SocketChannel在java中实现客户端

public class NonBlockingTCPClient {

    public static void main(String[] args) {

        byte[] data = "hello".getBytes();

        SocketChannel channel = null;

        try {

            // 1. open a socket channel

            channel = SocketChannel.open();

            // adjust to be nonblocking

            channel.configureBlocking(false);

            // 2. init connection to server and repeatedly poll with complete

            // connect() and finishConnect() are nonblocking operation, both return immediately

            if (!channel.connect(new InetSocketAddress(InetAddress.getLocalHost(), 8899))) {

                while (!channel.finishConnect()) {

                    System.out.print(".");

                }

            }

            System.out.println("Connected to server...");

            ByteBuffer writeBuffer = ByteBuffer.wrap(data);

            ByteBuffer readBuffer = ByteBuffer.allocate(data.length);

            int totalBytesReceived = 0;

            int bytesReceived;

            // 3. read and write bytes

            while (totalBytesReceived < data.length) {

                if (writeBuffer.hasRemaining()) {

                    channel.write(writeBuffer);

                }

                if ((bytesReceived = channel.read(readBuffer)) == -1) {

                    throw new SocketException("Connection closed prematurely");

                }

                totalBytesReceived += bytesReceived;

                System.out.print(".");

            }

            System.out.println("Server said: " + new String(readBuffer.array()));

        } catch (IOException e) {

            e.printStackTrace();

        } finally {

            // 4 .close socket channel

            try {

                if (channel != null) {

                    channel.close();

                }

            } catch (IOException e) {

                e.printStackTrace();

            }

        }

    }

}