netty学习8：NioSocketChannel源码分析

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我是靠谱客的博主激情万宝路，最近开发中收集的这篇文章主要介绍netty学习8：NioSocketChannel源码分析，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

NioSocketChannel就是nio中的SocketChannel的封装，所以它肯定会提供了SocketChannel对象的创建、连接、端口绑定、关闭等操作,netty客户端和服务端都有用到这个对象。

public NioSocketChannel() {//类被反射加载的时候调用该无参构造函数
        this(DEFAULT_SELECTOR_PROVIDER);
    }

public NioSocketChannel(SelectorProvider provider) {
        this(newSocket(provider));//创建SocketChannel并赋值
    }

public NioSocketChannel(SocketChannel socket) {
        this(null, socket);
    }

public NioSocketChannel(Channel parent, SocketChannel socket) {
        super(parent, socket);
        config = new NioSocketChannelConfig(this, socket.socket());
    }



//创建SocketChannel客户端channel
    private static SocketChannel newSocket(SelectorProvider provider) {
        try {
            //创建nio的SocketChannel对象
            return provider.openSocketChannel();
        } catch (IOException e) {
            throw new ChannelException("Failed to open a socket.", e);
        }
    }

//客户端跟服务端建立连接
    @Override
    protected boolean doConnect(SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
        if (localAddress != null) {
            doBind0(localAddress);//绑定地址
        }

        boolean success = false;
        try {
            boolean connected = SocketUtils.connect(javaChannel(), remoteAddress);//跟远程地址建立连接
            if (!connected) {
                selectionKey().interestOps(SelectionKey.OP_CONNECT);
            }
            success = true;
            return connected;
        } finally {
            if (!success) {
                doClose();
            }
        }
    }

private void doBind0(SocketAddress localAddress) throws Exception {
        if (PlatformDependent.javaVersion() >= 7) {
            SocketUtils.bind(javaChannel(), localAddress);//绑定地址
        } else {
            SocketUtils.bind(javaChannel().socket(), localAddress);
        }
    }





public abstract class AbstractNioChannel extends AbstractChannel {

protected AbstractNioChannel(Channel parent, SelectableChannel ch, int readInterestOp) {
        super(parent);
        this.ch = ch;//在io.netty.channel.socket.nio.NioServerSocketChannel.doReadMessages中调用 在NioSocketChannel实例化时候也会调用
        this.readInterestOp = readInterestOp;//bossGroup是NioServerSocketChannel写死OP_ACCEPT事件 workgroup是AbstractNioByteChannel写死OP_READ事件
        try {
            ch.configureBlocking(false);//设置为非阻塞
        } catch (IOException e) {
            try {
                ch.close();
            } catch (IOException e2) {
                logger.warn(
                            "Failed to close a partially initialized socket.", e2);
            }

            throw new ChannelException("Failed to enter non-blocking mode.", e);
        }
    }
}

总结就是：

1、netty客户端创建SocketChannel

2、netty客户端建立远程连接

3、netty服务端获取到客户端SocketChannel之后包装成NioSocketChannel对象也会用到相关构造函数