序列化对象丢失数据

Question

我创建了一个通过RMI进行通信的Java Server和Client应用程序。 为了让客户端“满足”服务器，我正在向客户端发送多播DatagramPacket。 发生的事情是我使用属性localDirectory实例化类，当我收到它时，它来自null。 重要的是，我正在尝试发送的对象实现了Seriaizable。

你觉得我做错了什么？

（如果您需要aditional代码让我知道）

public static void main(String[] args) throws RemoteException {




localDirectory = new File("c:\\tempfiles".trim());

serverToTransmit = (ServerInterface) new Server(localDirectory);


if (!localDirectory.exists()) {
    System.out.println("Directory " + localDirectory + " does NOT exist!");
    return;
}

if (!localDirectory.isDirectory()) {
    System.out.println("The path " + localDirectory + " is NOT a directory!");
    return;
}

if (!localDirectory.canRead()) {
    System.out.println("WITHOUT reading permissions on " + localDirectory + "!");
    return;
}

try {
     System.out.println("Vou criar o registry");
    Registry registry;

    try {

        System.out.println("Registry lauching try in port " + 7609 + "...");

        registry = LocateRegistry.createRegistry(7609);

        System.out.println("Registry launched!");
    } catch (RemoteException e) {

        System.out.println("Registry probably in execution already!");
        registry = LocateRegistry.getRegistry();
    }

                 System.out.println("Será que criei?");

    //Create Service
    //ServerInterface service = new Server(localDirectory);
    Server server = new Server(localDirectory);

    registry.bind(SERVICE_NAME, server);

    System.out.println("Service " + SERVICE_NAME + " registered on registry.");


    MulticastSocket sock = new MulticastSocket(7000);   //225.15.15.15 e o porto 7000.
    InetAddress addr = InetAddress.getByName("225.15.15.15");
    sock.joinGroup(addr);
    //sock.setTimeToLive(1);
    DatagramSocket psock;
    while (true) {

        try {
            ByteArrayOutputStream bOut = new ByteArrayOutputStream();
            ObjectOutputStream out = new ObjectOutputStream(bOut);
            out.writeObject(serverToTransmit);
            //out.writeUnshared(objectToTransmit) in order to avoid caching issues
            out.flush();
            byte[] data = bOut.toByteArray();
            DatagramPacket packet = new DatagramPacket(data, data.length, addr, 7000);
            System.out.println("sizeeee: " + bOut.size());
            sleep(3000);
            sock.send(packet);
        } catch (SocketException ex) {
            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
        }

    }

    /*   if (args.length > 0 && args[0].equals("leader")) {
    playLeader(sock, psock, addr);
} else {
    playFollower(sock, psock, addr);
}
sock.leaveGroup(addr);*/
} catch (RemoteException e) {

    System.out.println("Remote error - " + e);
    System.exit(1);
} catch (Exception e) {

    e.printStackTrace();
}

我在这样的客户端收到它（只提供重要的代码）：

MulticastSocket sock = new MulticastSocket(7000);   //225.15.15.15 e o porto 7000.
                    InetAddress addr = InetAddress.getByName("225.15.15.15");
                    sock.joinGroup(addr);

                    sock.setTimeToLive(1);

                    System.out.println("PASSOU AQUI_!");
                    DatagramPacket packet = new DatagramPacket(new byte[1024], 1024, addr, 7000);
                    sock.receive(packet);
                     System.out.println("PASSOU AQUI_1!");
                    ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(packet.getData(), 0,
                            packet.getLength()));
                     System.out.println("PASSOU AQUI_2!");
                    ServerInterface returnedObject = (ServerInterface) in.readObject();
                    System.out.println("Returned Object LOCAL DIR -> " + returnedObject.getLocalDirectory());

谢谢！

Answer 1

因此，为了涵盖所有可能性，包括一些被您的问题排除的可能性，属性localDirectory ：

• 序列化时为null
• 是static
• 是transient
• 不是由自定义writeObject()方法编写的
• 未由自定义readObject()方法分配
• 甚至没有出现在序列化的类的版本中，但是在反序列化的版本中
• 在writeReplace()/readResolve() megillah中丢失了。