如何在颤动中将图像文件转换为base64字符串？答案

【问题标题】：How to convert image file to base64 String in flutter?如何在颤动中将图像文件转换为base64字符串？
【发布时间】：2020-10-29 09:54:30
【问题描述】：

我正在尝试在颤振中转换图像文件：

 File _img=new File('/data/user/0/com.example.test3/app_flutter/2020-10-29T17:18:56.210347.png');
 List<int> imageBytes = _img.readAsBytesSync();
 String imageB64 = base64Encode(imageBytes);
 print(imageB64);

但它看起来像是一个错误的 base64 字符串，我无法在转换网站上解码为图像： https://codebeautify.org/base64-to-image-converter

iVBORw0KGgoAAAANSUhEUgAAAhwAAALECAYAAABDk+k+AAAAAXNSR0IArs4c6QAAAARzQklUCAgICHwIZIgAACAASURBVHic7d1ngFx1ucDhd9N77z0hbdMhCSAJVZoURS4C0psColcxFBXFKypKUywUQYp0EdtVQHpHTQLpZZOQnpDee9v7QeUSksxsyP7Ptuf5tnPeybwfCPvLmTNnIgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAgNJRUFYvXFxcXFxWrw0AVVVBQUGZ/O6vVhYvCgBULYIDAEhOcAAAyQkOACA5wQEAJCc4AIDkBAcAkJzgAACSExwAQHKCAwBITnAAAMkJDgAgOcEBACQnOACA5AQHAJCc4AAAkhMcAEByggMASE5wAADJCQ4AIDnBAQAkJzgAgOQEBwCQnOAAAJITHABAcoIDAEhOcAAAyQkOACA5wQEAJCc4AIDkBAcAkJzgAACSExwAQHKCAwBITnAAAMkJDgAgOcEBACQnOACA5AQHAJCc4AAAkhMcAEByggMASE5wAADJCQ4AIDnBAQAkJzgAgOQEBwCQnOAAAJITHABAcoIDAEhOcAAAyQkOACA5wQEAJCc4AIDkBAcAkJzgAACSExwAQHKCAwBITnAAAMkJDgAgOcEBACQnOACA5AQHAJCc4AAAkhMcAEByggMASE5wAADJCQ4AIDnBAQAkJzgAgOQEBwCQnOAAAJITHABAcoIDAEhOcAAAyQkOACA5wQEAJCc4AIDkBAcAkJzgAACSExwAQHKCAwBITnAAAMkJDgAgOcEBACQnOACA5AQHAJCc4AAAkhMcAEByggMASE5wAADJCQ4AIDnBAQAkJzgAgOQEBwCQnOAAAJITHABAcoIDAEhOcAAAyQkOACA5wQEAJCc4AIDkBAcAkJzgAACSExwAQHKCAwBITnAAAMkJDgAgOcEBACQnOACA5AQHAJCc4AAAkhM

dart base64 格式是否与其他格式不同？谢谢。

【问题讨论】：

标签： file flutter dart base64

【解决方案1】：

您必须将字节转换为 Uint8List 对象而不是 List<int>：

File _img = File(
   '/data/user/0/com.example.test3/app_flutter/2020-10-29T17:18:56.210347.png');
final bytes = Uint8List.fromList(_img.readAsBytesSync());
final imgBase64 = base64Encode(bytes);
print(imgBase64);

【讨论】：

【解决方案2】：

我发现这种情况下，'print' 函数无法完全显示 base64 代码。如果要验证，需要导出到文本文件：

 _write(String text) async {
    final File file = File('/storage/emulated/0/xxx/my_file.txt');
    await file.writeAsString(text);
    print(file);
  }

【讨论】：