如何使继承可序列化 class 的 class 不能序列化？

Question

Let's consider the following code:

public class MyPanel extends JPanel {

    private long secretInfo = ...

}

JPanel is Serializable . However, MyPanel should not be Serializable ever, because it contains sensitive information.

How to cleanly cancel/prevent the inherited Serializable aspect from JPanel ?

Answer 1

You mark the fields you don't want to serialize as transient :

private transient long secretInfo = ...  

You can still serialize MyPanel , but its sensitive information won't be serialized.

Also, you could consider an alternative design where the sensitive information is stored in a separate non-serializable class.

Answer 2

You can use one of the following approaches:

public class MyPanel extends JPanel {
    private long secretInfo = ...

    // refuse to be serialized!
    private void writeObject(ObjectOutputStream out) throws IOException {
        throw new IllegalStateException("MyPanel cannot be serialized");
    }
}

or

public class MyPanel extends JPanel {
    // flag the serialization mechanism to ignore
    // sensitive information
    private transient long secretInfo = ...
}

Answer 3

Don't extend JPanel. Problem solved. Try something like this instead:

class MyPanel {
    void doSomething();
    String getSomeValue();
    JPanel getDisplayComponent();
}

MyPanel logically represents a panel in your app, but there's no particular requirement for it to extend JPanel. Composition is often a more powerful relationship.