网络｜Netty｜NIO

 * An HTTP server that sends back the content of the received HTTP request
 * in a pretty plaintext form.
 */
public final class HttpHelloWorldServer {

    static final boolean SSL = System.getProperty("ssl") != null;
    static final int PORT = Integer.parseInt(System.getProperty("port", SSL? "8443" : "8080"));

    public static void main(String[] args) throws Exception {
        // Configure SSL.
        final SslContext sslCtx;
        if (SSL) {
            SelfSignedCertificate ssc = new SelfSignedCertificate();
            sslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey()).build();
        } else {
            sslCtx = null;
        }

        // Configure the server.
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.option(ChannelOption.SO_BACKLOG, 1024);
            b.group(bossGroup, workerGroup)
             .channel(NioServerSocketChannel.class)
             .handler(new LoggingHandler(LogLevel.INFO))
             .childHandler(new HttpHelloWorldServerInitializer(sslCtx));

            Channel ch = b.bind(PORT).sync().channel();

            System.err.println("Open your web browser and navigate to " +
                    (SSL? "https" : "http") + "://127.0.0.1:" + PORT + '/');

            ch.closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

   /**
     * If {@code true} then the {@link Channel} is closed automatically and immediately on write failure.
     * The default value is {@code true}.
     */
    public static final ChannelOption<Boolean> AUTO_CLOSE = valueOf("AUTO_CLOSE");

    public static final ChannelOption<Boolean> SO_BROADCAST = valueOf("SO_BROADCAST");
    public static final ChannelOption<Boolean> SO_KEEPALIVE = valueOf("SO_KEEPALIVE");
    public static final ChannelOption<Integer> SO_SNDBUF = valueOf("SO_SNDBUF");
    public static final ChannelOption<Integer> SO_RCVBUF = valueOf("SO_RCVBUF");
    public static final ChannelOption<Boolean> SO_REUSEADDR = valueOf("SO_REUSEADDR");
    public static final ChannelOption<Integer> SO_LINGER = valueOf("SO_LINGER");
    public static final ChannelOption<Integer> SO_BACKLOG = valueOf("SO_BACKLOG");
    public static final ChannelOption<Integer> SO_TIMEOUT = valueOf("SO_TIMEOUT");

    public static final ChannelOption<Integer> IP_TOS = valueOf("IP_TOS");
    public static final ChannelOption<InetAddress> IP_MULTICAST_ADDR = valueOf("IP_MULTICAST_ADDR");
    public static final ChannelOption<NetworkInterface> IP_MULTICAST_IF = valueOf("IP_MULTICAST_IF");
    public static final ChannelOption<Integer> IP_MULTICAST_TTL = valueOf("IP_MULTICAST_TTL");
    public static final ChannelOption<Boolean> IP_MULTICAST_LOOP_DISABLED = valueOf("IP_MULTICAST_LOOP_DISABLED");

    public static final ChannelOption<Boolean> TCP_NODELAY = valueOf("TCP_NODELAY");

public class HttpHelloWorldServerHandler extends SimpleChannelInboundHandler<HttpObject> {              
    private static final byte[] CONTENT = { 'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd' };    
                                                                                                        
    @Override                                                                                           
    public void channelReadComplete(ChannelHandlerContext ctx) {                                        
        ctx.flush();                                                                                    
    }                                                                                                   
                                                                                                        
    @Override                                                                                           
    public void channelRead0(ChannelHandlerContext ctx, HttpObject msg) {                               
        if (msg instanceof HttpRequest) {                                                               
            HttpRequest req = (HttpRequest) msg;                                                        
                                                                                                        
            boolean keepAlive = HttpUtil.isKeepAlive(req);                                              
            FullHttpResponse response = new DefaultFullHttpResponse(req.protocolVersion(), OK,          
                                                                    Unpooled.wrappedBuffer(CONTENT));   
            response.headers()                                                                          
                    .set(CONTENT_TYPE, TEXT_PLAIN)                                                      
                    .setInt(CONTENT_LENGTH, response.content().readableBytes());                        
                                                                                                        
            if (keepAlive) {                                                                            
                if (!req.protocolVersion().isKeepAliveDefault()) {                                      
                    response.headers().set(CONNECTION, KEEP_ALIVE);                                     
                }                                                                                       
            } else {                                                                                    
                // Tell the client we're going to close the connection.                                 
                response.headers().set(CONNECTION, CLOSE);                                              
            }                                                                                           
                                                                                                        
            ChannelFuture f = ctx.write(response);                                                      
                                                                                                        
            if (!keepAlive) {                                                                           
                f.addListener(ChannelFutureListener.CLOSE);                                             
            }                                                                                           
        }                                                                                               
    }                                                                                                   
                                                                                                        
    @Override                                                                                           
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {                           
        cause.printStackTrace();                                                                        
        ctx.close();                                                                                    
    }                                                                                                   
}