ejb容器中的Pojo类中的EntityManager为null [英] EntityManager is null inside Pojo class in ejb container

问题描述

我有一个Java Web服务模块和一个netbeans（企业应用程序的所有部分）的ejb模块。 Web服务正在使用@EJB注入使用ejb类。
在ejb模块里面我有一个TransactionManager类，它不是一个企业bean。只是一个POJO类。我试图使用

  @PersistanceContext（unitName =testPU）注入EntityManager 
 EntityManager em; 
  

但是em是空的。
我从bean调用TransactionManager类，如果我在bean类中声明EntityManager声明，那么它在bean类中就会很好地被注入。但是在POJO中它总是为空。

我是EJB的新手（使用版本JEE7）。你能引导我吗

回复Shailendra：
我的bean和pojo在同一个jar文件中，它有bean.xml和persistence.xml。
我试图将TransactionManager类作为bean使用@Stateless和@Local，但ejb类和TransactionManager类之间有一些pojo类，当我尝试从其父pojo访问TransactionManager类时class
@EJB
TransactionManager transactionManager;
这个对象也返回null。

亲爱的Shilendra，感谢您的回复
以下是我的EJB类

 code> @Stateless 
 @Local（IMyService.class）
 public class MyService extends MyBase implements IMyService 
 {
 MyComponent component = null; 
 public void doSomething（X x）
 {
 component = new MyComponent（）; 
 component.doSomething（x）; 
} 
} 
  

我有一个POJO类作为MyComponent

  public class MyComponent extends MyBase implements IMyComponent 
 {
 TransactionManager tManager = null; 
 public void doSomething（X x）
 {
 tManager = new TransactionManager（）; 
 tManager.doSomething（x）; 
} 
} 
  

而且TransactionManager类是我想要的类Dependency注入完成PersistenceContext

  public class TransactionManager扩展MyBase实现ITransactionManager 
 {
 @PersistenceContext（unitName = TestPU）
 EntityManager em; 
 public void doSomething（X x）
 {
 em.persist（x）; 
} 
} 
  

解决方案

原因是您的POJO不受容器管理。如果您的容器支持CDI（上下文相关性注入），则在bean归档中声明您的bean（在META-INF或WEB-INF中具有beans.xml）以进行管理。

I have a Java web service module and ejb modulein netbeans (All part of an enterprise application). the web service is consuming the ejb class using @EJB injection. Inside the ejb module i have a TransactionManager class which is not an enterprise bean. just a POJO class. I am trying to inject the EntityManager using

    @PersistanceContext(unitName = "testPU")
    EntityManager em;

but the em is allways null. I am calling the TransactionManager class from by bean, and if i declare the EntityManager declaration in bean class, it injects just fine in the bean class. but in POJO it is always null.

I am new to EJB (using version JEE7) . can u please guide me ?

Reply to Shailendra : my bean and pojo are in the same jar file, and it has the bean.xml and persistence.xml. I tried to make the TransactionManager class as bean, using @Stateless and @Local, but there are some pojo classes in between the ejb class and the TransactionManager class, and when i tried to access the TransactionManager class from its parent pojo class using @EJB TransactionManager transactionManager; this object too returned null.

Dear Shilendra, thanks for the reply Below is my EJB class

    @Stateless
    @Local(IMyService.class)
    public class MyService extends MyBase implements IMyService
    {
        MyComponent component = null;
        public void doSomething(X x)
        {
             component = new MyComponent();
             component.doSomething(x);
        }
    }

I have a POJO class as MyComponent

    public class MyComponent extends MyBase implements IMyComponent
    {
        TransactionManager tManager = null;
        public void doSomething(X x)
        {
            tManager = new TransactionManager();
            tManager.doSomething(x);
        }
    }

And The TransactionManager class is the class that i want Dependency Injection done for PersistenceContext

    public class TransactionManager extends MyBase implements ITransactionManager
    {
          @PersistenceContext(unitName="TestPU")
          EntityManager em;
          public void doSomething(X x)
          {
               em.persist(x);
          }
     }

解决方案

The reason is be that your POJO is not managed by the container. If your container supports CDI (Context dependency injection) then declare your bean in a bean archive (have beans.xml in META-INF or WEB-INF) in order to be managed.

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