一 接口

@SPI("netty")
public interface Transporter {

    /**
     * Bind a server.
     *
     * @param url     server url
     * @param handler
     * @return server
     * @throws RemotingException
     * @see com.alibaba.dubbo.remoting.Transporters#bind(URL, ChannelHandler...)
     */
    @Adaptive({Constants.SERVER_KEY, Constants.TRANSPORTER_KEY})
    Server bind(URL url, ChannelHandler handler) throws RemotingException;

    /**
     * Connect to a server.
     *
     * @param url     server url
     * @param handler
     * @return client
     * @throws RemotingException
     * @see com.alibaba.dubbo.remoting.Transporters#connect(URL, ChannelHandler...)
     */
    @Adaptive({Constants.CLIENT_KEY, Constants.TRANSPORTER_KEY})
    Client connect(URL url, ChannelHandler handler) throws RemotingException;

}

二 Transporter$Adaptive

package com.alibaba.dubbo.remoting;

import com.alibaba.dubbo.common.extension.ExtensionLoader;

public class Transporter$Adaptive implements com.alibaba.dubbo.remoting.Transporter {
    public com.alibaba.dubbo.remoting.Client connect(com.alibaba.dubbo.common.URL arg0, com.alibaba.dubbo.remoting.ChannelHandler arg1) throws com.alibaba.dubbo.remoting.RemotingException {
        if (arg0 == null) throw new IllegalArgumentException("url == null");
        com.alibaba.dubbo.common.URL url = arg0;
        String extName = url.getParameter("client", url.getParameter("transporter", "netty"));
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.remoting.Transporter) name from url(" + url.toString() + ") use keys([client, transporter])");
        com.alibaba.dubbo.remoting.Transporter extension = (com.alibaba.dubbo.remoting.Transporter) ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.remoting.Transporter.class).getExtension(extName);
        return extension.connect(arg0, arg1);
    }

    public com.alibaba.dubbo.remoting.Server bind(com.alibaba.dubbo.common.URL arg0, com.alibaba.dubbo.remoting.ChannelHandler arg1) throws com.alibaba.dubbo.remoting.RemotingException {
        if (arg0 == null) throw new IllegalArgumentException("url == null");
        com.alibaba.dubbo.common.URL url = arg0;
        String extName = url.getParameter("server", url.getParameter("transporter", "netty"));
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.remoting.Transporter) name from url(" + url.toString() + ") use keys([server, transporter])");
        com.alibaba.dubbo.remoting.Transporter extension = (com.alibaba.dubbo.remoting.Transporter) ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.remoting.Transporter.class).getExtension(extName);
        return extension.bind(arg0, arg1);
    }
}

实现

• SPI指定的默认实现是netty

• 自适应扩展点

  • URL中配置server

  • URL中配置transporter

三 实现

1 NettyTransporter

1.1 生产者服务导出

@Override
    public Server bind(URL url, ChannelHandler listener) throws RemotingException {
        return new NettyServer(url, listener);
    }

// NettyServer.java
public NettyServer(URL url, ChannelHandler handler) throws RemotingException {
        // 调用父类构造方法 回调子类的实现doOpen(...)
        super(url, ChannelHandlers.wrap(handler, ExecutorUtil.setThreadName(url, SERVER_THREAD_POOL_NAME)));
    }

// AbstractServer.java
public AbstractServer(URL url, ChannelHandler handler) throws RemotingException {
        super(url, handler);
        localAddress = getUrl().toInetSocketAddress(); // /192.168.0.11:20880

        String bindIp = getUrl().getParameter(Constants.BIND_IP_KEY, getUrl().getHost()); // 192.168.0.1
        int bindPort = getUrl().getParameter(Constants.BIND_PORT_KEY, getUrl().getPort()); // 20880
        if (url.getParameter(Constants.ANYHOST_KEY, false) || NetUtils.isInvalidLocalHost(bindIp)) {
            bindIp = NetUtils.ANYHOST;
        }
        bindAddress = new InetSocketAddress(bindIp, bindPort);
        this.accepts = url.getParameter(Constants.ACCEPTS_KEY, Constants.DEFAULT_ACCEPTS);
        this.idleTimeout = url.getParameter(Constants.IDLE_TIMEOUT_KEY, Constants.DEFAULT_IDLE_TIMEOUT);
        try {
            this.doOpen(); // 模板方法 实现在子类
            if (logger.isInfoEnabled()) {
                logger.info("Start " + getClass().getSimpleName() + " bind " + getBindAddress() + ", export " + getLocalAddress());
            }
        } catch (Throwable t) {
            throw new RemotingException(url.toInetSocketAddress(), null, "Failed to bind " + getClass().getSimpleName()
                    + " on " + getLocalAddress() + ", cause: " + t.getMessage(), t);
        }
        //fixme replace this with better method
        DataStore dataStore = ExtensionLoader.getExtensionLoader(DataStore.class).getDefaultExtension();
        executor = (ExecutorService) dataStore.get(Constants.EXECUTOR_SERVICE_COMPONENT_KEY, Integer.toString(url.getPort()));
    }

// NettyServer.java
@Override
    protected void doOpen() throws Throwable { // 典型的netty编程
        bootstrap = new ServerBootstrap();

        bossGroup = new NioEventLoopGroup(1, new DefaultThreadFactory("NettyServerBoss", true));
        workerGroup = new NioEventLoopGroup(getUrl().getPositiveParameter(Constants.IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS),
                new DefaultThreadFactory("NettyServerWorker", true));

        final NettyServerHandler nettyServerHandler = new NettyServerHandler(getUrl(), this);
        channels = nettyServerHandler.getChannels();

        bootstrap.group(bossGroup, workerGroup)
                .channel(NioServerSocketChannel.class)
                .childOption(ChannelOption.TCP_NODELAY, Boolean.TRUE)
                .childOption(ChannelOption.SO_REUSEADDR, Boolean.TRUE)
                .childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
                .childHandler(new ChannelInitializer<NioSocketChannel>() {
                    @Override
                    protected void initChannel(NioSocketChannel ch) throws Exception {
                        NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec(), getUrl(), NettyServer.this);
                        ch.pipeline()//.addLast("logging",new LoggingHandler(LogLevel.INFO))//for debug
                                .addLast("decoder", adapter.getDecoder())
                                .addLast("encoder", adapter.getEncoder())
                                .addLast("handler", nettyServerHandler);
                    }
                });
        // bind
        ChannelFuture channelFuture = bootstrap.bind(getBindAddress());
        channelFuture.syncUninterruptibly();
        channel = channelFuture.channel();

    }

Netty编程可以移步

1.2 消费者服务引用

原文地址：http://www.cnblogs.com/miss-u/p/16930838.html