NIO selector多路复用器

public void testScannerServer() throws IOException {
    System.out.println("服务端开启");
    ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();

    // 非阻塞
    serverSocketChannel.configureBlocking(false);

    serverSocketChannel.bind(new InetSocketAddress(8092));

    Selector selector = Selector.open();

    serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

    while (selector.select() > 0) {

        Iterator<SelectionKey> it = selector.selectedKeys().iterator();

        while (it.hasNext()) {
            SelectionKey key = it.next();
            // 为何要remove?
            // https://stackoverflow.com/questions/7132057/why-the-key-should-be-removed-in-selector-selectedkeys-iterator-in-java-ni
            it.remove();
            if (!key.isValid()) {
                System.out.println("链接不可用");
            } else if (key.isAcceptable()) {
                // 新链接
                System.out.println("服务端接受到新链接");
                SocketChannel socketChannel = serverSocketChannel.accept();
                socketChannel.configureBlocking(false); // 非阻塞
                socketChannel.register(selector, SelectionKey.OP_READ); // 注册可读事件
            } else if (key.isReadable()) {
                // 有客户端发送数据
                SocketChannel socketChannel = (SocketChannel) key.channel();
                // 开始读取数据
                System.out.println(new Date().toString());
                ByteBuffer byteBuffer = ByteBuffer.allocate(1024);

                if (socketChannel.read(byteBuffer) == -1) {
                    // -1 说明客户端关闭了写或者直接close
                    System.out.println("客户端关闭链接");
                    // socketChannel.close(); // 其实不须要调用,由于客户端已经关闭, 为了程序稳健性能够开启
                    key.cancel(); // 取消注册
                } else {
                    byteBuffer.flip();
                    System.out.println(new String(byteBuffer.array(), 0, byteBuffer.limit()));
                    byteBuffer.clear();
                }
            }
        }
    }
}
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