netty源码分析 之二 transport(bootstrap)

transport 分为两部分  bootstrap channel 

由于channel东西比较多，所以分开两篇来写

AbstractBootstrap

顾名思义，引导累   抽象父类, 定义模板方法

成员变量

private volatile EventLoopGroup group;
    @SuppressWarnings("deprecation")
    private volatile ChannelFactory<? extends C> channelFactory;
    private volatile SocketAddress localAddress;
    private final Map<ChannelOption<?>, Object> options = new LinkedHashMap<ChannelOption<?>, Object>();
    private final Map<AttributeKey<?>, Object> attrs = new LinkedHashMap<AttributeKey<?>, Object>();
    private volatile ChannelHandler handler;

核心方法

bind绑定方法  主要为server端提供的。

initAndRegister    最核心的

ServerBootstrap

多了child设置，主线程处理连接，child处理read到的消息

    private final Map<ChannelOption<?>, Object> childOptions = new LinkedHashMap<ChannelOption<?>, Object>();
    private final Map<AttributeKey<?>, Object> childAttrs = new LinkedHashMap<AttributeKey<?>, Object>();
    private volatile EventLoopGroup childGroup;
    private volatile ChannelHandler childHandler;

看其init方法

ServerBootstrapAcceptor

继承了ChannelHandlerAdapter   主要实现了channelRead  和exceptionCaught  方法， 其主要作用是子线程来处理消息

public void channelRead(ChannelHandlerContext ctx, Object msg) {
            final Channel child = (Channel) msg;

            child.pipeline().addLast(childHandler);

            for (Entry<ChannelOption<?>, Object> e: childOptions) {
                try {
                    if (!child.config().setOption((ChannelOption<Object>) e.getKey(), e.getValue())) {
                        logger.warn("Unknown channel option: " + e);
                    }
                } catch (Throwable t) {
                    logger.warn("Failed to set a channel option: " + child, t);
                }
            }

            for (Entry<AttributeKey<?>, Object> e: childAttrs) {
                child.attr((AttributeKey<Object>) e.getKey()).set(e.getValue());
            }

            try {
                childGroup.register(child).addListener(new ChannelFutureListener() {
                    @Override
                    public void operationComplete(ChannelFuture future) throws Exception {
                        if (!future.isSuccess()) {
                            forceClose(child, future.cause());
                        }
                    }
                });
            } catch (Throwable t) {
                forceClose(child, t);
            }
        }

Bootstrap

看完serverBootstap之后，这个类就比较简单了。。 再看下connect方法

同样init方法

void init(Channel channel) throws Exception {
        ChannelPipeline p = channel.pipeline();
        p.addLast(handler());

        final Map<ChannelOption<?>, Object> options = options();
        synchronized (options) {
            for (Entry<ChannelOption<?>, Object> e: options.entrySet()) {
                try {
                    if (!channel.config().setOption((ChannelOption<Object>) e.getKey(), e.getValue())) {
                        logger.warn("Unknown channel option: " + e);
                    }
                } catch (Throwable t) {
                    logger.warn("Failed to set a channel option: " + channel, t);
                }
            }
        }

        final Map<AttributeKey<?>, Object> attrs = attrs();
        synchronized (attrs) {
            for (Entry<AttributeKey<?>, Object> e: attrs.entrySet()) {
                channel.attr((AttributeKey<Object>) e.getKey()).set(e.getValue());
            }
        }
    }

connect方法也就是

private static void doConnect0(
            final SocketAddress remoteAddress, final SocketAddress localAddress, final ChannelFuture regFuture,
            final ChannelPromise connectPromise) {

        // This method is invoked before channelRegistered() is triggered.  Give user handlers a chance to set up
        // the pipeline in its channelRegistered() implementation.
        final Channel channel = connectPromise.channel();
        channel.eventLoop().execute(new Runnable() {
            @Override
            public void run() {
                if (regFuture.isSuccess()) {
                    if (localAddress == null) {
                        channel.connect(remoteAddress, connectPromise);
                    } else {
                        channel.connect(remoteAddress, localAddress, connectPromise);
                    }
                    connectPromise.addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
                } else {
                    connectPromise.setFailure(regFuture.cause());
                }
            }
        });
    }