java - RMI 绑定(bind)失败并显示 "java.lang.ClassNotFoundException: rmitest.IRemote"

Question

我在将远程对象绑定(bind)到 RMI 注册表时遇到问题。我已将代码简化为一个非常简单的示例，当我在计算机(Windows 10)上测试它时，它运行良好。但是，如果我在另一台计算机(Windows 7)上启动它，当调用 registry.bind(id, remoteObject); 时，我会收到此异常:

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，并且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安全管理器也找不到安全管理器？它在一台机器上运行但在另一台机器上运行失败的原因可能是什么？我认为代码是好的，它一定是一些配置问题，但我不确定到底是什么配置错误。

这是远程接口(interface)和远程对象实现，我将其导出为 Eclipse 中的可运行 Jar，即 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，并且与使用以下命令运行时完全相同:java -jar rmtest.jar 或
java -Djava.security.manager -Djava.security.policy=policy -jar rmitest.jar

很奇怪的是，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

问题是“其他一些 Java 进程”提供了自己的注册表，它无法访问您的 CLASSPATH。您会发现，如果您有比 createRegistry() 的空 catch block 更好的东西。