public static void main(String[] args) throws IOException {  
        // TODO Auto-generated method stub  
        // 打开socket通道  
        SocketChannel socketChannel = SocketChannel.open();  
        // 设置为非阻塞方式  
        socketChannel.configureBlocking(false);  
        // 打开选择器  
        Selector selector = Selector.open();  
        // 注册连接服务端socket动作  
        socketChannel.register(selector, SelectionKey.OP_CONNECT);  
        // 连接  
        socketChannel.connect(SERVER_ADDRESS);  
        // 分配缓冲区大小内存  
          
        Set<SelectionKey> selectionKeys;  
        Iterator<SelectionKey> iterator;  
        SelectionKey selectionKey;  
        SocketChannel client = null;  
        String receiveText;  
        String sendText;  
        int count=0;  
        int limit = 10;
        while (true) {  
        	limit--;
        	
            //选择一组键，其相应的通道已为 I/O 操作准备就绪。  
            //此方法执行处于阻塞模式的选择操作。  
            selector.select();  
            //返回此选择器的已选择键集。  
            selectionKeys = selector.selectedKeys();  
            //System.out.println(selectionKeys.size());  
            iterator = selectionKeys.iterator();  
            while (iterator.hasNext()) {  
                selectionKey = iterator.next();  
                if (selectionKey.isConnectable()) {  
                    System.out.println("client connect");  
                    client = (SocketChannel) selectionKey.channel();  
                    // 判断此通道上是否正在进行连接操作。  
                    // 完成套接字通道的连接过程。  
                    if (client.isConnectionPending()) {  
                        client.finishConnect();  
                        System.out.println("完成连接!");  
                        sendbuffer.clear();  
                        sendbuffer.put("Hello,Server".getBytes());  
                        sendbuffer.flip();  
                        client.write(sendbuffer);  
                    }  
                    client.register(selector, SelectionKey.OP_READ);  
                } else if (selectionKey.isReadable()) {  
                    client = (SocketChannel) selectionKey.channel();  
                    //将缓冲区清空以备下次读取  
                    receivebuffer.clear();  
                    //读取服务器发送来的数据到缓冲区中  
                    count=client.read(receivebuffer);  
                    if(count>0){  
                    	//System.out.println("array is :"+receivebuffer.hasArray());
                        receiveText = new String( receivebuffer.array(),0,count);  
                        System.out.println("客户端接受服务器端数据--:"+receiveText);  
                        client.register(selector, SelectionKey.OP_WRITE);  
                    }  
  
                } else if (selectionKey.isWritable()) {  
                    sendbuffer.clear();  
                    client = (SocketChannel) selectionKey.channel();  
                    sendText = " message from client--" + (flag++);  
                    sendbuffer.put(sendText.getBytes());  
                     //将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位  
                    sendbuffer.flip();  
                    client.write(sendbuffer);  
                    System.out.println("客户端向服务器端发送数据--："+sendText);  
                    client.register(selector, SelectionKey.OP_READ);  
                }  
            }  
            
            //System.out.println("selectionKeys.size() = " + selectionKeys.size());
            selectionKeys.clear();  
            if (limit==0) {
            	client.close();
        		break;
        	}
        }  
    }