quoteclient.java

21天学通java的示例程序源代码

package com.wrox.quote;

import java.io.*;
import java.net.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;

public class QuoteClient
{
    // Define my favorite default port. Just look at a phone ;)
    private static final int DEFAULT_PORT = 7236;

    // The buffer to hold the incoming data
    private static ByteBuffer buffer = ByteBuffer.allocateDirect( 1024 );

    /**
     * Asks for a quote
     */
    private static void requestQuote( String host,
                                      int port ) throws IOException
    {

        InetSocketAddress socketAddress = new InetSocketAddress(
                                              InetAddress.getByName( host ), 
                                              port );
        SocketChannel socketChannel = null;

        try
        {
            // Connect to the Quote Server
            socketChannel = SocketChannel.open();
            socketChannel.connect( socketAddress );

            // As recommended by the API docs, clear the buffer before
            // a channel read or put operation to fill the buffer.
            buffer.clear();
            socketChannel.read( buffer );

            // After a read or put operation, the flip() call resets the
            // limit, position and any marks such that the buffer's data
            // is ready for use. See the API docs for more details.
            buffer.flip();
            Charset charset = Charset.forName( "US-ASCII" );
            CharsetDecoder decoder = charset.newDecoder();
            CharBuffer charBuffer = decoder.decode( buffer );
            System.out.print( charBuffer );
        }
        finally
        {
            if( socketChannel != null )
            {
                socketChannel.close();
            }
        }
    }

    public static void main(String[] args)
    {

        if( args.length == 0 )
        {
            System.err.println( "Syntax: java QuoteClient " +  
                                "[QuoteServer host] [port number " +
                                "to request a connection on.]" );
            System.exit( 1 );
        }

        // Get the host from the commandline.
        String host = args[0];
        int port = DEFAULT_PORT;

        // Check to see if a port number was supplied.
        if( args.length == 2 )
        {
            try
            {
                port = Integer.parseInt( args[1] );
            }
            catch( NumberFormatException nfe )
            {
                System.err.println( "Syntax: java QuoteClient " +  
                                    "[QuoteServer host] [port number " +
                                    "to request a connection on.]" );
                System.exit( 1 );
            }
        }

        // Make a request.
        try
        {
            QuoteClient.requestQuote( host, port );
        }
        catch( Exception e )
        {
            System.err.println( "Error: " + e );
        }
    }
}