Flutter，FileReader()编译到Android时崩溃

Question

我正在开发一个多平台应用程序，它适用于 Android、IOS 和网络。 我为每个平台调用了不同的服务，在其中一个服务中，我使用 FileReader() 从网络版本上传文件，它可以工作，但如果我不评论 FileReader() 对象，它不会让我编译Android版本，输出如下：

Launching lib/main.dart on Mi 9T in debug mode...
Running Gradle task 'assembleDebug'...
Unhandled exception:
Crash when compiling file:///Users/danielcardona/Flutter/ptf_online/ptf_online/lib/pages/datos_page/utils/filepicker_pc.dart,
at character offset 81:
RangeError (offset): Invalid value: Not in range 0..594, inclusive: 7359
#0      RangeError.checkValueInInterval (dart:core/errors.dart:283:7)
#1      Source.getLocation (package:kernel/ast.dart:7277:16)
#2      getLocation (package:front_end/src/fasta/messages.dart:16:52)
#3      ProcessedOptions.format (package:front_end/src/base/processed_options.dart:205:47)
#4      ProcessedOptions.report (package:front_end/src/base/processed_options.dart:228:29)
#5      CompilerContext.report (package:front_end/src/fasta/compiler_context.dart:69:13)
#6      Loader.addMessage (package:front_end/src/fasta/loader.dart:325:20)
#7      Loader.addProblem (package:front_end/src/fasta/loader.dart:287:12)
#8      LibraryBuilderImpl.addProblem (package:front_end/src/fasta/builder/library_builder.dart:284:19)
#9      SourceLibraryBuilder.addProblem (package:front_end/src/fasta/source/source_library_builder.dart:1250:47)
#10     BodyBuilder.addProblem (package:front_end/src/fasta/kernel/body_builder.dart:5611:20)
#11     BodyBuilder.addProblemErrorIfConst (package:front_end/src/fasta/kernel/body_builder.dart:5625:5)
#12     BodyBuilder.buildAbstractClassInstantiationError (package:front_end/src/fasta/kernel/body_builder.dart:5292:5)
#13     BodyBuilder.resolveRedirectingFactoryTargets (package:front_end/src/fasta/kernel/body_builder.dart:1125:13)
#14     BodyBuilder.finishFunction (package:front_end/src/fasta/kernel/body_builder.dart:983:5)
#15     DietListener.listenerFinishFunction (package:front_end/src/fasta/source/diet_listener.dart:908:14)
#16     DietListener.buildFunctionBody (package:front_end/src/fasta/source/diet_listener.dart:941:7)
#17     DietListener.endTopLevelMethod (package:front_end/src/fasta/source/diet_listener.dart:352:5)
#18     Parser.parseTopLevelMethod (package:_fe_analyzer_shared/src/parser/parser_impl.dart:2518:14)
#19     Parser.parseTopLevelMemberImpl (package:_fe_analyzer_shared/src/parser/parser_impl.dart:2372:14)
#20     Parser.parseTopLevelDeclarationImpl (package:_fe_analyzer_shared/src/parser/parser_impl.dart:495:14)
#21     Parser.parseUnit (package:_fe_analyzer_shared/src/parser/parser_impl.dart:352:15)
#22     SourceLoader.buildBody (package:front_end/src/fasta/source/source_loader.dart:329:14)
<asynchronous suspension>
#23     Loader.buildBodies (package:front_end/src/fasta/loader.dart:243:15)
<asynchronous suspension>
#24     KernelTarget.buildComponent.<anonymous closure> (package:front_end/src/fasta/kernel/kernel_target.dart:307:20)
#25     withCrashReporting (package:front_end/src/fasta/crash.dart:122:24)
#26     KernelTarget.buildComponent (package:front_end/src/fasta/kernel/kernel_target.dart:305:12)
#27     generateKernelInternal.<anonymous closure> (package:front_end/src/kernel_generator_impl.dart:149:38)
<asynchronous suspension>
#28     withCrashReporting (package:front_end/src/fasta/crash.dart:122:24)
#29     generateKernelInternal (package:front_end/src/kernel_generator_impl.dart:70:10)
#30     kernelForProgramInternal.<anonymous closure> (package:front_end/src/api_prototype/kernel_generator.dart:61:35)
#31     CompilerContext.runWithOptions.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:135:20)
<asynchronous suspension>
#32     CompilerContext.runInContext.<anonymous closure>.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:123:46)
#33     new Future.sync (dart:async/future.dart:224:31)
#34     CompilerContext.runInContext.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:123:19)
#35     _rootRun (dart:async/zone.dart:1126:13)
#36     _CustomZone.run (dart:async/zone.dart:1023:19)
#37     _runZoned (dart:async/zone.dart:1518:10)
#38     runZoned (dart:async/zone.dart:1465:12)
#39     CompilerContext.runInContext (package:front_end/src/fasta/compiler_context.dart:122:12)
#40     CompilerContext.runWithOptions (package:front_end/src/fasta/compiler_context.dart:133:10)
#41     kernelForProgramInternal (package:front_end/src/api_prototype/kernel_generator.dart:60:32)
#42     kernelForProgram (package:front_end/src/api_prototype/kernel_generator.dart:52:17)
#43     compileToKernel (package:vm/kernel_front_end.dart:320:41)
#44     FrontendCompiler.compile.<anonymous closure> (package:frontend_server/frontend_server.dart:446:54)
#45     new Future.<anonymous closure> (dart:async/future.dart:176:37)
#46     _rootRun (dart:async/zone.dart:1122:38)
#47     _CustomZone.run (dart:async/zone.dart:1023:19)
#48     _CustomZone.runGuarded (dart:async/zone.dart:925:7)
#49     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:965:23)
#50     _rootRun (dart:async/zone.dart:1126:13)
#51     _CustomZone.run (dart:async/zone.dart:1023:19)
#52     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:949:23)
#53     Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:23:15)
#54     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:384:19)
#55     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:418:5)
#56     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:174:12)


