eclipse 在（引用）Web 项目中找不到引用的 EJB 项目的类

Classes of referenced EJB project not found in (the referencing) Web project

提问by ars-longa-vita-brevis

I'm learning J2EE and EJB and I've run into a strange problem. This is my project setup:

我正在学习 J2EE 和 EJB，但遇到了一个奇怪的问题。这是我的项目设置：

I'm using Glassfish 3.1 and Eclipse 3.7. I have two projects in Eclipse:

我使用的是 Glassfish 3.1 和 Eclipse 3.7。我在 Eclipse 中有两个项目：

1. An EJB 3.0 compliant project, myEjbProject
2. A Dynamic Web Project, myWebProject

1. 一个符合 EJB 3.0 的项目， myEjbProject
2. 一个动态的网络项目， myWebProject

I'm injecting an EJB session bean mySessionBeanPackage.mySessionBeanfrom myEjbProjectinto a servlet myServletPackage.myServletin myWebProjectand then (in the servlet) calling a simple method defined in the session bean.

我注入一个EJB会话beanmySessionBeanPackage.mySessionBean从myEjbProject成servletmyServletPackage.myServlet中myWebProject，然后（在servlet）调用会话bean定义的简单方法。

I've provided myWebProjectwith a reference to myEjbProject(using the Properties -> Project References dialog). However, for some reason, the server is unableto find the session bean. The exact error I get is:

我已经提供myWebProject了一个参考myEjbProject（使用“属性”->“项目引用”对话框）。但是，由于某种原因，服务器无法找到会话 bean。我得到的确切错误是：

SEVERE: Class [ LmySessionBeanPackage/mySessionBean ] not found. Error while loading [ class myServletPackage.myServlet ]

严重：找不到类 [ LmySessionBeanPackage/mySessionBean ]。加载 [ class myServletPackage.myServlet ] 时出错

Note that boththe EJB project and the web project have been published to the server and I've double-checked that the class file generated for the bean is, in fact, present on the server (so I can't think of a reason why the server isn't able to find them).

请注意，这两个EJB项目和Web项目已发布到服务器，我已经反复检查为bean生成的类文件，其实存在于服务器上（所以我不能想出一个理由为什么服务器无法找到它们）。

Can anyone tell me what I'm doing wrong?

谁能告诉我我做错了什么？

I've also tried

我也试过

• adding the classes folder of myEjbProjectexplicitly to the Java Build Path -> Libraries list of myWebProject. This is in addition to the project reference (although I think adding a project reference should have sufficed in the first place). Anyway, it makes no difference (same error message as before).

• creating a JAR file from myEjbProjectusing the Export -> EJB Jar File option (I don't want to get into writing an Ant script at the moment). I then put this JAR in the Java Build Path -> Libraries section of myWebProject. This approach does not solve the problem either (same error message as before).

• modifying the session bean to have

  • no interface
  • a local interface
  • a remote interface

  and modifying the injection accordingly. E.g., for a bean with only a local interface, I used:

  @EJB mySessionBeanPackage.mySessionBeanLocal myBean

  This approach did not solve the problem either (same error message as before).

• doing away with myEjbProjectaltogether and adding the session bean to myWebProjectas myServletPackage.mySessionBean(same package as the servlet). In this case, I can inject the session bean successfully into the servlet using

  @EJB mySessionBeanPackage.mySessionBean myBean

• doing away with myEjbProjectaltogether and adding the session bean to myWebProjectas mySessionBeanPackage.mySessionBean(a new package). In this case also, I can inject the session bean successfully into the servlet using

  @EJB mySessionBeanPackage.mySessionBean myBean

• 将 的类文件夹myEjbProject显式添加到 Java 构建路径 -> myWebProject. 这是对项目参考的补充（尽管我认为首先添加项目参考应该就足够了）。无论如何，它没有区别（与以前相同的错误消息）。

• myEjbProject使用“导出”->“EJB Jar 文件”选项创建 JAR 文件（我目前不想编写 Ant 脚本）。然后我将这个 JAR 放在 .java 的 Java 构建路径 -> 库部分myWebProject。这种方法也不能解决问题（与以前相同的错误消息）。

• 修改会话 bean 以具有

  • 没有界面
  • 本地接口
  • 远程接口

  并相应地修改注入。例如，对于只有本地接口的 bean，我使用了：

  @EJB mySessionBeanPackage.mySessionBeanLocal myBean

  这种方法也没有解决问题（与以前相同的错误消息）。

• 废除myEjbProject共以及将所述会话beanmyWebProject作为myServletPackage.mySessionBean（相同的包作为servlet）。在这种情况下，我可以使用以下命令将会话 bean 成功注入到 servlet 中

  @EJB mySessionBeanPackage.mySessionBean myBean

• 废除myEjbProject干脆加入会话beanmyWebProject作为mySessionBeanPackage.mySessionBean（新包装）。在这种情况下，我也可以使用以下方法将会话 bean 成功注入到 servlet 中

  @EJB mySessionBeanPackage.mySessionBean myBean

回答by Ross

I would recommend taking a look at the actual EAR that Eclipse packages and deploys to the server. You can do this by exporting the EAR project (right click on EAR project -> export -> Java EE -> EAR file)

我建议查看 Eclipse 打包并部署到服务器的实际 EAR。您可以通过导出 EAR 项目来完成此操作（右键单击 EAR 项目 -> 导出 -> Java EE -> EAR 文件）

I think the step you are missing is to add the EJB project to the WEB project's MANIFEST file. But just in case you are missing a few more steps I would check the following:

我认为您缺少的步骤是将 EJB 项目添加到 WEB 项目的 MANIFEST 文件中。但以防万一你错过了更多的步骤，我会检查以下内容：

1. EJB and WEB projects are modules of the EAR project. Right click the EAR project -> properties -> Deployment Assembly -> Add -> Project -> select the EJB and the WEB project. If you export your EAR project now you will notice that the EJB and the WEB project is packaged with the EAR.
2. Add EJB project to MANIFEST of WEB project. Right click the WEB project -> properties -> Deployment Assembly -> Manifest entries -> Add -> select the EJB project. You can open the MANIFEST.MF file and see that it now includes the EJB project.

1. EJB 和WEB 项目是EAR 项目的模块。右键单击EAR 项目-> 属性-> 部署程序集-> 添加-> 项目-> 选择EJB 和WEB 项目。如果您现在导出 EAR 项目，您会注意到 EJB 和 WEB 项目与 EAR 一起打包。
2. 将 EJB 项目添加到 WEB 项目的 MANIFEST。右键单击WEB项目->属性->部署程序集->清单条目->添加->选择EJB项目。您可以打开 MANIFEST.MF 文件并看到它现在包含 EJB 项目。

Also I like adding the EJB project to the WEB project build path just so that it is included in the WEB's classpath: Right click WEB project -> properties -> Java Build Path -> Projects -> Add -> Select the EJB.

另外，我喜欢将 EJB 项目添加到 WEB 项目构建路径中，以便将其包含在 WEB 的类路径中：右键单击 WEB 项目 -> 属性 -> Java 构建路径 -> 项目 -> 添加 -> 选择 EJB。