绑定 RMI 服务时抛出 ServerException

Question

我正在尝试构建简单的回显服务器作为 RMI 应用程序（按照 Sun 教程中所述逐步进行）。

所有源代码如下所示，非常简单：

package test;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface EchoServer extends Remote {
    public String sendString (String str) throws RemoteException;        
}

---

package test;

import java.rmi.server.UnicastRemoteObject;
import java.rmi.RemoteException;

public class EchoServerImpl extends UnicastRemoteObject implements EchoServer {

    public EchoServerImpl () throws RemoteException {
        super ();
    }

    public String sendString (String str) throws RemoteException {
        return str.toUpperCase();
    }
}

---

package test;

import java.rmi.Naming;

public class RMIServer {

    public RMIServer () {
        try {
            EchoServer eServer = new EchoServerImpl ();
            Naming.rebind ("rmi://localhost:1099/EchoService", eServer); // <--exception
        } catch (Exception e) {
            e.printStackTrace ();
        }
    }

    public static void main(String[] args) {
        new RMIServer ();
    }
}

我用 rmic 编译代码，然后看到文件 EchoServerImpl_Stub.class。之后我运行“rmiregistry”，然后启动 RMIServer。在那一刻，我看到 ServerException：

java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: 
    java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
    java.lang.ClassNotFoundException: test.EchoServerImpl_Stub
    at sun.rmi.server.UnicastServerRef.oldDispatch(Unknown Source)
    at sun.rmi.server.UnicastServerRef.dispatch(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 Source)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
    at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255)
    at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233)
    at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:359)
    at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
    at java.rmi.Naming.rebind(Naming.java:160)
    at test.RMIServer.(RMIServer.java:10)
    at test.RMIServer.main(RMIServer.java:17)
    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.intellij.rt.execution.application.AppMain.main(AppMain.java:90)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
    java.lang.ClassNotFoundException: test.EchoServerImpl_Stub
    at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source)
    at sun.rmi.server.UnicastServerRef.oldDispatch(Unknown Source)
    at sun.rmi.server.UnicastServerRef.dispatch(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 Source)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: test.EchoServerImpl_Stub
    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 java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClassInternal(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(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)
    ... 12 more  

我认为这是一个常见问题，它可能与错误的部署有关。如何修复它？

Answer 1

我认为这是您的 rmiregistry 类路径。 test.EchoServer 接口需要可供 rmiregistry 本身访问。在运行rmiregistry之前设置您的CLASSPATH环境变量，例如

C:\>set CLASSPATH="MyBinFolder"
C:\>rmiregistry

此外，rmic是Java 5之前的遗留问题。没有必要不再运行它了。只需正常运行服务器和客户端，代理就会动态创建。

问候，
MK