#0      DietListener.buildFunctionBody (package:front_end/src/fasta/source/diet_listener.dart:946:7)
#1      DietListener.endTopLevelMethod (package:front_end/src/fasta/source/diet_listener.dart:352:5)
#2      Parser.parseTopLevelMethod (package:_fe_analyzer_shared/src/parser/parser_impl.dart:2518:14)
#3      Parser.parseTopLevelMemberImpl (package:_fe_analyzer_shared/src/parser/parser_impl.dart:2372:14)
#4      Parser.parseTopLevelDeclarationImpl (package:_fe_analyzer_shared/src/parser/parser_impl.dart:495:14)
#5      Parser.parseUnit (package:_fe_analyzer_shared/src/parser/parser_impl.dart:352:15)
#6      SourceLoader.buildBody (package:front_end/src/fasta/source/source_loader.dart:329:14)
<asynchronous suspension>
#7      Loader.buildBodies (package:front_end/src/fasta/loader.dart:243:15)
<asynchronous suspension>
#8      KernelTarget.buildComponent.<anonymous closure> (package:front_end/src/fasta/kernel/kernel_target.dart:307:20)
#9      withCrashReporting (package:front_end/src/fasta/crash.dart:122:24)
#10     KernelTarget.buildComponent (package:front_end/src/fasta/kernel/kernel_target.dart:305:12)
#11     generateKernelInternal.<anonymous closure> (package:front_end/src/kernel_generator_impl.dart:149:38)
<asynchronous suspension>
#12     withCrashReporting (package:front_end/src/fasta/crash.dart:122:24)
#13     generateKernelInternal (package:front_end/src/kernel_generator_impl.dart:70:10)
#14     kernelForProgramInternal.<anonymous closure> (package:front_end/src/api_prototype/kernel_generator.dart:61:35)
#15     CompilerContext.runWithOptions.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:135:20)
<asynchronous suspension>
#16     CompilerContext.runInContext.<anonymous closure>.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:123:46)
#17     new Future.sync (dart:async/future.dart:224:31)
#18     CompilerContext.runInContext.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:123:19)
#19     _rootRun (dart:async/zone.dart:1126:13)
#20     _CustomZone.run (dart:async/zone.dart:1023:19)
#21     _runZoned (dart:async/zone.dart:1518:10)
#22     runZoned (dart:async/zone.dart:1465:12)
#23     CompilerContext.runInContext (package:front_end/src/fasta/compiler_context.dart:122:12)
#24     CompilerContext.runWithOptions (package:front_end/src/fasta/compiler_context.dart:133:10)
#25     kernelForProgramInternal (package:front_end/src/api_prototype/kernel_generator.dart:60:32)
#26     kernelForProgram (package:front_end/src/api_prototype/kernel_generator.dart:52:17)
#27     compileToKernel (package:vm/kernel_front_end.dart:320:41)
#28     FrontendCompiler.compile.<anonymous closure> (package:frontend_server/frontend_server.dart:446:54)
#29     new Future.<anonymous closure> (dart:async/future.dart:176:37)
#30     _rootRun (dart:async/zone.dart:1122:38)
#31     _CustomZone.run (dart:async/zone.dart:1023:19)
#32     _CustomZone.runGuarded (dart:async/zone.dart:925:7)
#33     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:965:23)
#34     _rootRun (dart:async/zone.dart:1126:13)
#35     _CustomZone.run (dart:async/zone.dart:1023:19)
#36     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:949:23)
#37     Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:23:15)
#38     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:384:19)
#39     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:418:5)
#40     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:174:12)

Target kernel_snapshot failed: Exception: Errors during snapshot creation: null
build failed.

FAILURE: Build failed with an exception.

* Where:
Script '/Users/danielcardona/developer/flutter/packages/flutter_tools/gradle/flutter.gradle' line: 792

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command '/Users/danielcardona/developer/flutter/bin/flutter'' finished with non-zero exit value 1

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 10s
Finished with error: Gradle task assembleDebug failed with exit code 1

我用来为网络挑选图片的代码：

import 'package:universal_html/prefer_sdk/html.dart' as html;

startFilePickerPc() {
  html.InputElement uploadInput = html.FileUploadInputElement();
  uploadInput.click();

  uploadInput.onChange.listen((e) {
    // read file content as dataURL
    final files = uploadInput.files;
    if (files.length == 1) {
      final file = files[0];

      final reader = new html.FileReader();
      reader.onLoadEnd.listen((e) {
        print(reader.result);
        //  _handleResult(reader.result);
      });

      reader.readAsDataUrl(file);
    }
  });
}

FileReader() 的任何替代方法，或使其工作的任何方法，无需评论网络服务，为移动设备编译？

非常感谢您的帮助。

Answer 1

Smyk 的回答确实启发了我 ;-)。

因为我不想要这里显示的所有样板代码this SO answer 我使用了这里解释的实现Dart 2 conditional imports，最后我是这样使用的：

import "package:ptf_online/utils/filepicker_pc.dart" if (dart.library.io) "package:ptf_online/utils/filepicker_device.dart";

每个平台都有我的类 startFilePicker()。

Answer 2

您可以将特定于平台的代码包装在一个通用接口中，但将特定于平台的实现拉出以分离 .dart 文件。然后您可以使用条件import 将相关实现包含到您的构建中。

请参阅this SO answer 获取灵感。