java - 为什么 Java RMI 回调在 NAT 路由器后面不起作用？

Question

我正在尝试使用一个简单的程序在 Java RMI 上进行回调，并且它在 localhost 和 LAN 中运行良好，但是在 NAT 路由器后面执行此操作时遇到问题。

如果我的服务器实现，我会被拒绝连接extends UnicastRemoteObject。如果我不这样做extends UnicastRemoteObject并手动导出对象UnicastRemoteObject.exportObject(services, 0);（

我像这样在注册表中绑定服务：

public class Server {
    private static final String SRVHOST = "<<external ip>>";
    private static Registry registry;

    public static void main(String[] args) {
        System.setProperty("java.rmi.server.hostname", SRVHOST);
        System.setProperty("java.rmi.server.useCodebaseOnly","false"); 
        System.setProperty("java.security.policy","src/srv.policy");

        if(System.getSecurityManager()==null)
            System.setSecurityManager(new RMISecurityManager());

        registry = LocateRegistry.createRegistry(Registry.REGISTRY_PORT);
        ServerInterface services = new ServerImpl();
        registry.rebind("ServerAPI", services);
    }
}

客户获得服务：

public class Client {
    private static final String SRVHOST = "localhost";
    private static Registry registry;
    private static ClientInterface callback;

    public static void main(String[] args) {
        System.setProperty("java.security.policy", "src/cli.policy");

        if(System.getSecurityManager()==null)
            System.setSecurityManager(new RMISecurityManager());


        registry = LocateRegistry.getRegistry(SRVHOST, Registry.REGISTRY_PORT);
        ServerInterface services = (ServerInterface) registry.lookup("ServerAPI");
        callback = new ClientImpl();
        int nCallback = services.setClientInterface(callback);
        ...
        <<do_things>>
    }
}

该方法setClientInterface(...)获取客户端对象并将其存储在ArrayList.

我不知道有什么问题。有人能帮我吗？

所有代码都在这里发布：

政策文件：

srv.policy - http://pastebin.com/LTsKSG3r

cli.policy - http://pastebin.com/zqxaRyT3

包：com.rmcallback.client

Client.java - http://pastebin.com/Xus04JZK

ClientImpl.java - http://pastebin.com/SdQXMDzs

ClientInterface.java - http://pastebin.com/S9PxT5vC

包：com.rmcallback.server

Server.java - http://pastebin.com/cxQcWy1Q