据我了解，我在客户端设置的 RMI 代码库将传递给服务器。然后服务器使用这个代码库来定位不在服务器类路径中的类。
只要服务器类路径中所有必需的类都可用，远程方法调用就可以正常工作。然后，我尝试从服务器类路径中删除所需的类，而是在启动 RMI 客户端时在 codebase 属性中指定所需类的新位置。不幸的是，这会给我一个 ClassNotFoundException: java.lang.ClassNotFoundException: client.Pi
堆栈跟踪：
java.rmi.ServerException: RemoteException occurred in server thread; nested exce
ption is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested excep
tion is:
java.lang.ClassNotFoundException: client.Pi
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Sou
rce)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Sour
ce)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknow
n Source)
at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
at sun.rmi.server.UnicastRef.invoke(Unknown Source)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unkn
own Source)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source)
at com.sun.proxy.$Proxy0.executeTask(Unknown Source)
at client.ComputePi.main(ComputePi.java:26)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested ex
ception is:
java.lang.ClassNotFoundException: client.Pi
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Sou
rce)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Sour
ce)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: client.Pi
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.rmi.server.LoaderHandler$Loader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at sun.rmi.server.LoaderHandler.loadClassForName(Unknown Source)
at sun.rmi.server.LoaderHandler.loadClass(Unknown Source)
at sun.rmi.server.LoaderHandler.loadClass(Unknown Source)
at java.rmi.server.RMIClassLoader$2.loadClass(Unknown Source)
at java.rmi.server.RMIClassLoader.loadClass(Unknown Source)
at sun.rmi.server.MarshalInputStream.resolveClass(Unknown Source)
at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source)
at java.io.ObjectInputStream.readClassDesc(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at sun.rmi.server.UnicastRef.unmarshalValue(Unknown Source)
... 11 more
启动服务器：
C:\TEMP\RMI\RMIDemo\src>java
-cp C:\Users\samue_000\public_html\classes\compute.jar;C:\TEMP\RMI\RMIDemo\src
-Djava.security.policy=server.policy
-Djava.rmi.server.useCodebaseOnly=false
engine.ComputeEngine
>> ComputeEngine bound启动客户端：
C:\TEMP\RMI\RMIDemo\src>java
-cp C:\Users\samue_000\public_html\classes\compute.jar;c:\Temp\RMI\RMIDemo\src;c:\temp
-Djava.security.policy=client.policy
-Djava.rmi.server.codebase=file:/C:/Users/samue_000/public_html/classes
client.ComputePi在客户端的类路径 (c:\temp) 中包含客户端也需要的所需的 client.Pi 类。为了告诉服务器这个类所在的位置，我将一个副本放在一个单独的文件夹中，并使用 codebase 属性指定了这个文件夹。该类的确切位置是 C:/Users/samue_000/public_html/classes/client/Pi.class。它都在同一台物理机器上运行（没有虚拟机）。所以我不明白为什么服务器没有从客户端获取代码库并加载所需的 client.Pi 类。
我试图将发布的信息最小化到所需的部分，以免过度填充这篇文章。如果需要更多信息来帮助我解决此问题，请告诉我。这让我快疯了。我在这个问题上工作了几个小时和几天......
编辑：我使用了与oracle的这篇文章中描述的几乎相同的代码。唯一的区别是我以编程方式创建 rmi 注册表，而不是单独启动注册表。所以代码本身应该没有任何问题。只要 Pi 类位于服务器的类路径中，它就可以正常工作。但是一旦 Pi 类只存在于代码库和客户端的类路径中，它就不再起作用了。