Netty源码分析 - Bootstrap服务端

系列

Netty源码分析 - Bootstrap服务端
Netty源码分析 - Bootstrap客户端
netty源码分析 - ChannelHandler
netty源码分析 - EventLoop类关系
netty源码分析 - register分析
Netty源码分析 - NioEventLoop事件处理
netty源码分析 - accept过程分析
Netty源码分析 - ByteBuf
Netty源码分析 - 粘包和拆包问题

开篇

• 本文基于netty-4.1.8.Final版本进行分析，主要是分析Netty Server初始化过程。
• 建议先参考Netty源码分析 - Bootstrap客户端文章。
• 理解NioServerSocketChannel的初始化和注册流程。
• 理解ServerBootstrap的bind流程，理解bossGroup与workerGroup的关系。
  
  

Netty Server案例

public final class DiscardServer {

    static final boolean SSL = System.getProperty("ssl") != null;
    static final int PORT = Integer.parseInt(System.getProperty("port", "8009"));

    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;
        }
        // 父bossGroup
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        // 子workerGroup
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            // 创建ServerBootstrap
            ServerBootstrap b = new ServerBootstrap();
            // 绑定group
            b.group(bossGroup, workerGroup)
              // 绑定channel
             .channel(NioServerSocketChannel.class)
              // 绑定父handler
             .handler(new LoggingHandler(LogLevel.INFO))
              // 绑定子handler
             .childHandler(new ChannelInitializer() {
                 @Override
                 public void initChannel(SocketChannel ch) {
                      // 添加handler到ChannelPipeline
                     ChannelPipeline p = ch.pipeline();
                     if (sslCtx != null) {
                         p.addLast(sslCtx.newHandler(ch.alloc()));
                     }
                     p.addLast(new DiscardServerHandler());
                 }
             });

            // Bind and start to accept incoming connections.
            ChannelFuture f = b.bind(PORT).sync();

            // Wait until the server socket is closed.
            // In this example, this does not happen, but you can do that to gracefully
            // shut down your server.
            f.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }
}

ServerBootstrap

ServerBootstrap

public class ServerBootstrap extends AbstractBootstrap {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(ServerBootstrap.class);

    private final Map, Object> childOptions = new LinkedHashMap, Object>();
    private final Map, Object> childAttrs = new LinkedHashMap, Object>();
    private final ServerBootstrapConfig config = new ServerBootstrapConfig(this);
    private volatile EventLoopGroup childGroup;
    private volatile ChannelHandler childHandler;

    public ServerBootstrap() { }

    public ServerBootstrap group(EventLoopGroup group) {
        return group(group, group);
    }

    public ServerBootstrap group(EventLoopGroup parentGroup, EventLoopGroup childGroup) {
        super.group(parentGroup);
        this.childGroup = childGroup;
        return this;
    }

    public  ServerBootstrap childOption(ChannelOption childOption, T value) {
        if (value == null) {
            synchronized (childOptions) {
                childOptions.remove(childOption);
            }
        } else {
            synchronized (childOptions) {
                childOptions.put(childOption, value);
            }
        }
        return this;
    }

    public  ServerBootstrap childAttr(AttributeKey childKey, T value) {
        if (value == null) {
            childAttrs.remove(childKey);
        } else {
            childAttrs.put(childKey, value);
        }
        return this;
    }

    public ServerBootstrap childHandler(ChannelHandler childHandler) {
        this.childHandler = childHandler;
        return this;
    }

    @Override
    void init(Channel channel) throws Exception {
        final Map, Object> options = options0();
        synchronized (options) {
            setChannelOptions(channel, options, logger);
        }

        final Map, Object> attrs = attrs0();
        synchronized (attrs) {
            for (Entry, Object> e: attrs.entrySet()) {
                @SuppressWarnings("unchecked")
                AttributeKey