DataChannel 继承自： ABC

Abstract widget-facing byte channel.

方法

名称	类型	默认值	说明
on_bytes	None	—	Register a handler for bytes pushed from Dart. Pass None to clear. The handler runs synchronously on whatever thread the transport delivers from — push heavy work to a queue/worker.
send	None	—	Send bytes Python → Dart. Fire-and-forget.
close	None	—	Release the channel. Idempotent.