Netty相关ChildHandler

IdleStateHandler
心跳Handler
https://blog.csdn.net/weixin_43935927/article/details/112001309

LengthFieldPrepender
将当前发送消息的二进制字节长度，添加到缓冲区头部
https://blog.csdn.net/cgj296645438/article/details/90667419

LengthFieldBasedFrameDecoder
自定义长度解码器
https://www.jianshu.com/p/64dc7ee8c713