java - ObjectInputStream 返回一个空对象

Question

所以我试图将一个对象从客户端发送到服务器，然后我用这个对象做一些事情。我验证了发送时对象包含数据。当我在调试器中读取对象时，它的所有属性均为 null。

下面是我发送对象的位置:

private class registerUser extends Task<Void>
{
        Users user;
        private static final String code = ".register";
        private static final String host = "localhost";
        private static final int portNumber = 4444;
        private clientThread clientThread;


    public registerUser(Users user)
    {
        this.user = user;
    }

    @Override
    protected Void call() throws Exception
    {
        try
        {
            Socket socket = new Socket(host, portNumber);
            Thread.sleep(1000);

            //Setup I/O
            ObjectOutputStream outToServerObject = new ObjectOutputStream(socket.getOutputStream());
            //PrintWriter serverOutString = new PrintWriter(socket.getOutputStream(), false);
            InputStream serverInString = socket.getInputStream();

            //serverOutString.println(code);
           // serverOutString.flush();

            outToServerObject.writeObject(user);
            outToServerObject.flush();
        }
        catch (IOException e)
        {
            System.err.println("Fatal Connection error!");
            e.printStackTrace();
        }
        return null;
    }

当我按下 GUI 中的按钮时，就会使用上述任务，如下所示:

public void btn_registerUser(ActionEvent actionEvent) throws IOException
{

        user.setUserName(txt_Username.getText());
        user.setFirstName(txt_FirstName.getText());
        user.setLastName(txt_LastName.getText());
        user.setCity(txt_City.getText());
        user.setBirthday(date_Birthday.getValue());


        Task<Void> task = new registerUser(user);
        Thread thread = new Thread(task);
        thread.setDaemon(true);
        thread.start();

}

接收对象的服务器中的代码:

//Setup I/O
this.clientOut = new PrintWriter(socket.getOutputStream(), false);
ObjectInputStream inFromClientObject = new ObjectInputStream(socket.getInputStream());


// Scanner in = new Scanner(socket.getInputStream());
Users user = (Users) inFromClientObject.readObject();
doSomething(user);

还有 User.java 类，它是争论中的对象

public class Users implements Serializable
{

    /*
    Variables
    TODO Create a friend list
    */
    private transient IntegerProperty userID;
    private transient StringProperty userName;
    private transient StringProperty firstName;
    private transient StringProperty lastName;
    private transient StringProperty city;
    private transient ObjectProperty<LocalDate> birthday;
    private transient ListProperty<String> musicGenre;
    private transient List<String> musicGenres = new ArrayList<>();
    /**
     * Default constructor.
     */
    public Users()
    {
        this(null,null,null,null,null);
    }

    /**
     * Constructor with some initial data.
     * Takes in a {@code String} and sets a reference
     *
     * @param userName
     *
     */
    public Users(String userName,  String firstName, String lastName, String city, LocalDate birthday)
    {
        this.userName = new SimpleStringProperty(userName);
        this.userID = new SimpleIntegerProperty();
        this.firstName = new SimpleStringProperty(firstName);
        this.lastName = new SimpleStringProperty(lastName);
        this.city = new SimpleStringProperty(city);
        this.birthday = new SimpleObjectProperty<LocalDate>(birthday);
        ObservableList<String> observableList = FXCollections.observableArrayList(this.musicGenres);
        this.musicGenre = new SimpleListProperty<String>(observableList);

    }
}

我省略了 getter 和 setter，因为这个问题已经很长了

因此，在调试器中运行服务器时，当我doSomething(user)

时，用户的所有属性均为空

*编辑这些建议正在发挥作用，但我遇到了问题

private List<String> musicGenreList = new ArrayList<>();
ObservableList<String> observableList = FXCollections.observableArrayList(musicGenreList);
private ListProperty<String> musicGenre = new SimpleListProperty<String>(observableList);

这是我向 ListProperty 添加项目的唯一方法，但 observableList 无法序列化

Answer 1

就像 James_D 所说，基本上我必须创建自定义 WriteExternal 和 ReadExternal

在Users.java中需要进行更改

public class Users implements Externalizable
{
    public Users(String userName,  String firstName, String lastName, String city, LocalDate birthday)
    {
        setUserName(userName);
        setFirstName(firstName);
        setBirthday(birthday);
    }

    private IntegerProperty userID = new SimpleIntegerProperty(this, "id");
    private StringProperty userName = new SimpleStringProperty(this, "userName');
    private ObjectProperty<LocalDate> birthday = new SimpleObjectProperty<>(this, "birthday");

    //Create setters and getters...

    @Override
    public void writeExternal(ObjectOutput out) throws IOException
    {
        out.writeInt(getUserID());
        out.writeObject(getUserName());
        out.writeObject(getBirthday());
    }

    @Override
    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
    {
        setUserID((int) in.readInteger());
        setUserName((String) in.readObject());
        setBirthday((LocalDate) in.readObject());
    }
}

但是我无法使用以下方法序列化 ListProperty

private ObservableList<String> observableList = FXCollections.observableArrayList();
private ListProperty<String> newList = new SimpleListProperty<>(this, "musicGenre", observableList);

根据我的需要，ListProperty 需要以这种方式实例化，因为我需要使用 user.newListProperty().get().add("String") 向其中添加字符串项，并且无需使用ObservableList 我不能这样做

如果有人知道解决这个问题的方法，我们将不胜感激