一段关于java NIO server端接受客户端socket连接；演示了关于channel,selector等组件的整合使用

public class ReactorDemo {

    public static void main(String[] args) throws IOException {
        ServerSocketChannel ssc = ServerSocketChannel.open();//管道型ServerSocket
        ssc.socket().bind(new InetSocketAddress("127.0.0.1", 8089));
        ssc.configureBlocking(false);//设置非阻塞
        System.out.println(" NIO single server started, listening on :" + ssc.getLocalAddress());
        Selector selector = Selector.open();
        ssc.register(selector, SelectionKey.OP_ACCEPT);//在建立好的管道上，注册关心的事件 就绪
        while(true) {
            selector.select();
            Set<SelectionKey> keys = selector.selectedKeys();
            Iterator<SelectionKey> it = keys.iterator();
            while(it.hasNext()) {
                SelectionKey key = it.next();
                it.remove();//处理的事件，必须删除
                handle(key);
            }
        }
    }
    private static void handle(SelectionKey key) throws IOException {
        if(key.isAcceptable()) {//测试通道是否准备好接受新的套接字连接。
            System.out.println("accept occur...");
            ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
            SocketChannel sc = ssc.accept();
            sc.configureBlocking(false);//设置非阻塞
            sc.register(key.selector(), SelectionKey.OP_READ );//在建立好的管道上，注册关心的事件 可读
        } else if (key.isReadable()) { //测试通道是否可以读取
            System.out.println("readable occur ...");
            SocketChannel sc = null;
            sc = (SocketChannel)key.channel();
            ByteBuffer buffer = ByteBuffer.allocate(512);
            buffer.clear();
            int len = sc.read(buffer);
            if(len != -1) {
                System.out.println("[" +Thread.currentThread().getName()+"] recv :"+ new String(buffer.array(), 0, len));
            }
            ByteBuffer bufferToWrite = ByteBuffer.wrap("HelloClient".getBytes());
            sc.write(bufferToWrite);
        }else if(key.isWritable()){
            System.out.println("write able occur...");
        }
    }
}