Java nio Server端示例

public class ServerNio {
    public static void main(String[] args) throws IOException, InterruptedException {

        //打开一个selector

        Selector selector = Selector.open();

        //打开serverSock通道

        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();

        //非阻塞模式

        serverSocketChannel.configureBlocking(false);

        serverSocketChannel.socket().bind(new InetSocketAddress(8099)); // bind address on port

        //向selector注册一个接受客户端事件，如果有客户端想和8099端口建立连接，selector会生成接受连接就绪事件

        SelectionKey selectionKey = serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT, 1);

        try {

            while (true) {

                System.out.println("in while(true)");

                //select 注册的key whose channels are ready for I/O operations

                int count = selector.select();

                System.out.println("select count:" + count);

                //在无限循环中，就绪事件个数大于0时，进入逻辑处理流程

                if (count > 0) {

                    //获取就绪事件key

                    Set<SelectionKey> selectionKeySet = selector.selectedKeys();

                    Iterator<SelectionKey> selectionKeyIterator = selectionKeySet.iterator();

                    //遍历就绪的selectionKey

                    while ((selectionKeyIterator.hasNext())) {

                        SelectionKey key = selectionKeyIterator.next();

                        //先remove掉，防止重复处理

                        selectionKeyIterator.remove();

                        //如果key是建立连接请求

                        if (key.isAcceptable()) {

                            System.out.println("attachment:" + key.attachment());

                            ServerSocketChannel channel = (ServerSocketChannel) key.channel();

                            //如果不处理，那么每次都能select到它,接受请求

                            SocketChannel socketChannel = channel.accept();

                            socketChannel.configureBlocking(false);

                            System.out.println("has accept channel");

                            //                            socketChannel.socket().setSoTimeout(2000);

                            //项selector注册读监控事件，可以考虑注册到另一个selector上去，让当前selector只处理accept

                            socketChannel.register(selector, SelectionKey.OP_READ);

                        } else if (key.isReadable()) {

                            SocketChannel sc = (SocketChannel) key.channel();

                            if (!sc.isOpen()) {

                                System.out.println("in continue");

                                continue;

                            }

                            //开辟4个byte空间

                            ByteBuffer byteBuffer = ByteBuffer.allocate(4);

                            byteBuffer.clear();

                            //从sc中读取byte到buffer中

                            int bytesRead = sc.read(byteBuffer);

                            //断开连接了，-1就是socket关闭的意思

                            if (bytesRead == -1) {

                                sc.close();

                                System.out.println("client is out");

                                continue;

                            }

                            System.out.println("读取的byte个数:" + bytesRead);

                            if (bytesRead > 0) {

                                //切换为读模式

                                byteBuffer.flip();

                                //由于传输的是一个int，这里尝试将4个byte转回int

                                int value = 0;

                                value = value | ((byteBuffer.get(0) & 0xFF) << 24);

                                value = value | ((byteBuffer.get(1) & 0xFF) << 16);

                                value = value | ((byteBuffer.get(2) & 0xFF) << 8);

                                value = value | ((byteBuffer.get(3) & 0xff));

                                //读取到的值

                                System.out.println("transport value:int:" + value);

                            }

                            //                            sc.register(selector, SelectionKey.OP_WRITE);

                        } else if (key.isWritable()) {

                            //类似response

                            SocketChannel sc = (SocketChannel) key.channel();

                            ByteBuffer byteBuffer = ByteBuffer.allocate(4);

                            byteBuffer.clear();

                            byteBuffer.putInt(3);

                            sc.write(byteBuffer);

                            //                            sc.register(selector, SelectionKey.OP_READ);

                        }

                    }

                    System.out.println("selectionKeySize：" + selectionKeySet.size());

                }

                Thread.sleep(100);

            }

        } finally {

            Thread.sleep(20000);

            selector.close();

        }

    }

}
巴特西

Java nio Server端示例

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