将图像编码为 base64 字符串

Question

我尝试使用库image_picker从dart中的照片库上传图像..工作正常..

然后我尝试将所选图像转换为 Bas64 字符串，如下所示：

imageSelectorGallery() async {
_image = await ImagePicker.pickImage(
source: ImageSource.gallery,
// maxHeight: 50.0,
// maxWidth: 50.0,
);
List<int> imageBytes = _image.readAsBytesSync();
print(imageBytes);
String base64Image = base64Encode(imageBytes);
print('string is');
print(base64Image);
print("You selected gallery image : " + _image.path);
setState(() {});
}

但这不断返回一个不正确的字符串..例如：

_9j_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_-AAEEpGSUYAAQEAAAEAAQAA_9sAQwACAQEBAQECAQEBAgICAgIEAwICAgIFBAQDBAYFBgYGBQYGBgcJCAYHCQcGBggLCAkKCgoKCgYICwwLCgwJCgoK_9sAQwECAgICAgIFAwMFCgcGBwoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoKCgoK_8AAEQgFAAPAAwEiAAIRAQMRAf_EAB8AAAEFAQEBAQEBAAAAAAAAAAABAgMEBQYHCAkKC__EALUQAAIBAwMCBAMFBQQEAAABfQECAwAEEQUSITFBBhNRYQcicRQygZGhCCNCscEVUtHwJDNicoIJChYXGBkaJSYnKCkqNDU2Nzg5OkNERUZHSElKU1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6g4SFhoeIiYq

并且这无法转换为图像..

问题在哪里以及如何解决？

Answer 1

您只将编码字符串的前 1024 个字符复制到问题中。也许print命令截断了它。此外，在线工具似乎更喜欢(需要？(URL安全版本，因此正如Günter所说，使用base64UrlEncode。

要确认您使用的字符串的长度大致正确，请添加 33%。也就是说，2k 图像将转换为大约 2667 个字符长的字符串。