- html - 出于某种原因,IE8 对我的 Sass 文件中继承的 html5 CSS 不友好?
- JMeter 在响应断言中使用 span 标签的问题
- html - 在 :hover and :active? 上具有不同效果的 CSS 动画
- html - 相对于居中的 html 内容固定的 CSS 重复背景?
Flutte / Dart的新手。是什么导致我的映射问题?
import 'dart:async';
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
Future<List<Photo>> fetchPhotos(http.Client client) async {
final response =
await client.get('https://cloud.iexapis.com/stable/stock/market/batch?symbols=aapl,fb&types=quote&token=hidden');
// Use the compute function to run parsePhotos in a separate isolate.
return compute(parsePhotos, response.body);
}
// A function that converts a response body into a List<Photo>.
List<Photo> parsePhotos(String response) {
List<Photo> Photos = new List<Photo>();
List parsePhotos= json.decode(response.toString());
for (int i = 0; i < parsePhotos.length; i++) {
Photos.add(new Photo.fromJson(parsePhotos[i]));
}
return Photos;
}
class Photo {
final String symbol;
final String companyName;
final String primaryExchange;
final String calculationPrice;
final int open;
final int openTime;
final double close;
final int closeTime;
final double high;
final double low;
final double latestPrice;
final String latestSource;
final String latestTime;
final int latestUpdate;
final int latestVolume;
final dynamic iexRealtimePrice;
final dynamic iexRealtimeSize;
final dynamic iexLastUpdated;
final double delayedPrice;
final int delayedPriceTime;
final double extendedPrice;
final double extendedChange;
final double extendedChangePercent;
final int extendedPriceTime;
final double previousClose;
final int previousVolume;
final int change;
final double changePercent;
final int volume;
final dynamic iexMarketPercent;
final dynamic iexVolume;
final int avgTotalVolume;
final dynamic iexBidPrice;
final dynamic iexBidSize;
final dynamic iexAskPrice;
final dynamic iexAskSize;
final int marketCap;
final double peRatio;
final double week52High;
final int week52Low;
final double ytdChange;
final int lastTradeTime;
final bool isUsMarketOpen;
Photo({
this.symbol,
this.companyName,
this.primaryExchange,
this.calculationPrice,
this.open,
this.openTime,
this.close,
this.closeTime,
this.high,
this.low,
this.latestPrice,
this.latestSource,
this.latestTime,
this.latestUpdate,
this.latestVolume,
this.iexRealtimePrice,
this.iexRealtimeSize,
this.iexLastUpdated,
this.delayedPrice,
this.delayedPriceTime,
this.extendedPrice,
this.extendedChange,
this.extendedChangePercent,
this.extendedPriceTime,
this.previousClose,
this.previousVolume,
this.change,
this.changePercent,
this.volume,
this.iexMarketPercent,
this.iexVolume,
this.avgTotalVolume,
this.iexBidPrice,
this.iexBidSize,
this.iexAskPrice,
this.iexAskSize,
this.marketCap,
this.peRatio,
this.week52High,
this.week52Low,
this.ytdChange,
this.lastTradeTime,
this.isUsMarketOpen,
});
factory Photo.fromJson(String str) => Photo.fromMap(json.decode(str));
String toJson() => json.encode(toMap());
factory Photo.fromMap(Map<String, dynamic> json) => Photo(
symbol: json["symbol"],
companyName: json["companyName"],
primaryExchange: json["primaryExchange"],
calculationPrice: json["calculationPrice"],
open: json["open"],
openTime: json["openTime"],
close: json["close"].toDouble(),
closeTime: json["closeTime"],
high: json["high"].toDouble(),
low: json["low"].toDouble(),
latestPrice: json["latestPrice"].toDouble(),
latestSource: json["latestSource"],
latestTime: json["latestTime"],
latestUpdate: json["latestUpdate"],
latestVolume: json["latestVolume"],
iexRealtimePrice: json["iexRealtimePrice"],
iexRealtimeSize: json["iexRealtimeSize"],
iexLastUpdated: json["iexLastUpdated"],
delayedPrice: json["delayedPrice"].toDouble(),
delayedPriceTime: json["delayedPriceTime"],
extendedPrice: json["extendedPrice"].toDouble(),
extendedChange: json["extendedChange"].toDouble(),
extendedChangePercent: json["extendedChangePercent"].toDouble(),
