Question

我在很长一段时间内收到NotSerializableException。完整的错误是这样的

java.io.NotSerializableException: sun.java2d.SunGraphics2D
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at SOM_thread1.run(soms1.java:354)

错误在out.writeObject（g）上; 完整代码如下

public class soms1 extends JApplet implements Serializable {

/**
 * 
 */
private static final long serialVersionUID = -743443566771258883L;

// class of weights and samples which performs operations on the SOM
public static Screen screen = new Screen();

// Socket Connection 
private static Socket clientSocket = null;
private static PrintStream os = null;
private static BufferedReader inputLine = null;


// thread responsible for updating Screen
static public SOM_thread1 thread = null;

Toolkit tool;

public void init() {
    String sentence;
    tool = Toolkit.getDefaultToolkit();

    try {
        clientSocket = new Socket("localhost", 6789);
        thread = new SOM_thread1(clientSocket);
        setup_applet();
        setup_radios();
        setup_layout();

        screen.init_Screen();

        thread.init();
        thread.start();

        inputLine = new BufferedReader(new InputStreamReader(System.in));
        sentence = inputLine.readLine();
        if (clientSocket != null && os != null
                && sentence.equals("server:apl")) {
            thread.set_state(2);
        }
    } catch (UnknownHostException e) {
        System.err.println(e);
    } catch (IOException e) {
        System.err.println(e);
    }
}

}

class SOM_thread1 extends Thread implements Serializable{

/**
 * 
 */
private static final long serialVersionUID = 1L;

int state = -1;
int MAX_ITER = 0;
float t;
float T_INC;
private ObjectOutputStream out = null;
private Socket clientSocket = null;
public transient Graphics g = null;

public SOM_thread1(Socket clientSocket) {
    this.clientSocket = clientSocket;
}
/*Updates the class Screen according the to values retrieved from the user interface*/
public void run() {
    while (true) {
        // Send data to server
        try {
            g = soms1.screen.getGraphics();
            out = new ObjectOutputStream(clientSocket.getOutputStream());
            out.writeObject(g);
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // Allow other operations
        yield();
    } // while(true)

}
}

请通知我应该序列化哪个对象提前谢谢

Answer 1

您无法（有用）序列化Thread子类。 Thread超类包含本身不可序列化的状态。

实际的异常正在发生，因为这一行：

          out.writeObject(g);

明确尝试序列化sun.java2d.SunGraphics2D实例。它不可序列化。您可以做的最好的事情是尝试在反序列化的上下文中创建一个新的Graphics对象。

FWIW，你的代码有很多对我来说没什么意义。序列化Graphics对象有什么意义？你究竟想要实现什么目标？

我正在尝试通过图形对象将图形数据发送到服务器。因为我使用了sun.java2d.SunGraphics2D提供的Screen.getGraphics（）方法。 screen只是一种生成图形地图的显示方法。

基本上，你要做的事情是不可能的。无法通过图形API以允许您在新设备上重建它的形式检索Graphics对象的状态（即屏幕上显示的内容）。

您应该以原始形式序列化您在设备上呈现的源数据，并在对其进行反序列化后重新呈现它。

Answer 2

好吧，你正在编写g方法返回的对象Screen.getGraphics()，我假设（来自堆栈跟踪）返回类sun.java2d.SunGraphics2D的实例。

如果你看一下它的签名

public final class SunGraphics2D extends java.awt.Graphics2D implements sun.awt.ConstrainableGraphics, java.lang.Cloneable, sun.java2d.DestSurfaceProvider {

你会发现它没有实现Serializable而且它是final，所以看起来你运气不好......

获取NotSerializableException：sun.java2d.SunGraphics2D

2 个答案: