我想在flutter中将File转换为ByteData对象。像这样:import'dart:io';Filefile=getSomeCorrectFile();//ThisfileiscorrectByteDatabytes=ByteData(file.readAsBytesSync());//Doesntcompilereturnbytes;我知道ByteData构造函数接收字节数量的长度并用0初始化它们，所以我可以做类似ByteData(file.readAsBytesStync().length);但是我该如何填充它们呢？我错过了什么？ 最佳答案
我想在flutter中将File转换为ByteData对象。像这样:import'dart:io';Filefile=getSomeCorrectFile();//ThisfileiscorrectByteDatabytes=ByteData(file.readAsBytesSync());//Doesntcompilereturnbytes;我知道ByteData构造函数接收字节数量的长度并用0初始化它们，所以我可以做类似ByteData(file.readAsBytesStync().length);但是我该如何填充它们呢？我错过了什么？ 最佳答案
如何在initState中访问Provider的上下文一直报错flutter:ThefollowingassertionwasthrownbuildingBuilder:flutter:inheritFromWidgetOfExactType(_Provider)orinheritFromElement()wascalledbeforeflutter:_ProductDetailsPageState.initState()completed.每当我运行下面的代码时if(Provider.of(context).selectedProduct==null){product=Product
如何在initState中访问Provider的上下文一直报错flutter:ThefollowingassertionwasthrownbuildingBuilder:flutter:inheritFromWidgetOfExactType(_Provider)orinheritFromElement()wascalledbeforeflutter:_ProductDetailsPageState.initState()completed.每当我运行下面的代码时if(Provider.of(context).selectedProduct==null){product=Product
我在androidstudio中运行flutter代码时遇到异常。I/flutter(5360):══╡EXCEPTIONCAUGHTBYWIDGETSLIBRARY╞═══════════════════════════════════════════════════════════I/flutter(5360):ThefollowingassertionwasthrownbuildingText("xyz"):I/flutter(5360):NoDirectionalitywidgetfound.I/flutter(5360):RichTextwidgetsrequireaDire
我在androidstudio中运行flutter代码时遇到异常。I/flutter(5360):══╡EXCEPTIONCAUGHTBYWIDGETSLIBRARY╞═══════════════════════════════════════════════════════════I/flutter(5360):ThefollowingassertionwasthrownbuildingText("xyz"):I/flutter(5360):NoDirectionalitywidgetfound.I/flutter(5360):RichTextwidgetsrequireaDire
我怎样才能使底部FAB像下图一样？这是我当前的代码示例:class_ItemDetailsStateextendsState{@overrideWidgetbuild(BuildContextcontext){doubleheight=MediaQuery.of(context).size.height*0.42;returnScaffold(body:Stack(children:[CustomScrollView(slivers:[...],),Positioned(bottom:0,child:FloatingActionButton(elevation:4,onPressed:
我怎样才能使底部FAB像下图一样？这是我当前的代码示例:class_ItemDetailsStateextendsState{@overrideWidgetbuild(BuildContextcontext){doubleheight=MediaQuery.of(context).size.height*0.42;returnScaffold(body:Stack(children:[CustomScrollView(slivers:[...],),Positioned(bottom:0,child:FloatingActionButton(elevation:4,onPressed:
我想使用截图中的二进制主体上传文件:到目前为止我只有:save()async{http.put(url,headers:headers,body:); 最佳答案 bodyput的参数方法接受List将用作字节列表来自httpAPI引用:https://pub.dev/documentation/http/latest/http/put.htmlbodysetsthebodyoftherequest.ItcanbeaString,aListoraMap.Ifit'saString,it'sencodedusingencodingand
我想使用截图中的二进制主体上传文件:到目前为止我只有:save()async{http.put(url,headers:headers,body:); 最佳答案 bodyput的参数方法接受List将用作字节列表来自httpAPI引用:https://pub.dev/documentation/http/latest/http/put.htmlbodysetsthebodyoftherequest.ItcanbeaString,aListoraMap.Ifit'saString,it'sencodedusingencodingand