extendedPriceTime: json["extendedPriceTime"],
previousClose: json["previousClose"].toDouble(),
previousVolume: json["previousVolume"],
change: json["change"],
changePercent: json["changePercent"].toDouble(),
volume: json["volume"],
iexMarketPercent: json["iexMarketPercent"],
iexVolume: json["iexVolume"],
avgTotalVolume: json["avgTotalVolume"],
iexBidPrice: json["iexBidPrice"],
iexBidSize: json["iexBidSize"],
iexAskPrice: json["iexAskPrice"],
iexAskSize: json["iexAskSize"],
marketCap: json["marketCap"],
peRatio: json["peRatio"].toDouble(),
week52High: json["week52High"].toDouble(),
week52Low: json["week52Low"],
ytdChange: json["ytdChange"].toDouble(),
lastTradeTime: json["lastTradeTime"],
isUsMarketOpen: json["isUSMarketOpen"],
);
Map<String, dynamic> toMap() => {
"symbol": symbol,
"companyName": companyName,
"primaryExchange": primaryExchange,
"calculationPrice": calculationPrice,
"open": open,
"openTime": openTime,
"close": close,
"closeTime": closeTime,
"high": high,
"low": low,
"latestPrice": latestPrice,
"latestSource": latestSource,
"latestTime": latestTime,
"latestUpdate": latestUpdate,
"latestVolume": latestVolume,
"iexRealtimePrice": iexRealtimePrice,
"iexRealtimeSize": iexRealtimeSize,
"iexLastUpdated": iexLastUpdated,
"delayedPrice": delayedPrice,
"delayedPriceTime": delayedPriceTime,
"extendedPrice": extendedPrice,
"extendedChange": extendedChange,
"extendedChangePercent": extendedChangePercent,
"extendedPriceTime": extendedPriceTime,
"previousClose": previousClose,
"previousVolume": previousVolume,
"change": change,
"changePercent": changePercent,
"volume": volume,
"iexMarketPercent": iexMarketPercent,
"iexVolume": iexVolume,
"avgTotalVolume": avgTotalVolume,
"iexBidPrice": iexBidPrice,
"iexBidSize": iexBidSize,
"iexAskPrice": iexAskPrice,
"iexAskSize": iexAskSize,
"marketCap": marketCap,
"peRatio": peRatio,
"week52High": week52High,
"week52Low": week52Low,
"ytdChange": ytdChange,
"lastTradeTime": lastTradeTime,
"isUSMarketOpen": isUsMarketOpen,
};
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
final appTitle = 'Isolate Demo';
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title),
),
body: FutureBuilder<List<Photo>>(
future: fetchPhotos(http.Client()),
builder: (context, snapshot) {
if (snapshot.hasError) print(snapshot.error);
return snapshot.hasData
? PhotosList(photos: snapshot.data)
: Center(child: CircularProgressIndicator());
},
),
);
}
}
class PhotosList extends StatelessWidget {
final List<Photo> photos;
// final parsePhotos = json.decode(response.body).cast<Map<String, dynamic>>();
PhotosList({Key key, this.photos}) : super(key: key);
@override
Widget build(BuildContext context) {
return GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
),
itemCount: photos.length,
itemBuilder: (context, index) {
return Image.network(photos[index].companyName);
},
);
}
}
Launching lib\main.dart on Android SDK built for x86 in debug mode...
Initializing gradle...
Resolving dependencies...
Running Gradle task 'assembleDebug'...
Built build\app\outputs\apk\debug\app-debug.apk.
Flutter is taking longer than expected to report its views. Still trying...
I/OpenGLRenderer( 5371): Initialized EGL, version 1.4
D/OpenGLRenderer( 5371): Swap behavior 1
D/ ( 5371): HostConnection::get() New Host Connection established 0xdd5d9200, tid 5399
D/EGL_emulation( 5371): eglCreateContext: 0xde80f4c0: maj 2 min 0 rcv 2
D/EGL_emulation( 5371): eglMakeCurrent: 0xde80f4c0: ver 2 0 (tinfo 0xde37faf0)
D/ ( 5371): HostConnection::get() New Host Connection established 0xc8bb7680, tid 5390
D/EGL_emulation( 5371): eglCreateContext: 0xde37cc00: maj 2 min 0 rcv 2
D/EGL_emulation( 5371): eglMakeCurrent: 0xde37cc00: ver 2 0 (tinfo 0xde37f810)
I/Choreographer( 5371): Skipped 411 frames! The application may be doing too much work on its main thread.
