EJB6: EntityBean例子

      本例子描述向EJB容器（JBoss）部署http://kylinsoong.iteye.com/blog/824676中描述的例子的全过程，链接博客中描述的例子包含7个实体：User、Event、Friend、Property、Pet、UserCard、Wife，其中：User和Event，User和Friend，Event和Property，Wife和Pet，Pet和Property关系为一对多关系；而User和UserCard，Friend和UserCard，Wife和UserCard，User和Wife之间的关系是一对一关系；

下面开始部署http://kylinsoong.iteye.com/blog/824676中描述的例子：

 

1 JBoss数据源的配置

      数据源的备份文件可以在JBOSS_Home\docs\examples\jca下找到，我用的是Oracle10g所以我用到的JBoss数据源的配置JBOSS_Home\docs\examples\jca下的oracle-ds.xml，将oracle-ds.xml做一下修改，修改完拷贝到JBOSS_Home\server\production\deploy下，修改完的oracle-ds.xml的内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<datasources>
  <local-tx-datasource>
    <jndi-name>OracleDS</jndi-name>
    <connection-url>jdbc:oracle:thin:@192.168.68.120:1521:orcl</connection-url>
    <driver-class>oracle.jdbc.driver.OracleDriver</driver-class>
    <user-name>***</user-name>
    <password>***</password>
    <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.OracleExceptionSorter</exception-sorter-class-name>
      <metadata>
         <type-mapping>Oracle10g</type-mapping>
      </metadata>
  </local-tx-datasource>
</datasources>

 其中说明了JBoss数据源的jndi-name：OracleDS，jndi-name必须唯一；

                                         连接URL：jdbc:oracle:thin:@192.168.68.120:1521:orcl

                                   连接驱动名称：oracle.jdbc.driver.OracleDriver

以及数据库名称及密码，数据库类型；

拷贝完成后启动JBoss，http://localhost:8080/jmx-console/HtmlAdaptor?action=displayMBeans下jboss.jca可以看到刚才添加数据源的配置信息：

 

2 Bean开发

首先修改之前POJO实体，让其手实现java.io.Serializable接口，

其次用一个无状态Session Bean来控制Entity Bean

贴出Remote接口UserService和无状态SessionBean：UserServiceBean

public interface UserService {

	public void insertUser(User user);
	public void updateName(String newname, Long id);
	public void mergeUser(User user);
	public void deleteUser(Long id);
	public User getUserByID(Long id);
	public List<User> getUserList();
}

 

@Stateless
@Remote(UserService.class)
public class UserServiceBean implements UserService {

	@PersistenceContext(unitName="com.tibco.hibernate.po") 
	protected EntityManager em;
	
	public void insertUser(User user) {
		em.persist(user);
	}

	public void updateName(String name, Long id) {
		User user = em.find(User.class, id);
		if(user != null){
			user.setName(name);
		}
	}

	public void mergeUser(User user) {
		em.merge(user);
	}

	public void deleteUser(Long id) {
		User user = em.find(User.class, id);
		if(user != null){
			em.remove(user);
		}
	}

	public User getUserByID(Long id) {
		return em.find(User.class, id);
	}

	public List<User> getUserList() {
		Query query = em.createQuery("select u from User as u");
		return query.getResultList();
	}

}

      如上：Remote接口UserService提供了一套对User的增删改查方法，无状态SessionBean类UserServiceBean分别提供了这些方法的一个实现。

@PersistenceContext(unitName="com.tibco.hibernate.po") 指定了Persistence unit的名字，容器通过这个名字可以找到相应的实体类和数据源等

 

3. persistence.xml编写

      我们知道Persistence unit 是在persistence.xml中定义的，实体类型之所以能被EntityManager控制是因为提供了Persistence unit，根据持久化规范的要求，该描述文件是必须提供的，如果不提供这一文件，则Persistence unit也
 将不存在，因此应用也不能够获得和使用EntityManager，下面是persistence.xml内容：

<?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="com.tibco.hibernate.po">
    <jta-data-source>java:/OracleDS</jta-data-source>
    <properties>
     <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
     <!-- 调整JDBC抓取数量的大小: Statement.setFetchSize() -->
     <property name="hibernate.jdbc.fetch_size" value="18"/>
     <!-- 调整JDBC批量更新数量 -->
     <property name="hibernate.jdbc.batch_size" value="10"/>
     <!-- 显示最终执行的SQL -->
     <property name="hibernate.show_sql" value="true"/>
     <!-- 格式化显示的SQL -->
     <property name="hibernate.format_sql" value="true"/>
    </properties>
  </persistence-unit>
</persistence>

