CS 596: Java Network Q and A

CS 596 Client-Server Programming
Java Network Q and A

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San Diego State University -- This page last updated March 5, 1996

Contents of Java Network Q and A Lecture

Java Networking Q and A

Java Networking Q and A

Q - How Do I open a Socket?

In a client:

	Socket	aSocket = null;

	aSocket = new Socket(serverName, portNumber);

In a server:

	ServerSocket  aSocket = null;

	try 
		{
		aSocket = new ServerSocket(  portNumber  );
		} 
	catch (IOException e)

Q - How do I use a Socket to communicate with a Server or Client?

Step 1

Get the input and/or output streams from the socket

Step 2

Read the input stream if you are excepting data
Write to the output stream if you need to send data

Q - How do I get the input and output streams from a socket?

	InputStream  in  =  aSocket.getInputStream();
	OutputStream  out  =  aSocket.getOutputStream();

Q - How do I read from an input stream?

There are various ways. Here is one way to read from an input stream that is connected to a socket. You can also deal with bytes.

	InputStream  in  =  aSocket.getInputStream();

	// Buffering is a good idea when dealing with a network
	BufferedInputStream  bufferedIn; 
	bufferedIn  =  new BufferedInputStream(  bufferedIn  );

	// ASCIIInputStream make is easy to read from the stream
	ASCIIInputStream  cin;
	cin  = new ASCIIInputStream( bufferedIn  );

Now you can use any of the ASCIIInputStream methods like readLine() and readInt()

	String  message  =  cin.readLine();

Q - How do I write to an output stream?

There are various ways. Here is one way to write to an output stream that is connected to a socket.

	OutputStream  out  =  aSocket.getOutputStream();

	// Buffering is a good idea when dealing with a network
	BufferedOutputStream  bufferedOut; 
	bufferedOut  =  new BufferedOutputStream(  bufferedOut  );

	// PrintStream make is easy to write to a stream
	PrintStream  cout;
	cout  = new PrintStream( bufferedOut,  false  );

Now you can use the PrintStream methods print() and println().

	cout.println( " Hi Mom" );

The false in the printstream constructor turns auto-flushing off. If you want to force a message to be sent you need to flush the buffer via:

	cout.flush();

Q - What do I send between the Client and Server?

What do you want them to do?

CS 596 Client-Server Programming Java Network Q and A