Kryo中的序列化事件

Question

void writeObject(ObjectOutputStream out) {
  // handle event
  out.defaultWriteObject(this);
}

Serializer def = kryo.getDefaultSerializer(A.class)
kryo.addDefaultSerializer(A.class, new Serializer() {
    public void write(Kryo kryo, Output output, Object object) {
        ((A)object).serializationEvent();
        def.write(kryo, output, object);

Answer 1

我发现了两个解决办法。首先，重写writeReferenceOrNull可以工作

Kryo kryo = new Kryo() {
    public boolean writeReferenceOrNull (Output output, Object object, boolean mayBeNull) {
        if (object instanceof A) {
            ((A) object).serializationEvent();
        }

        return super.writeReferenceOrNull(output, object, mayBeNull);
    }

但是，它需要更改源代码可见性，Natan说，只有在启用引用时（在默认情况下），这才有效，并建议使用一种更可靠的方法：重写NewDefaultSerializer：

public class EventFiringKryo extends Kryo {
    protected Serializer newDefaultSerializer(Class type) {
        final Serializer def = super.newDefaultSerializer(type);
        Serializer custom = new Serializer() {

            public void write(Kryo kryo, Output output, Object object) {
                System.err.println("writing " + object + ":" + object.getClass().getSimpleName());
                if (object instanceof A)
                    ((A)object).serializationEvent();
                def.write(kryo, output, object);
            }

            public Object read(Kryo kryo, Input input, Class type) {
                Object result = def.read(kryo, input, type);
                if (result instanceof SomeAnotherType)
                    result.canInitializeSomethingElse();
                return result;
            }
        };
        return custom;
    }

}

除了有效之外，这种方法还不需要仔细注册实现要调用的接口的所有类。