 配置文件说明我们用的JPA的实现是Hibernate，“hibernate.hbm2ddl.auto”值得容器启动时创建表，容器关闭时删除表，"hibernate.show_sql"在容器Console口打印SQL语句，"hibernate.format_sql"说明在容器Console显示的SQL语句是格式化的；

 

4 将过程打包部署到JBOSS_Home\server\production\deploy下

我们用Ant实现，关于Ant参考http://kylinsoong.iteye.com/admin/blogs/787097这里直接给出build.xml

<?xml version="1.0"?>
<project name="com.tibco.hibernate" default="deploy" basedir="..">

	<property environment="env" />
	<property name="app.dir" value="${basedir}\com.tibco.hibernate" />
	<property name="src.dir" value="${app.dir}\src" />
	<property name="jboss.home" value="${env.JBOSS_HOME}" />
	<property name="jboss.server.config" value="production" />
	<property name="build.dir" value="${app.dir}\build" />
	<property name="build.classes.dir" value="${build.dir}\classes" />

	<!-- Build classpath -->
	<path id="build.classpath">
		<fileset dir="${jboss.home}\client">
			<include name="*.jar" />
		</fileset>
		<fileset dir="${jboss.home}\client\userService">
			<include name="*.jar" />
		</fileset>
		<pathelement location="${build.classes.dir}" />
	</path>
	
	<target name="prepare" depends="clean">
		<mkdir dir="${build.dir}" />
		<mkdir dir="${build.classes.dir}" />
	</target>

	<target name="compile" depends="prepare" description="compile">
		<javac srcdir="${src.dir}" destdir="${build.classes.dir}" debug="on" deprecation="on" optimize="off" includes="com/**">
			<classpath refid="build.classpath" />
		</javac>
	</target>

	<target name="ejbjar" depends="compile" description="ejbjar">
		<jar jarfile="${app.dir}\UserBean.jar">
			<fileset dir="${build.classes.dir}">
				<include name="com/tibco/hibernate/po/*.class" />
				<include name="com/tibco/hibernate/po/bean/*.class" />
			</fileset>
			<metainf dir="${src.dir}\META-INF">
				<include name="persistence.xml" />
			</metainf>
		</jar>
	</target>

	<target name="deploy" depends="ejbjar">
		<copy file="${app.dir}\UserBean.jar" todir="${jboss.home}\server\${jboss.server.config}\deploy" />
	</target>

	<!-- =================================================================== -->
	<!-- Cleans up generated stuff                                           -->
	<!-- =================================================================== -->
	<target name="clean">
		<delete dir="${build.dir}" />
		<delete file="${jboss.home}\server\${jboss.server.config}\deploy\UserBean.jar" />
	</target>

</project>

 运行Ant，文件部署成功

 

5 测试

运行这段代码可以插入一条数据并查询：

public static void main(String[] args) throws NamingException {
		Properties properties = new Properties();
		properties.setProperty(Context.INITIAL_CONTEXT_FACTORY , "org.jnp.interfaces.NamingContextFactory");
        properties.setProperty(Context.PROVIDER_URL, "jnp://localhost");
        Context ctx = new InitialContext(properties);
        UserService userService = (UserService) ctx.lookup("UserServiceBean/remote");
        
		User user = JPAClient.getUser();
		userService.insertUser(user);
        
        for(User u : userService.getUserList()) {
        	System.out.println("id:" + u.getId() + " name:" + u.getName());
        }
	}

 

当然我们也可以运用反射修改刚才插入的user：

public static void main(String[] args) throws NamingException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
		Properties properties = new Properties();
		properties.setProperty(Context.INITIAL_CONTEXT_FACTORY , "org.jnp.interfaces.NamingContextFactory");
        properties.setProperty(Context.PROVIDER_URL, "jnp://localhost");
        Context ctx = new InitialContext(properties);
        Object obj = ctx.lookup("UserServiceBean/remote");
        for(Method m : obj.getClass().getMethods()) {
        	if(m.getName().compareTo("updateName") == 0){
        		m.invoke(obj, new Object[]{"Kobe Bryant", new Long(1)});
        	}
        }
        for(Method m : obj.getClass().getMethods()) {
        	if(m.getName().compareTo("getUserByID") == 0) {
        		User user = (User) m.invoke(obj, new Object[]{new Long(1)});
        		System.out.println(user.getName());
        	}
        }

	}