关于java:netty入门原生jdk-nio写一个服务器

jdk nio 服务器

引言

在学习 netty 之前咱们须要理解 nio，于是我就想分享一下如何用 jdk nio 写一个服务

流程

步骤 1：关上一个服务管道（Channel），并设置非阻塞模式
步骤 2：创立服务
步骤 3：关上一个多路复用器，并注册到 Channel，对 ACCEPT 事件感兴趣
步骤 4：轮询抉择多路复用器，针对不同的复用器进行相干的操作（读、写）

public class NoUseNettyNio {public void serve(int port) throws IOException {

        // 关上一个 ServerSocketChannel
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        // 设置一个 serverSocketChannel 为不阻塞模式，即 nio
        serverSocketChannel.configureBlocking(false);
        // 通过 serverSocketChannel 获取 serverSocket
        ServerSocket serverSocket = serverSocketChannel.socket();
        // 创立一个 server 的网卡地址对象
        InetSocketAddress address = new InetSocketAddress(port);
        // 为 serverSocket 绑定网卡地址
        serverSocket.bind(address);
        // 关上一个 selector（多路复用器）Selector selector = Selector.open();
        // 将多路复用器注册到 serverSocketChannel（管道）上
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        // 创立一个 byteBuffer
        ByteBuffer buffer = ByteBuffer.wrap(("HTTP/1.1 200 OK\r\n" +
                "Content-Type: text/html;charset=UTF-8\r\n").getBytes(StandardCharsets.UTF_8));
        for (; ;) {
            try {
                // 抉择一个通道，此办法是阻塞的，在有一个通道、线程中断或 Selector 的唤醒时，返回
                selector.select();} catch (IOException e) {e.printStackTrace();
                break;
            }
            // 获取的一个 selectKey 汇合，该汇合只能删除不能增加，Set<SelectionKey> selectionKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = selectionKeys.iterator();
            while (iterator.hasNext()) {SelectionKey key = iterator.next();
                iterator.remove();
                try {if (key.isAcceptable()) {ServerSocketChannel server = (ServerSocketChannel) key.channel();
                        SocketChannel client = server.accept();
                        client.configureBlocking(false);
                        client.register(selector,SelectionKey.OP_READ|SelectionKey.OP_WRITE,buffer.duplicate());
                        System.out.println("Accepted connection from"+client);
                    }
                    if(key.isWritable()) {SocketChannel client = (SocketChannel) key.channel();
                        ByteBuffer attachment = (ByteBuffer) key.attachment();
                        while (buffer.hasRemaining()) {System.out.println(attachment.toString());
                            if(client.write(attachment) == 0) {break;}
                        }
                        client.close();}
                } catch (IOException e) {key.channel();
                    try {key.channel().close();} catch (IOException ex) { }
                    e.printStackTrace();}
            }
        }
    }

    public static void main(String[] args) throws IOException {NoUseNettyNio noUseNettyNio = new NoUseNettyNio();
        noUseNettyNio.serve(8910);
    }
}