1.生命周期
2.ChannelInboundHandler事件
3.ByteBuf的释放
3.1显式释放
3.2 SimpleChannelInboundHandler自动释放
重写channelRead0方法
public class SimpleDiscardHandler
extends SimpleChannelInboundHandler<Object> {
@Override
public void channelRead0(ChannelHandlerContext ctx,
Object msg) {
// No need to do anything special
}
}
参考:
Netty4(十三):SimpleChannelInBoundHandler 源码分析
4.ChannelOutboundHandler事件
出站操作和数据将由 ChannelOutboundHandler 处理。它的方法将被 Channel、ChannelPipeline 以及 ChannelHandlerContext 调用。
ChannelOutboundHandler 的一个强大的功能是可以按需推迟操作或者事件,这使得可
以通过一些复杂的方法来处理请求。例如, 如果到远程节点的写入被暂停了, 那么你可以推迟冲
刷操作并在稍后继续。
表6-4显示了所有由ChannelOutboundHandler本身所定义的方法(忽略了那些从ChannelHandler 继承的方法)
5.ChannelHandler适配器
6.ChannelDuplexHandler
同时实现了ChannelInboundHandler和ChannelOutboundHandler
public class ChannelDuplexHandler extends ChannelInboundHandlerAdapter implements ChannelOutboundHandler {
}
7.CombinedChannelDuplexHandler
CombinedChannelDuplexHandler继承自ChannelDuplexHandler,其需要传入ChannelInboundHandler和ChannelOutboundHandler,本质上其是一个代理对象
public class CombinedChannelDuplexHandler<I extends ChannelInboundHandler, O extends ChannelOutboundHandler>
extends ChannelDuplexHandler {
private static final InternalLogger logger = InternalLoggerFactory.getInstance(CombinedChannelDuplexHandler.class);
private DelegatingChannelHandlerContext inboundCtx;
private DelegatingChannelHandlerContext outboundCtx;
private volatile boolean handlerAdded;
private I inboundHandler;
private O outboundHandler;
/**
* Creates a new uninitialized instance. A class that extends this handler must invoke
* {@link #init(ChannelInboundHandler, ChannelOutboundHandler)} before adding this handler into a
* {@link ChannelPipeline}.
*/
protected CombinedChannelDuplexHandler() {
ensureNotSharable();
}
/**
* Creates a new instance that combines the specified two handlers into one.
*/
public CombinedChannelDuplexHandler(I inboundHandler, O outboundHandler) {
ensureNotSharable();
init(inboundHandler, outboundHandler);
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
assert ctx == inboundCtx.ctx;
if (!inboundCtx.removed) {
inboundHandler.channelActive(inboundCtx);
} else {
inboundCtx.fireChannelActive();
}
}
@Override
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
assert ctx == outboundCtx.ctx;
if (!outboundCtx.removed) {
outboundHandler.write(outboundCtx, msg, promise);
} else {
outboundCtx.write(msg, promise);
}
}
}