java EJB 容器中可能的 JNDI 查找
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Possible JNDI lookups within EJB container
提问by Steven
I'm going through the EJB 3.1 specand am trying to grasp the different possible ways a JNDI call can be made.
我正在阅读EJB 3.1 规范，并试图掌握进行 JNDI 调用的不同可能方式。
You can do it using a SessionContextand an InitialContext(or a self-created context based on the Initial- or SessionContext). Based on which you use the syntax differs, but I can't seem to find the logic behind it.
您可以使用SessionContext和InitialContext（或基于 Initial- 或 SessionContext 的自创建上下文）来实现。根据您使用的语法而有所不同，但我似乎无法找到其背后的逻辑。
So my question is: when can I use what syntax to use JNDI calls within an EJB container environment?
所以我的问题是：我什么时候可以使用什么语法在 EJB 容器环境中使用 JNDI 调用？
The rest of this question just serves as illustration of my point.
这个问题的其余部分只是为了说明我的观点。
For example, I believe this is always possible for a correctly injected sessioncontextor created initialcontext:
例如，我相信这对于正确注入sessioncontext或创建始终是可能的initialcontext：
ctx.lookup(java:global[/<app-name>]/<module-name>/<bean-name>[!<fully-qualified-interface-name>])
ctx.lookup(java:comp/env ...)
// special ones like these
ctx.lookup("java:comp/UserTransaction");
ctx.lookup("java:comp/ORB");
Sometimes (only for session context?) this shorter version is possible:
有时（仅用于会话上下文？）这个较短的版本是可能的：
ctx.lookup(<bean-name>);
What about in an embedded environment, can only globalreferences be used?
在 a 中呢embedded environment，只能使用global引用吗？
回答by Mitja Gomboc
I usually inject EJBs inside EJB container with @EJB annotation. So the JDNI look ups are done by the server at deploy time.
我通常使用@EJB 注释将 EJB 注入到 EJB 容器中。因此 JDNI 查找由服务器在部署时完成。
For example JBOSS deployment:
例如 JBOSS 部署：
INFO [org.jboss.as.ejb3.deployment.processors.EjbJndiBindingsDeploymentUnitProcessor] (MSC service thread 1-2) JNDI bindings for session bean named TestBean in deployment unit subdeployment "MyEJB.jar" of deployment "MyProject.ear" are as follows:
INFO [org.jboss.as.ejb3.deployment.processors.EjbJndiBindingsDeploymentUnitProcessor]（MSC服务线程1-2）部署“MyProject.ear”的部署单元子部署“MyEJB.jar”中名为TestBean的会话bean的JNDI绑定如下：
java:global/MyProject/MyEJB/TestBean!my.project.TestBean
java:app/MyEJB/TestEJB!my.project.TestBean
java:module/TestEJB!my.project.TestBean
java:global/MyProject/MyEJB/TestEJB
java:app/MyEJB/TestBean
java:module/TestBean
Some are per EJB specification some are application server dependent.
有些是根据 EJB 规范的，有些是依赖于应用程序服务器的。
If you have to make look ups from context I think the best way is to use java:global.
如果您必须从上下文中查找，我认为最好的方法是使用java:global。
You can also find some additional info at: http://glassfish.java.net/javaee5/ejb/EJB_FAQ.html#POJOLocalEJB
您还可以在以下位置找到一些其他信息：http: //glassfish.java.net/javaee5/ejb/EJB_FAQ.html#POJOLocalEJB
回答by Mike Braun
jndi is a bit like a file system. You can refer to things using a relative path based on where you are in the tree (where you "cd"-ed to).
jndi 有点像文件系统。您可以使用基于您在树中的位置（“cd”-ed 到的位置）的相对路径来引用事物。
The injected session context is by default "positioned" on java:comp, so there you reference things that are available in java:comp, without the need to provide the "full path".
注入的会话上下文默认“定位”在 java:comp 上，因此您可以在那里引用 java:comp 中可用的内容，而无需提供“完整路径”。
Note that java:comp itself is relative to a single EJB bean, or because of historical reasons to the entire Web module.
请注意，java:comp 本身是相对于单个 EJB bean 而言的，或者由于历史原因与整个 Web 模块相关。
I'm not 100% sure what you mean with embedded environment, but if the code from which you are doing the JNDI lookup is not part of any of the predefined scopes (like java:module, java:app, etc) only java:global can be portably used.
我不是 100% 确定您对嵌入式环境的意思，但是如果您进行 JNDI 查找的代码不是任何预定义范围（如 java:module、java:app 等）的一部分，则只有 java： global 可以便携使用。
