【轉載】Java非同步通訊收藏

   //伺服器端監聽執行緒
    while (true) {
                .............
                Socket clientSocket;
                clientSocket = socket.accept(); //取得客戶請求Socket，如果沒有//客戶請求連線，執行緒在此處阻塞
                //用取得的Socket構造輸入輸出流
                PrintStream s = new PrintStream(new
                BufferedOutputStream(clientSocket.getOutputStream(),
                1024), false);
                BufferedReader is = new BufferedReader(new
                InputStreamReader(clientSocket.getInputStream()));
                //建立客戶會話執行緒,進行輸入輸出控制，為同步機制
                new ClientSession();
                .......
                 }

  ............
   clientSocket = new Socket(HOSTNAME, LISTENPORT);//連線伺服器套接字
   //用取得的Socket構造輸入輸出流
   PrintStream s = new PrintStream(new
                BufferedOutputStream(clientSocket.getOutputStream(),
                1024), false);
                BufferedReader is = new BufferedReader(new
                InputStreamReader(clientSocket.getInputStream()));
   //進行輸入輸出控制
    .......

public class NBlockingServer {
    int port = 8000;
    int BUFFERSIZE = 1024;
    Selector selector = null;
    ServerSocketChannel serverChannel = null;
    HashMap clientChannelMap = null;//用來存放每一個客戶連線對應的套接字和通道

    public NBlockingServer( int port ) {
        this.clientChannelMap = new HashMap();
        this.port = port;
    }

    public void initialize() throws IOException {
      //初始化，分別例項化一個選擇器，一個伺服器端可選擇通道
      this.selector = Selector.open();
      this.serverChannel = ServerSocketChannel.open();
      this.serverChannel.configureBlocking(false);
      InetAddress localhost = InetAddress.getLocalHost();
      InetSocketAddress isa = new InetSocketAddress(localhost, this.port );
      this.serverChannel.socket().bind(isa);//將該套接字繫結到伺服器某一可用埠
    }
    //結束時釋放資源
    public void finalize() throws IOException {
        this.serverChannel.close();
        this.selector.close();
    }
    //將讀入位元組緩衝的資訊解碼
    public String decode( ByteBuffer byteBuffer ) throws
CharacterCodingException {
        Charset charset = Charset.forName( "ISO-8859-1" );
        CharsetDecoder decoder = charset.newDecoder();
        CharBuffer charBuffer = decoder.decode( byteBuffer );
        String result = charBuffer.toString();
        return result;
    }
    //監聽埠，當通道準備好時進行相應操作
    public void portListening() throws IOException, InterruptedException {
      //伺服器端通道註冊OP_ACCEPT事件
      SelectionKey acceptKey =this.serverChannel.register( this.selector,
                                           SelectionKey.OP_ACCEPT );
        //當有已註冊的事件發生時,select()返回值將大於0
        while (acceptKey.selector().select() > 0 ) {
            System.out.println("event happened");
            //取得所有已經準備好的所有選擇鍵
            Set readyKeys = this.selector.selectedKeys();
            //使用迭代器對選擇鍵進行輪詢
            Iterator i = readyKeys.iterator();
            while (i.hasNext()) {
                SelectionKey key = (SelectionKey)i.next();
                i.remove();//刪除當前將要處理的選擇鍵
                if ( key.isAcceptable() ) {//如果是有客戶端連線請求
                    System.out.println("more client connect in!");
                    ServerSocketChannel nextReady =
                        (ServerSocketChannel)key.channel();
                    //獲取客戶端套接字
                    Socket s = nextReady.accept();
                    //設定對應的通道為非同步方式並註冊感興趣事件
                    s.getChannel().configureBlocking( false );
                    SelectionKey readWriteKey =
                        s.getChannel().register( this.selector,
                            SelectionKey.OP_READ|SelectionKey.OP_WRITE  );
                    //將註冊的事件與該套接字聯絡起來
readWriteKey.attach( s );
//將當前建立連線的客戶端套接字及對應的通道存放在雜湊表//clientChannelMap中
                    this.clientChannelMap.put( s, new
ClientChInstance( s.getChannel() ) );
                    }
                else if ( key.isReadable() ) {//如果是通道讀準備好事件
                    System.out.println("Readable");
                    //取得選擇鍵對應的通道和套接字
                    SelectableChannel nextReady =
                        (SelectableChannel) key.channel();
                    Socket socket = (Socket) key.attachment();
                    //處理該事件，處理方法已封裝在類ClientChInstance中
                    this.readFromChannel( socket.getChannel(),
                    (ClientChInstance)
this.clientChannelMap.get( socket ) );
                }
                else if ( key.isWritable() ) {//如果是通道寫準備好事件
                    System.out.println("writeable");
                    //取得套接字後處理，方法同上
                    Socket socket = (Socket) key.attachment();
                    SocketChannel channel = (SocketChannel)
socket.getChannel();
                    this.writeToChannel( channel,"This is from server!");
                }
            }
        }
    }
    //對通道的寫操作
    public void writeToChannel( SocketChannel channel, String message )
throws IOException {
        ByteBuffer buf = ByteBuffer.wrap( message.getBytes()  );
        int nbytes = channel.write( buf );
    }
     //對通道的讀操作
    public void readFromChannel( SocketChannel channel, ClientChInstance clientInstance )
    throws IOException, InterruptedException {
        ByteBuffer byteBuffer = ByteBuffer.allocate( BUFFERSIZE );
        int nbytes = channel.read( byteBuffer );