How to convert an Object to byte[]

Question

How do I convert an object to a byte array without using the ObjectOutputStream?
I need to send an object over UDP socket which only works with byte[].

Answer 1

instead of serialisation for complex object i usexm and sax to transfer information over the network,
it works great
works nothing when transfering over the ORBWhen programming with a socket, sendTo is a standard function used in the connectionless protocol. I rewrote this function so as to be able to transmit objects. The following code example shows how to implement the send method in a Sender class:
import java.io.*;
import java.net.*;
public class Sender
{  public void sendTo(Object o, String hostName, int desPort) 
{    try   
{      InetAddress address = InetAddress.getByName(hostName);
ByteArrayOutputStream byteStream = new
ByteArrayOutputStream(5000);
ObjectOutputStream os = new ObjectOutputStream(new
BufferedOutputStream(byteStream));
os.flush();
os.writeObject(o);
os.flush();
//retrieves byte array
byte[] sendBuf = byteStream.toByteArray();
DatagramPacket packet = new DatagramPacket(
sendBuf, sendBuf.length, address, desPort);
int byteCount = packet.getLength();
dSock.send(packet);
os.close();
catch (UnknownHostException e)
System.err.println("Exception: " + e);
e.printStackTrace(); }
catch (IOException e) { e.printStackTrace();
The code listing below demonstrates how to implement a receive method in a Receiver class. Method recvObjFrom is for the receiver to receive the object. You can include this method in your code to receive runtime objects.
import java.io.*;
import java.net.*;
public class Receiver
{  public Object recvObjFrom() 
{    try
byte[] recvBuf = new byte[5000];
DatagramPacket packet = new DatagramPacket(recvBuf,
recvBuf.length);
dSock.receive(packet);
int byteCount = packet.getLength();
ByteArrayInputStream byteStream = new
ByteArrayInputStream(recvBuf);
ObjectInputStream is = new
ObjectInputStream(new BufferedInputStream(byteStream));
Object o = is.readObject();
is.close();
return(o);
catch (IOException e)
System.err.println("Exception: " + e);
e.printStackTrace();
catch (ClassNotFoundException e)
{ e.printStackTrace(); }
return(null); }
One may worry about the size of the byte array -- because when you construct ByteArrayOutputStream or ByteArrayInputStream, you have to specify the size of the array. Since you don't know the size of a runtime object, you will have trouble specifying that size. The size of a runtime object is often unpredictable. Fortunately, Java's ByteArrayInputStream and ByteArrayOutputStream classes can extend their sizes automatically whenever needed.
By
Sree Visveswaran