下面是上传音视频流的截图，先保存在缓存，然后请求接口，成功或者失败会删除文件。
可以在Device File Explorer查看，
Android:

会返回 /data/data//cache 这个目录,是应用私有的缓存目录。

iOS:

会返回 Library/Caches 下的一个目录,是应用共享的缓存目录。

  //上传音视频截图postSnapshotRequest({required int sendUserId,required int recUserId,required String order,required Uint8List imageBytes}) async {final tempDir = await getTemporaryDirectory();var file = await File('${tempDir.path}/image_${DateTime.now().millisecondsSinceEpoch}.jpg').create();file.writeAsBytesSync(imageBytes);PrintUtil.prints('图片裁剪 文件地址：${file.path}');String path = file.path;String name = path.substring(path.lastIndexOf('/') + 1, path.length);PrintUtil.prints("tag_图片路径path $path");PrintUtil.prints("tag_图片路径name $name");var attFile = await MultipartFile.fromFile(path, filename: name);FormData formData = FormData.fromMap({'capture_img': attFile,"order_no": order,"c_user_id": sendUserId,"r_user_id": recUserId});httpReq.HttpRequest.intance.postHttpFromBusiness(Api.AUDIO_AND_VIDEO_CAPTURE, (data) {deleteFile(path);}, (error, errorCode) {deleteFile(path);}, parameters: formData);}void deleteFile(String filepath) {var file = File(filepath);if (file.existsSync()) {file.deleteSync();}}