Is there a way to determine the generated serialVersionUID
of a serialized Java object?
The problem is that I serialized an object without explicitely specifying the serialVersionUID
. Now the deserialization process complains about class incompatibilities. However I didn't change the class in a way which would make it incompatible. So I assume that it is enough to specify the serialVersionUID
in the class as it is stored in the object data. In order to do this I need to read the serialVersionUID
from the serialized data.
You can do this by extending ObjectInputStream:
public class PrintUIDs extends ObjectInputStream {
public PrintUIDs(InputStream in) throws IOException {
super(in);
}
@Override
protected ObjectStreamClass readClassDescriptor() throws IOException,
ClassNotFoundException {
ObjectStreamClass descriptor = super.readClassDescriptor();
System.out.println("name=" + descriptor.getName());
System.out.println("serialVersionUID=" + descriptor.getSerialVersionUID());
return descriptor;
}
public static void main(String[] args) throws IOException,
ClassNotFoundException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(baos);
List<Object> list = Arrays.asList((Object) new Date(), UUID.randomUUID());
oos.writeObject(list);
oos.close();
InputStream in = new ByteArrayInputStream(baos.toByteArray());
ObjectInputStream ois = new PrintUIDs(in);
ois.readObject();
}
}
I believe it would be possible to read all the serialized data by replacing the descriptor returned by the method, but I haven't tried it.