客户端中的@EJB 注释 [英] @EJB annotation in clients

问题描述

使用 NetBeans，我在包含 main() 的类中执行以下操作，并且它有效:

Using NetBeans, I do the following in the class containing main(), and it works:

import javax.ejb.EJB;

public class Master {
    @EJB
    TestBeanARemote x;

    public static void main(String[] args) {
        Master m = new Master();
        m.doStuff();
    }
//doStuff includes x, but it works, so who cares.
...

但是，如果我在被调用的类中执行此操作，则会失败.似乎被调用的类要求我避免使用注释，而是使用整个 InitialContext() 设置.

If I do that in a called class, however, it fails. It seems that a called class requires me to avoid using annotations and instead use a the whole InitialContext() setup.

String testRun(String arg) {
   InitialContext ic;
    try {
        ic = new InitialContext();
        x = (TestBeanARemote) ic.lookup("com.bnncpa.testing.TestBeanARemote");
        return x.testRun(arg);

    }

完整的失败副本如下:

package enterpriseapplication1;
public class Main {

    private Secondary x = new Secondary();

    public static void main(String[] args) {
        Main m = new Main();
        m.doStuff();
    }

    public void doStuff() {
        System.out.println(x.testRun("bar"));
    }

}

package enterpriseapplication1;
import org.mine.testing.TestBeanARemote;
import javax.ejb.EJB;

public class Secondary {
   @EJB
   static private TestBeanARemote x;

   String testRun(String arg) {
       return x.testRun(arg);
   }
}

为什么 @EJB 不能在包的所有类中工作，是否有特殊原因?我希望能够在我使用的任何地方简单地标记 @EJB.

Is there a particular reason why @EJB might not work in all classes of a package? I'd like to be able to simply tag @EJB wherever I'm using one.

是否有更好的方法来解决我完全遗漏的问题?

Is there some better way to go about this that I'm missing entirely?

为了解决使用 appclient 的问题，这是我的堆栈跟踪:

To address the concern over using an appclient, here's my stack trace:

May 11, 2009 4:24:46 PM com.sun.enterprise.appclient.MainWithModuleSupport <init>
WARNING: ACC003: Application threw an exception.
java.lang.NullPointerException
    at enterpriseapplication1.Secondary.testRun(Secondary.java:20)
    at enterpriseapplication1.Main.doStuff(Main.java:27)
    at enterpriseapplication1.Main.main(Main.java:23)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.sun.enterprise.util.Utility.invokeApplicationMain(Utility.java:266)
    at com.sun.enterprise.appclient.MainWithModuleSupport.<init>(MainWithModuleSupport.java:449)
    at com.sun.enterprise.appclient.MainWithModuleSupport.<init>(MainWithModuleSupport.java:259)
    at com.sun.enterprise.appclient.Main.main(Main.java:200)
Exception in thread "main" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at com.sun.enterprise.appclient.MainWithModuleSupport.<init>(MainWithModuleSupport.java:461)
    at com.sun.enterprise.appclient.MainWithModuleSupport.<init>(MainWithModuleSupport.java:259)
    at com.sun.enterprise.appclient.Main.main(Main.java:200)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.sun.enterprise.util.Utility.invokeApplicationMain(Utility.java:266)
    at com.sun.enterprise.appclient.MainWithModuleSupport.<init>(MainWithModuleSupport.java:449)
    ... 2 more
Caused by: java.lang.NullPointerException
    at enterpriseapplication1.Secondary.testRun(Secondary.java:20)
    at enterpriseapplication1.Main.doStuff(Main.java:27)
    at enterpriseapplication1.Main.main(Main.java:23)
    ... 8 more
Java Result: 1

推荐答案

问题是@EJB 只会被注入到托管"类中.

The problem is that @EJB will only be injected in to "managed" classes.

在 Java EE 中，托管类非常少.特别是应用程序客户端(在本例中是您的主要")、EJB(无状态和有状态 EJB、消息 Bean 等)和 Servlet.

In Java EE there are very few managed classes. Notably Application Clients (your "main" here in this case), EJBs (Stateless and Stateful EJBs, Message Beans, etc.), and Servlets.

其他任何东西(即泛型类、JPA 实体等)都不会注入资源，您将需要依靠查找机制来访问您的资源.

Anything else (i.e. generic classes, JPA entities, etc.) will not have the resources injected, and you will need to rely on the lookup mechanism to get access to your resources.

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