server.go
func (ctx *RequestCtx) SetBodyStream(bodyStream io.Reader, bodySize int) {
	ctx.Response.SetBodyStream(bodyStream, bodySize)
}
func (ctx *RequestCtx) SetBodyStream(bodyStream io.Reader, bodySize int) {
	ctx.Response.SetBodyStream(bodyStream, bodySize)
}
// SetBodyStream sets response body stream and, optionally body size.
//
// bodyStream.Close() is called after finishing reading all body data
// if it implements io.Closer.
//
// If bodySize is >= 0, then bodySize bytes must be provided by bodyStream
// before returning io.EOF.
//
// If bodySize < 0, then bodyStream is read until io.EOF.
//
// See also SetBodyStreamWriter.