标签：selector accept blocking 调用 try led rri point efault
一 问题
1. 服务端socket在哪里初始化
2. 在哪里accept连接
二 Netty启动Channel过程
1. 创建服务端Channel
2. 初始化服务端Channel
3.注册selector
4.端口绑定
三 Netty启动Channel过程： 创建服务端Channel
1. AbstractBootstrap.bind() //用户代码入口
2. AbstractBootstrap.initAndRegister() //初始化并注册
3. newChannel() //创建服务端channel
newChannel()只是ChannelFactory接口的fang方法，具体实现是掉的哪个实现类
查看 ServerBootstrap 对象，会发现 ServerBootstrap 制定了了NioServerSocketChannel.class这个channel
进入channel()方法，会发现返回了一个 ReflectiveChannelFactory 的ChannelFactory
public B channel(Class<? extends C> channelClass) { if (channelClass == null) { throw new NullPointerException("channelClass"); } return channelFactory(new ReflectiveChannelFactory<C>(channelClass)); }
查看 ReflectiveChannelFactory.newChannel() ,原来newChannel()只是用反射的方法创建了一个NioServerSocketChannel类型的Channel对象
@Override public T newChannel() { try { return clazz.newInstance(); } catch (Throwable t) { throw new ChannelException("Unable to create Channel from class " + clazz, t); } }
四 NioServerSocketChannel构造函数大纲
1. newSocket() //通过JDK底层来创建jdk channel
2.NioServerSocketChannelConfig() //tcp参数配置类
3.AbstractNioChannel.configureBlocking(false) //设置为非阻塞模式
4.AbstractChannel.AbstractChannel() //创建id，unsafe，pipeline
五 NioServerSocketChannel创建流程
1.无参构造方法中调用newSocket()方法并传入一个DEFAULT_SELECTOR_PROVIDER，DEFAULT_SELECTOR_PROVIDER=SelectorProvider.provider()，newSocket()方法调用jdk的SelectorProvider.provider().openServerSocketChannel() 创建一个jdk底层的一个 ServerSocketChannel
public NioServerSocketChannel() { this(newSocket(DEFAULT_SELECTOR_PROVIDER)); }
private static ServerSocketChannel newSocket(SelectorProvider provider) { try { return provider.openServerSocketChannel(); } catch (IOException e) { throw new ChannelException( "Failed to open a server socket.", e); } }
2.创建一个 NioServerSocketChannelConfig 配置类
public NioServerSocketChannel(ServerSocketChannel channel) { super(null, channel, SelectionKey.OP_ACCEPT); config = new NioServerSocketChannelConfig(this, javaChannel().socket()); }
3.调用父类的 AbstractNioChannel 构造器，设置配置configureBlocking为false，表明是一个非阻塞的IO模式
protected AbstractNioChannel(Channel parent, SelectableChannel ch, int readInterestOp) { super(parent); this.ch = ch; this.readInterestOp = readInterestOp; try { ch.configureBlocking(false); } catch (IOException e) { try { ch.close(); } catch (IOException e2) { if (logger.isWarnEnabled()) { logger.warn( "Failed to close a partially initialized socket.", e2); } } throw new ChannelException("Failed to enter non-blocking mode.", e); } }
4. 再调用父类AbstractChannel构造器，设置id， unsafe，pipeline属性
protected AbstractChannel(Channel parent) { this.parent = parent; id = DefaultChannelId.newInstance(); unsafe = newUnsafe(); pipeline = new DefaultChannelPipeline(this); }
到这里，服务端Channel创建完成
标签：selector accept blocking 调用 try led rri point efault
原文地址：https://www.cnblogs.com/programmlover/p/11924247.html
