Java 7 new features - 5. NIO2 : C. Blocking TCP server/client example

<< Previous

Table of Categories

Next>>

---

Java 7 introduces a new interface - NetworkChannel that provides common methods to all network channel classes and a new SocketOption interface and StandardSocketOptions class. Please check the following exmaple. To demonstrate how ByteBuffer works, I just set buffer size as 2.

Blocking TCP Server

 
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.StandardSocketOptions;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;

public class BlockingTcpServer
{
    public static void main(String[] args)
    {
        final int SERVER_PORT = 9001;
        final String SERVER_IP = "127.0.0.1";
        
        ByteBuffer incomingBuffer = ByteBuffer.allocateDirect(2);
        ByteBuffer outgoingBuffer = ByteBuffer.wrap("World".getBytes());
        Charset charset = Charset.defaultCharset();
        CharsetDecoder decoder = charset.newDecoder();
        String requestMsg = "";
        
        try (ServerSocketChannel serverSocketChannel = ServerSocketChannel.open())
        {
            if (serverSocketChannel.isOpen())
            {
                serverSocketChannel.configureBlocking(true);
                
                //set options
                serverSocketChannel.setOption(StandardSocketOptions.SO_RCVBUF, 1024);
                serverSocketChannel.setOption(StandardSocketOptions.SO_REUSEADDR, true);
                
                //bind the server socket channel to local address
                serverSocketChannel.bind(new InetSocketAddress(SERVER_IP, SERVER_PORT));
                while (true)
                {
                    try (SocketChannel socketChannel = serverSocketChannel.accept())
                    {
                        
                        while (socketChannel.read(incomingBuffer) != -1)
                        {
                            incomingBuffer.flip();
                            String msgReceived = decoder.decode(incomingBuffer).toString();
                            System.out.println("Msg received in this loop : " + msgReceived);
                            requestMsg = requestMsg + msgReceived;
                            if (incomingBuffer.hasRemaining())
                            {
                                incomingBuffer.compact();
                            }
                            else
                            {
                                incomingBuffer.clear();
                            }
                        }
                        System.out.println("Request from " + socketChannel.getRemoteAddress() 
                                                           + " : " + requestMsg);
                        socketChannel.write(outgoingBuffer);
                        outgoingBuffer.flip();
                    }
                    catch (IOException ex)
                    {
                        ex.printStackTrace();
                    }
                }
            }
            else
            {
                System.out.println("The server socket channel cannot be opened!");
            }
        }
        catch (IOException ex)
        {
            System.err.println(ex);
        }
    }
}

Blocking TCP Client

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.StandardSocketOptions;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;

public class BlockingTcpClient
{
    public static void main(String[] args)
        throws IOException
    {
        final int SERVER_PORT = 9001;
        final String SERVER_IP = "127.0.0.1";
        ByteBuffer receivingBuffer = ByteBuffer.allocateDirect(2);
        ByteBuffer sendingBuffer = ByteBuffer.wrap("Hello".getBytes());
        Charset charset = Charset.defaultCharset();
        CharsetDecoder decoder = charset.newDecoder();
        String responseMsg = "";
        //create a new socket channel
        try (SocketChannel socketChannel = SocketChannel.open())
        {
            if (socketChannel.isOpen())
            {
                //set the blocking mode
                socketChannel.configureBlocking(true);
                
                socketChannel.setOption(StandardSocketOptions.SO_SNDBUF, 1024);
                socketChannel.setOption(StandardSocketOptions.SO_RCVBUF, 1024);
                socketChannel.setOption(StandardSocketOptions.SO_LINGER, 10);
            
                //establish channel connection
                socketChannel.connect(new InetSocketAddress(SERVER_IP, SERVER_PORT));
                if (socketChannel.isConnected())
                {
                    //sending data
                    socketChannel.write(sendingBuffer);
                    socketChannel.shutdownOutput();
                    //receving data
                    while (socketChannel.read(receivingBuffer) != -1)
                    {
                        receivingBuffer.flip();
                        String msgReceived = decoder.decode(receivingBuffer).toString();
                        System.out.println("Msg received in this loop : " + msgReceived);
                        responseMsg = responseMsg + msgReceived; 
                        if (receivingBuffer.hasRemaining())
                        {
                            receivingBuffer.compact();
                        }
                        else
                        {
                            receivingBuffer.clear();
                        }
                    }
                   
                    System.out.println("Response from server : "+ responseMsg);
                }
                else
                {
                    System.out.println("The connection cannot be established!");
                }
            }
            else
            {
                System.out.println("The socket channel cannot be opened!");
            }
        }
        catch (IOException ex)
        {
            System.err.println(ex);
        }


    }
}