password>123456</password>
    <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</exception-sorter-class-name>
    <metadata>
       <type-mapping>mySQL</type-mapping>
    </metadata>
  </local-tx-datasource>
</datasources>

这个操作一般让程序帮我们自动建立就ok，如下所示

还有一个问题需要注意就是上面的java版本，这个一般和java_home的版本一致

到这一步我们要在eclipse里创建数据源

接下来我们选择hibernate为jpa规范，之后eclipse会为我们自动配置jpa的配置文件，配置结束后文件可能是这样的

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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_2_0.xsd">
	<persistence-unit name="TestTransaction">
	    <class>org.lxh.model.MUser</class>
		<properties>
                        <property name="hibernate.connection.username" value="root"/>
			<property name="hibernate.connection.password" value="123456"/>
			<property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/student"/>
			<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
		</properties>
	</persistence-unit>
</persistence>

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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_2_0.xsd">
	<persistence-unit name="TestTransaction">
	    <jta-data-source>java:MySqlDS</jta-data-source>
	    <class>org.lxh.model.MUser</class>
		<properties>
		 <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.JBossTransactionManagerLookup"/>  
		</properties>
	</persistence-unit>
</persistence>

3接下来在相应的包里创建实体bean就ok了

在相应包上右击，从中可以选择创建实体bean,根据提示实体Bean就能创建成功

package org.lxh.model;

import java.io.Serializable;
import javax.persistence.*;


/**
 * The persistent class for the m_user database table.
 * 
 */
@Entity
@Table(name="m_user")
@NamedQuery(name="MUser.findAll", query="SELECT m FROM MUser m")
public class MUser implements Serializable {
	private static final long serialVersionUID = 1L;

	@Id
	private int id;

	private String address;

	private String name;

	private String password;

	public MUser() {
	}

	public int getId() {
		return this.id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getAddress() {
		return this.address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public String getName() {
		return this.name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getPassword() {
		return this.password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

}

4.在EJB业务Bean里取得EntityManager

这个和依赖注入的原理基本类似，我们注入ejb可以使用@EJB注解，那么EntityManager的注入也是类似的

@PersistenceContext(unitName="TestTransaction")
	private EntityManager em;
	public void updateUser() throws Exception {
		MUser m=em.find(MUser.class, 3);
		m.setName("刘惜君XX");
		em.merge(m);
	}

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