Reading Objects using NIO

Question

I having problems reading an object using NIO APIs. I am end creating an Object and pass it through a socket. When I retrieve the data from the input stream within the socket I initialize a ByteBuffer by allocating a length. The problem is that there is NO way of knowing what to allocate that ByteBuffer when reading in the object. Below is within a method that allows me to read information from the socket.
//Allocate the length ByteBuffer.
ByteBuffer buffer = ByteBuffer.allocate(1024);
//Read the data from the SocketChannel....PROBLEM IS WHAT IF I NEED TO DO MULTIPLE READS
socketChannel.read(buffer);
///We will create a byte array from the ByteBuffer.
byte[] b = buffer.array();
//ByteArrayInputStream that we will create and put the byte array in.
ByteArrayInputStream bis = new ByteArrayInputStream(b);
//ObjectInputStream where we will use the ByteArrayInputStream.
ObjectInputStream input = new ObjectInputStream(bis);
//Object that we will read in.
Object obj = input.readObject();
//Message that we will end up receiving.     
Message receivingMsg = null;
//Once we have our Message we will end up closing the connection.
bis.close();
input.close();
//We will clear the buffer.
buffer.clear();
//We will cast the object to a message object so
//that we can end up sending it through the right
//routine which will allow us to send a response
//back to the client. *********SPECIAL Class that will cast our generic object into a Message Object.
Message receivedFromClient = (Message) obj;
//we will end up taking that message and returning it.
Message returningMsg = communicate(receivedFromClient);
//Here we will end up taking the Message and putting it into the ByteBuffer.          
ByteBuffer bb = objectToOutputStreamByteBuffer(returningMsg);
socketChannel.write(bb);
----The problem is if I have more data within that Object. I need to re-allocate the ByteBuffer object and read everything on that socket. I tried the following code but I really don't feel it will be optimized the best for performance. I guess my question is that should I even be using NIO in this situation or Blocking IO?
Again, here is the code that will read multiple data from the socket until it is -1.
//Here we will read the information we received by first allocating
//a ByteBuffer object.
ByteBuffer buffer1 = ByteBuffer.allocate(5);
ByteBuffer buffer2 = ByteBuffer.allocate(0);
//We will read the data from this object.
while ((socketChannel.read(buffer1)) != -1) {
//We will check the Buffers and then try to recreate a new ByteBuffer that will put the remaining
//stuff within the buffer. NOT SURE IF THIS IS THE MOST EFFICIENT WAY OF DOING THIS
//AND ACTUALLY DON'T HAVE THE CODE WORKING CORRECTLY. THIS IS WHERE I
//NEED HELP ON THE CORRECT WAY TO DO THIS.
     if (buffer1.remaining() < buffer2.remaining()) {
          buffer1.flip();
          buffer2 = ByteBuffer.allocate(buffer1.remaining() + buffer2.remaining());
          System.out.println("tmp 2 Remaining : " + buffer2.remaining());
          //tmp.put(buffer2);
          //buffer2 = tmp;
          System.out.println("Buffer 2 Remaining : " + buffer2.remaining());
     buffer2.put(buffer1);
     buffer1.clear();
//We will create a byte array from the ByteBuffer.                    
byte[] b = buffer.array();
//ByteArrayInputStream that we will create and put the byte array in.
ByteArrayInputStream bis = new ByteArrayInputStream(b);
//ObjectInputStream where we will use the ByteArrayInputStream.
ObjectInputStream input = new ObjectInputStream(bis);
//Object that we will read in.
Object obj = input.readObject();
//Message that we will end up receiving.     
Message receivingMsg = null;
//Once we have our Message we will end up closing the connection.
bis.close();
input.close();
//We will clear the buffer.
buffer2.clear();
buffer1.clear();
//We will cast the object to a message object so
//that we can end up sending it through the right
//routine which will allow us to send a response
//back to the client.
Message receivedFromClient = (Message) obj;
//we will end up taking that message and returning it.
Message returningMsg = communicate(receivedFromClient);
//Here we will end up taking the Message and putting it into the ByteBuffer.          
ByteBuffer bb = objectToOutputStreamByteBuffer(returningMsg);
socketChannel.write(bb);
Any help would be greatly appreciated.

Answer 1

I use my own InputStream class overriding the two standard read functions read( byte[], index, length ) and read(). When you construct it pass in the channel you are reading from and read from the channel on demand. ie when a call to read comes in you read say 100 bytes from the channel. The call required only 80 so these are consumed and the other 20 are buffered. Another read call is made, this time for 50 bytes but we only have 20 buffered so another read of the channel is needed. It is up to you whether you break the contract of read( byte[], index, length ) to keep reading the channel until the full "length" is available, or handle this in your application code.
Then because this class is InputStream you can wrap it up inside any stream you like such as the ObjectInputStream and the data will be serialized correctly.