RMI: rmi server 是否只能同时使用一个网络接口

Question

我有 rmi 服务器，并且我的计算机上有几个网络适配器。

为了不得到java.rmi.ConnectException: Connection refused to host: 127.0.1.1;，我需要在我的rmi服务器上设置java.rmi.server.hostname属性（见https://stackoverflow.com/a/15696021/5057736）

这是否意味着在一个 JVM 实例中，rmi 服务器同时只能使用一个网络接口而无需任何操作系统设置？

Answer 1

设置java.rmi.server.hostname 只会影响写入存根的内容。对听力没有影响。 RMI 始终在 0.0.0.0 进行侦听，除非您使用不这样做的 RMIServerSocketFactory。

Answer 2

在阅读https://community.oracle.com/blogs/emcmanus/2006/12/22/multihomed-computers-and-rmi 和这个https://community.oracle.com/thread/1178328?start=0 之后，我做了以下解决方案 - 在所有应用程序中导出 RMIRemoteObjects 我们放在一个地方。此解决方案允许 RMI 在一个 JVM 实例中同时使用不同的网络接口。为每个套接字地址（网络接口 + 端口）创建 RmiRemoteManager。在导出之前我们需要定义java.rmi.server.hostname。此解决方案有效。请记住，这是 RMI 限制的解决方法。

class ClientSocketFactory implements RMIClientSocketFactory,Serializable{

    private InetAddress address;

    public ClientSocketFactory(InetAddress address)
    {
        this.address = address;
    }

    @Override
    public Socket createSocket(String host, int port) throws IOException {
        Socket socket =new Socket(address, port);
        return socket;
    }

    @Override
    public boolean equals(Object that)
    {
        return that != null && this.getClass() == that.getClass();
    }
}

class ServerSocketFactory implements RMIServerSocketFactory{

    private InetAddress address;

    public ServerSocketFactory(InetAddress address)
    {
        this.address = address;
    }

    @Override
    public ServerSocket createServerSocket(int port) throws IOException{  
        return new ServerSocket(port, 0, address);
    }

    @Override
    public boolean equals(Object that)
    {
        return that != null && this.getClass() == that.getClass();
    }
}

public class RmiRemoteManager {

    private Registry registry;

    private InetSocketAddress socketAddress;

    private ServerSocketFactory serverSocketFactory;

    private ClientSocketFactory clientSocketFactory;

    public RmiRemoteManager(InetSocketAddress socketAddress) {
        try {
            this.socketAddress = socketAddress;
            serverSocketFactory=new ServerSocketFactory(InetAddress.getByName(socketAddress.getHostName()));
            clientSocketFactory=new ClientSocketFactory(InetAddress.getByName(socketAddress.getHostName()));
            //the registry is exported via createRegistry.
            registry = LocateRegistry.createRegistry(this.socketAddress.getPort(),clientSocketFactory,serverSocketFactory);
        } catch (UnknownHostException ex) {
            Logger.getLogger(RmiRemoteManager.class.getName()).log(Level.SEVERE, null, ex);
        } catch (RemoteException ex) {
            Logger.getLogger(RmiRemoteManager.class.getName()).log(Level.SEVERE, null, ex);
        }

    }

    private synchronized static Remote export(Remote remoteObject,InetSocketAddress sa,ClientSocketFactory csf,ServerSocketFactory ssf){
        try {
            System.setProperty("java.rmi.server.hostname",sa.getHostName());
            return UnicastRemoteObject.exportObject(remoteObject,sa.getPort(),csf,ssf);
        } catch (RemoteException ex) {
            Logger.getLogger(RmiRemoteManager.class.getName()).log(Level.SEVERE, null, ex);
        }
        return null;
    }

    public void export(Remote remoteObject,String url){
        try {
            Remote stub=export(remoteObject,socketAddress,clientSocketFactory,serverSocketFactory);
            remoteObjects.add(remoteObject);
            if (url!=null){
                urlsByRemoteObjects.put(remoteObject, url);
                registry.rebind(url, stub);
            }
        } catch (RemoteException ex) {
            Logger.getLogger(RmiRemoteManager.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}