myobjectinputstream.java

JAVA网络编程技术内幕一书的源代码

/*
 * Java Network Programming, Second Edition
 * Merlin Hughes, Michael Shoffner, Derek Hamner
 * Manning Publications Company; ISBN 188477749X
 *
 * http://nitric.com/jnp/
 *
 * Copyright (c) 1997-1999 Merlin Hughes, Michael Shoffner, Derek Hamner;
 * all rights reserved; see license.txt for details.
 */

import java.io.*;
import java.net.*;

public class MyObjectInputStream extends ObjectInputStream implements MyOSConstants {
  public MyObjectInputStream (InputStream in) throws IOException {
    super (in);
    enableResolveObject (true);
  }

  protected void readStreamHeader () throws IOException {
    super.readStreamHeader ();
    if (readShort () != myOSMagick)
      throw new StreamCorruptedException
        ("Incompatible myOSMagick number");
    if (readShort () > myOSVersion)
      throw new StreamCorruptedException
        ("Incompatible myOSVersion number");
  }

  protected Object resolveObject (Object object) throws IOException {
    if (object instanceof MyDatagramPacket)
      return ((MyDatagramPacket) object).toDatagramPacket ();
    else
      return object;
  }
}