标签：close ase log 默认 oca let card map void
不论是NioServerSocketChannel，还是NioSocketChannel，最终都会调用父类AbstractChannel的构造函数，pipeline也在channel被创建的时候被创建。
protected AbstractChannel(Channel parent) {
this.parent = parent;
this.unsafe = this.newUnsafe();
this.pipeline = new DefaultChannelPipeline(this);
}
而这里是创建了一个DefaultChannelPipeline。构造函数会保存传入的channel，并且默认创建两个节点head和tail并将它们构成双向链表的结构。
public DefaultChannelPipeline(AbstractChannel channel) {
if(channel == null) {
throw new NullPointerException("channel");
} else {
this.channel = channel;
this.tail = new DefaultChannelPipeline.TailContext(this);
this.head = new DefaultChannelPipeline.HeadContext(this);
this.head.next = this.tail;
this.tail.prev = this.head;
}
}
而这里的head和tail都是实现了ChannelHeadContext接口，在pipeline中每一个节点都是ChannelHeadContext，ChannelHeadContext实现了AttributeMap, ChannelInboundInvoker, ChannelOutboundInvoker，其中AttributeMap代表ChannelHeadContext可以存储自定义的属性，而ChannelInboundInvoker, ChannelOutboundInvoker则是定义一些事件的触发方法。
public interface ChannelHandlerContext extends AttributeMap, ChannelInboundInvoker, ChannelOutboundInvoker {
// 返回对应的Channel对象
Channel channel();
// 返回对应的EventLoop对象
EventExecutor executor();
// 返回对应的ChannelHandler对象
ChannelHandler handler();
// 该Context对应的Handler是否从pipeline中移除
boolean isRemoved();
/*******************以下的fire方法都是触发对应事件在pipeline中传播*********************/
ChannelHandlerContext fireChannelRegistered();
ChannelHandlerContext fireChannelUnregistered();
ChannelHandlerContext fireChannelActive();
ChannelHandlerContext fireChannelInactive();
ChannelHandlerContext fireExceptionCaught(Throwable cause);
ChannelHandlerContext fireUserEventTriggered(Object evt);
ChannelHandlerContext fireChannelRead(Object msg);
ChannelHandlerContext fireChannelReadComplete();
ChannelHandlerContext fireChannelWritabilityChanged();
ChannelHandlerContext read();
ChannelHandlerContext flush();
// 返回对应的pipeline
ChannelPipeline pipeline();
}
pipeline中的head和tail分别新建是HeadContext和TailContext，仔细看这两个类的源码，发现它们不仅仅是实现ChannelHandlerContext，而且本身还是一个channelHandler，而让人比较意外的是，HeadContext实现的是ChannelOutboundHandler（处理输出字节），TailContext则是ChannelInboundHandler（处理输入字节）。
从HeadContext的源码可以看出，它的很多操作还是依赖于unsafe的。
static final class HeadContext extends AbstractChannelHandlerContext implements ChannelOutboundHandler {
private static final String HEAD_NAME = DefaultChannelPipeline.generateName0(DefaultChannelPipeline.HeadContext.class);
protected final Channel.Unsafe unsafe;
HeadContext(DefaultChannelPipeline pipeline) {
super(pipeline, (EventExecutorGroup)null, HEAD_NAME, false, true);
this.unsafe = pipeline.channel().unsafe();
}
public ChannelHandler handler() {
return this;
}
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
}
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
}
public void bind(ChannelHandlerContext ctx, SocketAddress localAddress, ChannelPromise promise) throws Exception {
this.unsafe.bind(localAddress, promise);
}
public void connect(ChannelHandlerContext ctx, SocketAddress remoteAddress, SocketAddress localAddress, ChannelPromise promise) throws Exception {
this.unsafe.connect(remoteAddress, localAddress, promise);
}
public void disconnect(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
this.unsafe.disconnect(promise);
}
public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
this.unsafe.close(promise);
}
public void deregister(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
this.unsafe.deregister(promise);
}
public void read(ChannelHandlerContext ctx) {
this.unsafe.beginRead();
}
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
this.unsafe.write(msg, promise);
}
public void flush(ChannelHandlerContext ctx) throws Exception {
this.unsafe.flush();
}
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.fireExceptionCaught(cause);
}
}
TailContext主要就是对输入数据的一个收尾工作，它的很多方法都为空。
static final class TailContext extends AbstractChannelHandlerContext implements ChannelInboundHandler {
private static final String TAIL_NAME = DefaultChannelPipeline.generateName0(DefaultChannelPipeline.TailContext.class);
TailContext(DefaultChannelPipeline pipeline) {
super(pipeline, (EventExecutorGroup)null, TAIL_NAME, true, false);
}
public ChannelHandler handler() {
return this;
}
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
}
public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
}
public void channelActive(ChannelHandlerContext ctx) throws Exception {
}
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
}
public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
}
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
}
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
}
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
}
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
DefaultChannelPipeline.logger.warn("An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception.", cause);
}
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try {
DefaultChannelPipeline.logger.debug("Discarded inbound message {} that reached at the tail of the pipeline. Please check your pipeline configuration.", msg);
} finally {
ReferenceCountUtil.release(msg);
}
}
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
}
标签：close ase log 默认 oca let card map void
原文地址：https://www.cnblogs.com/xiaobaituyun/p/10803521.html
