//
// DateServer.java
// Acts as a server to give its local Date and Time.
// Client must connect on the correct port.
// Server closes the connection after send.
//
// Give the port number as a command line argument:
// e.g. java DateServer 4567
//
import java.io.*;
import java.net.*;
import java.util.Date;
public class DateServer {
public final static int DEFAULT_PORT = 3456; // constants
public final static int qLen = 5;
private static ServerSocket listenSocket = null;
private static OutputStreamWriter osw = null;
public void DateServer() {} // Empty constructor!
public static void main( String[] args) throws IOException {
int portNum = DEFAULT_PORT;
if( args.length != 0) {
portNum = Integer.parseInt( args[ 0]);
// put some test here to allow for port number not in range
}
try { // listen for clients and queue those that can’t be handled yet!
listenSocket = new ServerSocket( portNum, qLen);
}
catch( BindException e) {
System.err.println("Could not bind to port: " + portNum);
System.err.println( "\tIs it already in use?");
System.err.println( "\tIs it a reserved port number?");
System.exit(1);
}
while( true) { // loop forever accepting clients from the queue
Socket clientSocket = null;
try { // talk to the client on a new socket
clientSocket = listenSocket.accept();
osw = new OutputStreamWriter( clientSocket.getOutputStream());
// Might need to end previous line with , "US-ASCII"); or // "UTF-8");!
Date date = new Date();
// Why do we need to convert the date to a String?
osw.write( date.toString()); // do we need + "\r\n");?
osw.flush(); // make sure date got sent from the buffer!
clientSocket.close();
}
catch( IOException ioE) {
System.err.println( "Connection error, maybe the client died!");
}
finally { // to trap any other errors!!
try {
if( clientSocket != null) clientSocket.close();
}
catch( IOException ioE) {}
} // end of finally
} // while forever waiting for a client connection
} // main
} // class DateServer