无法打开文件，路径 = 'file:///path'（操作系统错误：没有那个文件或目录，错误号 = 2）

Question

嗨，我正在尝试使用图像库减小从图库中选取的图像大小，同时尝试遇到这样的错误

E/flutter (13796): [ERROR:lib/tonic/logging/dart_error.cc(16)]    Unhandled exception:
E/flutter (13796): FileSystemException: Cannot open file, path = 'file:///storage/emulated/0/WhatsApp/Media/WhatsApp%20Images/IMG-20171016-WA0020.jpg' (OS Error: No such file or directory, errno = 2)
E/flutter (13796): #0      _File.throwIfError (file_impl.dart:618)
E/flutter (13796): #1      _File.openSync (file_impl.dart:473)
E/flutter (13796): #2      _File.readAsBytesSync (file_impl.dart:533)
E/flutter (13796): #3      _AddNewUserState.qqq (/data/data/com.prayuta.chitfunds/cache/chitfundsUNFPRG/chitfunds/lib/users.dart:420:97)
E/flutter (13796): <asynchronous suspension>
E/flutter (13796): #4      _AddNewUserState.build.<anonymous closure> (/data/data/com.prayuta.chitfunds/cache/chitfundsUNFPRG/chitfunds/lib/users.dart:686:19)
E/flutter (13796): #5      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter (13796): #6      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:149:9)
E/flutter (13796): #7      TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:119:7)
E/flutter (13796): #8      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
E/flutter (13796): #9          BindingBase&SchedulerBinding&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:147:20)
E/flutter (13796): #10     BindingBase&SchedulerBinding&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
E/flutter (13796): #11     BindingBase&SchedulerBinding&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
E/flutter (13796): #12     BindingBase&SchedulerBinding&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
E/flutter (13796): #13     BindingBase&SchedulerBinding&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
E/flutter (13796): #14     _invoke1 (file:///b/build/slave/Linux_Engine/build/src/flutter/lib/ui/hooks.dart:100)
   E/flutter (13796): #15     _dispatchPointerDataPacket (file:///b/build/slave/Linux_Engine/build/src/flutter/lib/ui/hooks.dart:58)

任何人都可以帮助我的代码看起来像这样

import 'package:image/image.dart' as convertinglib;
File imageFile = await ImagePicker.pickImage();
convertinglib.Image image = convertinglib.decodeImage(new Io.File(imageFile.uri.toString()).readAsBytesSync());
convertinglib.Image thumbnail = convertinglib.copyResize(image, 120);

Answer 1

问题不在于使用图像选择器读取文件或转换为较小的大小，而在于将文件写入文件系统。我认为，您采用了dart 映像包的示例代码 ，该代码在调整文件大小后将文件写入文件系统。这种形式在智能手机上是不可能的。

您发布的代码实际上并未导致错误，但这一行却导致了错误：

new Io.File(imageFile.uri.toString())
   ..writeAsBytesSync(convertingLib.encodePng(thumbnail))

这样做的问题是 imagePicker 隐藏了图像的真实 uri。它给你一个看起来像这样的路径：.../tmp/image_picker_1547A964-791E-426F-A682-33D3AFA995BA-18295-0003861F9255294A.jpg它不能用来保存你的新缩略图。

您可以尝试避免首先保存文件，或者将其保存到实际存在的位置（例如，您可以使用path_provider 插件来实现此目的）。