文件没有正确转换为base64字符串

Question

因此，我编写了一些代码来使用better_camera包从用户捕获图像，然后将其存储在文件中。然后我将其转换为base64字符串以供进一步使用。似乎图像得到妥善保存，因为图像。文件显示了图像。但是当我将图像转换为base64string时，它给出了一个小白色屏幕的图像。我不知道问题出在哪里。谁来检查一下?

import 'dart:convert';
import 'dart:io';
import 'dart:math';
import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:flutter_better_camera/camera.dart';
import 'package:frappe/flutter_flow/flutter_flow_theme.dart';
import 'package:path_provider/path_provider.dart';
class AddNewCameraItem extends StatefulWidget {
const AddNewCameraItem({Key key}) : super(key: key);
@override
_AddNewCameraItemState createState() => _AddNewCameraItemState();
}
class _AddNewCameraItemState extends State<AddNewCameraItem> {
CameraController controller;
@override
void initState() {
super.initState();
initCam();
}
void initCam() async {
List<CameraDescription> cameras = await availableCameras();
controller = CameraController(cameras[0], ResolutionPreset.max);
controller.initialize().then((_) {
controller.setFlashMode(FlashMode.off);
if (!mounted) {
return;
}
setState(() {});
});
}
@override
void dispose() {
controller?.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: FlutterFlowTheme.secondaryColor,
automaticallyImplyLeading: true,
centerTitle: true,
title: Text(
'ADD NEW ITEMS',
style: FlutterFlowTheme.bodyText1.override(
fontFamily: 'Noto Serif',
color: Color(0xFFFAFAFA),
fontSize: 20,
fontWeight: FontWeight.w600,
),
),
elevation: 4,
),
body: !controller.value.isInitialized
? Container()
// : Image.file(File(
//     '/data/user/0/com.flutterflow.frappe/cache/lkpbpyigaqpjsh6iygy8dA4dsFDG9CAcVD7DueDLtd3C3JqzmmRuZcKaFFmAt88Ryyp208CzlE1oYfkJKnvwErBFv3DkO0dSYLZApETWDnsGOur728R7WgoUQ1EEOv9ilz1jAeNLotSsYFaI13Jk9wp5mmGdqhmRx6LYSCfHQHAdalrMCtniqrU3Sqhaw1iJZfeuUsJy.jpg')),
: MaterialApp(
home: CameraPreview(controller),
),
floatingActionButton: FloatingActionButton(
onPressed: () async {
try {
Directory tempDir = await getTemporaryDirectory();
String randomName =
tempDir.path + '/' + getRandomString(200) + '.jpg';
// await controller.takePicture(randomName);
File file = File(
'/data/user/0/com.flutterflow.frappe/cache/IfXsEjNsSifPiQJ0d628j2d1HRh2Ww2Flin3urZc4d59WYeZ9DQ8mjpLdrt2jwzBjn2vxqvnkzRd4AGowI6fKCGRNWOfei7B2KufbpOG0RsNH7mobwGa7KS7q1C6ALoNIVJ13XLqpa7BX7pIQSgLobe5lW6z7P01QBms3CVrM9omeEvIZxRwxL5s555HLOGN4Te9Bta2.jpg');
Uint8List list = await file.readAsBytes();
print(list);
print(base64Encode(list.toList()));
print("Random n: " + randomName);
// print(base64Encode((await xfile.readAsBytes()).toList()));
} catch (e) {
print("Error: " + e.toString());
}
},
child: Center(
child: Icon(Icons.camera_alt, color: FlutterFlowTheme.tertiaryColor),
),
),
);
}
String getRandomString(int length) {
String _chars =
'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890';
Random _rnd = Random();
return String.fromCharCodes(Iterable.generate(
length, (_) => _chars.codeUnitAt(_rnd.nextInt(_chars.length))));
}
}

BASE64OUTPUT

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

UINT8LIST

[255, 216, 255, 225, 11, 171, 69, 120, 105, 102, 0, 0, 77, 77, 0, 42, 0, 0, 0, 8, 0, 11, 1, 15, 0, 2, 0, 0, 0, 7, 0, 0, 0, 146, 1, 16, 0, 2, 0, 0, 0, 17, 0, 0, 0, 154, 1, 18, 0, 3, 0, 0, 0, 1, 0, 6, 0, 0, 1, 26, 0, 5, 0, 0, 0, 1, 0, 0, 0, 172, 1, 27, 0, 5, 0, 0, 0, 1, 0, 0, 0, 180, 1, 40, 0, 3, 0, 0, 0, 1, 0, 2, 0, 0, 1, 49, 0, 2, 0, 0, 0, 61, 0, 0, 0, 188, 1, 50, 0, 2, 0, 0, 0, 20, 0, 0, 0, 250, 2, 19, 0, 3, 0, 0, 0, 1, 0, 1, 0, 0, 135, 105, 0, 4, 0, 0, 0, 1, 0, 0, 1, 14, 136, 37, 0, 4, 0, 0, 0, 1, 0, 0, 2, 242, 0, 0, 2, 248, 88, 105, 97, 111, 109, 105, 0, 0, 82, 101, 100, 109, 105, 32, 78, 111, 116, 101, 32, 53, 32, 80, 114, 111, 0, 0, 0, 0, 0, 72, 0, 0, 0, 1, 0, 0, 0, 72, 0, 0, 0, 1, 119, 104, 121, 114, 101, 100, 45, 117, 115, 101, 114, 32, 57, 32, 80, 75, 81, 49, 46, 49, 56, 48, 57, 48, 52, 46, 48, 48, 49, 32, 86, 49, 49, 46, 48, 46, 53, 46, 48, 46, 80, 69, 73, 77, 73, 88, 77, 32, 114, 101, 108, 101, 97, 115, 101, 45, 107, 101, 121, 115, 0, 0, 50, 48, 50, 49, 58, 48, 56, 58, 49, 56, 32, 49, 57, 58, 49, 5

Answer 1

在使用Base64字符串之前必须解码

String encoded = stringToBase64.encode(credentials); 
String decoded = stringToBase64.decode(encoded);