public inerface HelloWold extends EJBLocalObject{
    Public String getResult();
}
						

public class HelloWorldEntityBean 
         implements HelloWold, EntityBean{
    private int id;
    private String result;
    private EntityContext txt;
   
    public HelloWorldEntityBean(){}
    public void setEntityContext( EntityContext text ){ 
        txt = text;
    }
   
    public String getResult(){ 
        Return result; 
    }
        
    public int getId(){
        return id; 
    }
    
    public void setResult( String result ){ 
        this.result = result;
    }
    
    public String cretaeByName( String name ) throws EJBException{
        .....
    }
   
 }						
						

@Entity
@Table(name=”hellotable”)
public class HelloWoldEntity{   
    @Id
    private int id; p
    private String result; 
    
    public HelloWoldEntity(){} 
    
    public String getResult(){ 
        return result;
    }
    
    public int getId(){
        return id;
    }  
    
    public void setResult( String result ){ 
        this.result = result;
    }
}						
						

<one-to-one        
    name="address"        
    class="com.foo.Address"        
    cascade="All"        
    lazy="false"/>

public class Order{     
	@OneToOne(cascade=CascadeType.ALL,fetch=FetchType.LAZYL)    
	Address address;
    ......	
}
						

public class Order{    
    Address address;
    ......   
}

• 減少了配置檔案的數量，特別是在實體(Entity)比較多的系統中，維護大量的O/R Mapping xml配置檔案是不少的工作量。
• 減少了配置需要標註的內容。由於annotation由java compiler來編譯解析，很多需要在xml配置中顯式宣告的內容不再需要（比如變數名稱，型別，集合中的物件型別等）。
• Annotation的編譯期檢查可以避免xml檔案中容易出現的配置語法錯誤，在IDE中及時發現和糾正。
• 無需在xml配置檔案和java程式碼中切換，較少思維的跳躍，提高了開發效率。
• annotation被編譯到java bytecode中，省略了xml的解析過程，極大的提升應用的啟動速度和記憶體佔用（特別是Entity多的情況）。

public interface EntityManager {
    public void persist(Object entity);
    public  T merge(T entity);
    public void remove(Object entity);
    public  T find(Class entityClass, Object primaryKey);
    public  T getReference(Class entityClass, Object primaryKey);
    public void flush();
    public void setFlushMode(FlushModeType flushMode);
    public FlushModeType getFlushMode();
    public void lock(Object entity, LockModeType lockMode);
    public void refresh(Object entity);
    public void clear();
    public boolean contains(Object entity);
    public Query createQuery(String ejbqlString);
    public Query createNamedQuery(String name);
    public Query createNativeQuery(String sqlString);
    public Query createNativeQuery(String sqlString, Class result-
    Class);
    public Query createNativeQuery(String sqlString, String result-
    SetMapping);
    public void close();
    public boolean isOpen();
    public EntityTransaction getTransaction();
}
				
				

<entity-manager>
    <name>myEntityManager>/name>
    <provider>com.redsoft.ejb3.PersistenceProviderImpl>/provider>
    <class>com.redsoft.samples.HelloEntityBean>/class>
    <properties>
        <property name="ConnectionDriverName" value="com.mysql.jdbc.Driver"/>
        <property name="ConnectionURL" value="jdbc:mysql://localhost/EJB3Test"/>
        <property name="ConnectionUserName" value="ejb3"/>
        <property name="ConnectionPassword" value="ejb3"/>
   >/properties>
</entity-manager>

}
				
				

public class HelloWorld {

    public static void main( final String[] args ){

        /*
         * Obtain an EJB3 entity manager
         */
        final EntityManagerFactory emf = Persistence.createEntityManagerFactory();
        final EntityManager entityManager = emf.createEntityManager();

        // Construct a HelloEntityBean
        final HelloEntityBean hello = new HelloEntityBean( 1, "foo" );
        EntityTransaction trans = entityManager.getTransaction();
        trans.begin();
        entityManager.persist( hello );
        trans.commit();
        System.out.println( "Successfully persist hello: " + hello );

        // Look up the HelloEntityBean by primarky key
        final HelloEntityBean anotherHello = entityManager.find( HelloEntityBean.class, new Integer( hello.getId() ) );
        System.out.println( "Found hello: " + anotherHello );

        // close the EntityManager
        entityManager.close();
        emf.close();
    }
}
				

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "file://spring-beans.dtd">

<beans>
	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
		<property name="driverClassName"><value>com.mysql.jdbc.Driver</value></property>
		<property name="url"><value>jdbc:mysql://localhost/EJB3Test</value></property>
		<property name="username"><value>ejb3</value></property>
		<property name="password"><value>ejb3</value></property>
	</bean>
	<bean id="entityManagerFactory"
		class="org.springframework.orm.ejb3.LocalEntityManagerFactoryBean">
		<property name="persistenceInfo"><ref local="persistenceInfo"/></property>
		
	</bean>
	<bean id="persistenceInfo" class="com.redsoft.ejb3.PersistenceInfoImpl">
		<property name="nonJtaDataSource"><ref local="dataSource"/></property>
		<property name="entityManagerName"><value>myEntityManager</value></property>
		<property name="persistenceProviderClassName">
			<value>
				com.redsoft.ejb3.PersistenceProviderImpl
			</value>
		</property>
		<property name="entityClassNames">
		<list>
			<value>com.redsoft.ejb3.spring.Child</value>
			<value>com.redsoft.ejb3.spring.Father</value>
		</list>
		</property>
		<property name="properties">
			<props>
			<prop key="javax.jdo.PersistenceManagerFactoryClass">
				com.redsoft.jdo.PersistenceManagerFactoryImpl
			</prop>
			</props>
		</property>
	</bean>
	<bean id="transactionManager" class="org.springframework.orm.ejb3.EJB3TransactionManager"
		singleton="true">
		<property name="entityManagerFactory">
			<ref local="entityManagerFactory" />
		</property>
	</bean>
	
	<bean id="dao"
		class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean"
		singleton="true">
		<property name="transactionManager">
			<ref local="transactionManager" />
		</property>
		<property name="target">
			<bean class="com.redsoft.ejb3.spring.DAOImpl">
				<property name="entityManagerFactory">
					<ref local="entityManagerFactory" />
				</property>
			</bean>
		</property>
		<property name="transactionAttributes">
			<props>
				<prop key="save*">PROPAGATION_REQUIRED</prop>
				<prop key="remove*">PROPAGATION_REQUIRED</prop>
				<prop key="del*">PROPAGATION_REQUIRED</prop>
				<prop key="update*">PROPAGATION_REQUIRED</prop>
				<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
				<prop key="find*">PROPAGATION_REQUIRED,readOnly</prop>
				<prop key="query*">PROPAGATION_REQUIRED,readOnly</prop>
			</props>
		</property>
	</bean>
</beans>