Netty原始碼分析（一）：Netty總覽

貳級天災發表於2019-03-23

作為當前最流行的網路通訊框架，Netty在網際網路領域大放異彩，本系列將詳細介紹Netty(4.1.22.Final)。

程式碼事例

服務端

public final class EchoServer {
    // 從啟動引數判斷是否使用ssl
    static final boolean SSL = System.getProperty("ssl") != null;
    // 獲取埠（預設8007）
    static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));

    public static void main(String[] args) throws Exception {
        // 配置SSL
        final SslContext sslCtx;
        if (SSL) {
            SelfSignedCertificate ssc = new SelfSignedCertificate();
            sslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey()).build();
        } else {
            sslCtx = null;
        }
        // 配置伺服器
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline p = ch.pipeline();
                            if (sslCtx != null) {
                                p.addLast(sslCtx.newHandler(ch.alloc()));
                            }
                            // 新增一個自定義的handler
                            p.addLast(new EchoServerHandler());
                        }
                    });
            // 啟動伺服器
            ChannelFuture f = b.bind(PORT).sync();
            // 等待至連線斷開
            f.channel().closeFuture().sync();
        } finally {
            // 關閉伺服器資源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}
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客戶端

public final class EchoClient {
    // 獲取是否使用ssl
    static final boolean SSL = System.getProperty("ssl") != null;
    // 獲取服配置的伺服器地址(預設本地)
    static final String HOST = System.getProperty("host", "127.0.0.1");
    // 獲取埠（預設8007）
    static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));
    // 首次傳送訊息的大小
    static final int SIZE = Integer.parseInt(System.getProperty("size", "256"));

    public static void main(String[] args) throws Exception {
        // 配置SSL
        final SslContext sslCtx;
        if (SSL) {
            sslCtx = SslContextBuilder.forClient()
                    .trustManager(InsecureTrustManagerFactory.INSTANCE).build();
        } else {
            sslCtx = null;
        }
        // 配置客戶端
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    // 禁用Nagle演算法
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline p = ch.pipeline();
                            if (sslCtx != null) {
                                p.addLast(sslCtx.newHandler(ch.alloc(), HOST, PORT));
                            }
                            //p.addLast(new LoggingHandler(LogLevel.INFO));
                            p.addLast(new EchoClientHandler());
                        }
                    });
            // 啟動客戶端
            ChannelFuture f = b.connect(HOST, PORT).sync();
            //等待至連線斷開
            f.channel().closeFuture().sync();
        } finally {
            // 關閉客戶端資源
            group.shutdownGracefully();
        }
    }
}
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