saveToStorage method
将图像保存到存储并返回存储ID
返回 String 存储ID
Implementation
String saveToStorage() {
String uuid = Uuid().v4();
String destFile = FilePath.imagePath + uuid;
if (!File(destFile).existsSync()) {
File(destFile).createSync(recursive: true);
}
this.file.copySync(destFile);
return uuid;
}