NIO简单客户端与服务端实现代码

public class TestNonBlockingNIO {

    //客户端
    @Test
    public void client() throws IOException{
        // 1. 获取通道
        SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));
        // 2. 切换非阻塞模式
        sChannel.configureBlocking(false);
        // 3. 分配指定大小的缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);
        // 4. 发送数据给服务端
        String str = "hello";
        buf.put((new Date().toString() + "\n" + str).getBytes());
        buf.flip();
        sChannel.write(buf);
        sChannel.shutdownOutput();
        // 5. 关闭通道
        sChannel.close();
    }

    //服务端
    @Test
    public void server() throws IOException{
        //1. 获取通道
        ServerSocketChannel ssChannel = ServerSocketChannel.open();
        //2. 切换非阻塞模式
        ssChannel.configureBlocking(false);
        //3. 绑定连接
        ssChannel.bind(new InetSocketAddress(9898));
        //4. 获取选择器
        Selector selector = Selector.open();
        //5. 将通道注册到选择器上, 并且指定“监听接收事件”
        ssChannel.register(selector, SelectionKey.OP_ACCEPT);
        //6. 轮询式的获取选择器上已经“准备就绪”的事件
        while(selector.select() > 0){
            //7. 获取当前选择器中所有注册的“选择键(已就绪的监听事件)”
            Iterator<SelectionKey> it = selector.selectedKeys().iterator();
            while(it.hasNext()){
                //8. 获取准备“就绪”的是事件
                SelectionKey sk = it.next();
                //9. 判断具体是什么事件准备就绪
                if(sk.isAcceptable()){
                    ServerSocketChannel ss = (ServerSocketChannel) sk.channel();
                    //10. 若“接收就绪”，获取客户端连接
                    SocketChannel sChannel = ss.accept();
                    //11. 切换非阻塞模式
                    sChannel.configureBlocking(false);
                    //12. 将该通道注册到选择器上
                    sChannel.register(selector, SelectionKey.OP_READ);
                }else if(sk.isReadable()){
                    //13. 获取当前选择器上“读就绪”状态的通道
                    SocketChannel sChannel = (SocketChannel) sk.channel();
                    //14. 读取数据
                    ByteBuffer buf = ByteBuffer.allocate(1024);
                    int len = 0;
                    while((len = sChannel.read(buf)) > 0 ){
                        buf.flip();
                        System.out.println(new String(buf.array(), 0, len));
                        buf.clear();
                    }
                    if(len == -1){
                        System.out.println("断开");
                        sChannel.close();
                    }
                }
                //15. 取消选择键 SelectionKey
                it.remove();
            }
        }
    }
}