RMI 绑定失败并出现“java.lang.ClassNotFoundException: rmtest.IRemote”

Question

我在将远程对象绑定到 RMI 注册表时遇到问题。我已将我的代码简化为一个非常简单的示例，当我在我的计算机（Windows 10）上测试它时可以正常工作。但是如果我在另一台计算机（Windows 7）上启动它，当registry.bind(id, remoteObject); 被调用时，我会得到这个异常：

java.lang.ClassNotFoundException: 
rmitest.IRemote (no security manager: RMI class loader disabled)

我不需要 SecurityManager，因为所有类文件都在 jar 中，我不想使用动态代码加载功能。

为什么它会尝试加载安全管理器，为什么即使我定义了它也找不到？它可以在一台机器上运行但不能在另一台机器上运行的原因可能是什么？我认为代码是好的，它必须是一些配置问题，但我不确定究竟是什么配置错误。

这里是远程接口和远程对象实现，我在 Eclipse 中导出为可运行 Jar 为 rmitest.jar。

public interface IRemote extends Remote {
    void foo() throws RemoteException;
}

public class RemoteImpl extends UnicastRemoteObject implements IRemote {

    private static Registry     registry;

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

    public static void main(final String[] args) throws Exception {
        try {
            LocateRegistry.createRegistry(Registry.REGISTRY_PORT);
        } catch (final Exception e) {
            // already created
        }
        registry = LocateRegistry.getRegistry(Registry.REGISTRY_PORT);
        registry.bind(UUID.randomUUID().toString(), new RemoteImpl());
        System.out.println("Binding successful");
    }

    @Override
    public void foo() throws RemoteException {
        System.out.println("foo");
    }
}

这是完整的堆栈跟踪，它在调用registry.bind 的行中抛出，并且在使用以下任一命令运行时完全相同： java -jar rmitest.jar 或
java -Djava.security.manager -Djava.security.policy=policy -jar rmitest.jar

很奇怪，显然在这两种情况下都需要安全管理器，但即使在第二种情况下也找不到安全管理器。

Exception in thread "main" java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: 
    java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
    java.lang.ClassNotFoundException: rmitest.IRemote (no security manager: RMI class loader disabled)
    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 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$ConnectionHandler.lambda$run$256(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
    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(StreamRemoteCall.java:276)
    at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:253)
    at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:379)
    at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
    at rmitest.RemoteImpl.main(RemoteImpl.java:29)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: 
    java.lang.ClassNotFoundException: rmitest.IRemote (no security manager: RMI class loader disabled)
    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 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$ConnectionHandler.lambda$run$256(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
    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: rmitest.IRemote (no security manager: RMI class loader disabled)
    at sun.rmi.server.LoaderHandler.loadProxyClass(Unknown Source)
    at java.rmi.server.RMIClassLoader$2.loadProxyClass(Unknown Source)
    at java.rmi.server.RMIClassLoader.loadProxyClass(Unknown Source)
    at sun.rmi.server.MarshalInputStream.resolveProxyClass(Unknown Source)
    at java.io.ObjectInputStream.readProxyDesc(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)
    ... 15 more

这是策略文件，它应该允许一切：

grant {
  permission java.security.AllPermission;
};

Answer 1

问题在于“其他 Java 进程”提供了自己的注册表，它无法访问您的 CLASSPATH。你会发现，如果你有比createRegistry() 的空catch 块更好的东西。

Answer 2

问题是其他一些正在运行的 Java 进程似乎干扰了注册表绑定。我不知道这个流氓进程到底做了什么，但杀死它解决了错误。不需要安全管理器，现在只需像往常一样运行 jar。