D/EGL_emulation( 5371): eglMakeCurrent: 0xde80f4c0: ver 2 0 (tinfo 0xde37faf0)
Syncing files to device Android SDK built for x86...
I/OpenGLRenderer( 5371): Davey! duration=8078ms; Flags=1, IntendedVsync=1110681936778, Vsync=1117531936504, OldestInputEvent=9223372036854775807, NewestInputEvent=0, HandleInputStart=1117546732479, AnimationStart=1117546825482, PerformTraversalsStart=1117546831170, DrawStart=1117600733845, SyncQueued=1117602574377, SyncStart=1117645210311, IssueDrawCommandsStart=1117645436189, SwapBuffers=1118338480166, FrameCompleted=1118803458523, DequeueBufferDuration=29600000, QueueBufferDuration=176000,
D/EGL_emulation( 5371): eglMakeCurrent: 0xde37cc00: ver 2 0 (tinfo 0xde37f810)
I/flutter ( 5371): Exception: type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List<dynamic>'
{"AAPL":{"stats":{"week52change":0.232986,"week52high":255.93,"week52low":142,"marketcap":1136677331400,"employees":137000,"day200MovingAvg":199.29,"day50MovingAvg":225.28,"float":4436680630.59,"avg10Volume":26482506.4,"avg30Volume":26817874.5,"ttmEPS":11.9342,"ttmDividendRate":3,"companyName":"Apple, Inc.","sharesOutstanding":4443270000,"maxChangePercent":252.2871,"year5ChangePercent":1.3384,"year2ChangePercent":0.5329,"year1ChangePercent":0.1512,"ytdChangePercent":0.6199,"month6ChangePercent":0.2152,"month3ChangePercent":0.2274,"month1ChangePercent":0.1391,"day30ChangePercent":0.1696,"day5ChangePercent":0.0272,"nextDividendDate":"2019-11-07","dividendYield":0.011726995543741695,"nextEarningsDate":"2020-02-04","exDividendDate":"2019-11-07","peRatio":21.44,"beta":1.534927573962706},"quote":{"symbol":"AAPL","companyName":"Apple, Inc.","primaryExchange":"NASDAQ","calculationPrice":"close","open":249.5,"openTime":1572615000544,"close":255.82,"closeTime":1572638400572,"high":255.93,"low":249.16,"latestPrice":255.82,"latestSource":"Close","latestTime":"November 1, 2019","latestUpdate":1572638400572,"latestVolume":38139225,"iexRealtimePrice":null,
{"AAPL":{"stats":{"week52change":0.232986,"week52high":255.93,"week52low":142,"marketcap":1136677331400,"employees":137000,"day200MovingAvg":199.29,"day50MovingAvg":225.28,"float":4436680630.59,"avg10Volume":26482506.4,"avg30Volume":26817874.5,"ttmEPS":11.9342,"ttmDividendRate":3,"companyName":"Apple, Inc.","sharesOutstanding":4443270000,"maxChangePercent":252.2871,"year5ChangePercent":1.3384,"year2ChangePercent":0.5329,"year1ChangePercent":0.1512,"ytdChangePercent":0.6199,"month6ChangePercent":0.2152,"month3ChangePercent":0.2274,"month1ChangePercent":0.1391,"day30ChangePercent":0.1696,"day5ChangePercent":0.0272,"nextDividendDate":"2019-11-07","dividendYield":0.011726995543741695,"nextEarningsDate":"2020-02-04","exDividendDate":"2019-11-07","peRatio":21.44,"beta":1.534927573962706},"quote":{"symbol":"AAPL","companyName":"Apple, Inc.","primaryExchange":"NASDAQ","calculationPrice":"close","open":249.5,"openTime":1572615000544,"close":255.82,"closeTime":1572638400572,"high":255.93,"low":249.16,"latestPrice":255.82,"latestSource":"Close","latestTime":"November 1, 2019","latestUpdate":1572638400572,"latestVolume":38139225,"iexRealtimePrice":null,
最佳答案
完整的演示程序已经过真实 token 测试,您可以在下面复制粘贴完整运行代码
在示例代码中,我已删除 token ,您必须将其添加回去
实际响应中的json字符串是“quote
”,而您的问题是“stat
”
您必须在布局之前检查响应字符串
当前使用的quote
是photos[index].data["quote"]["iexRealtimePrice"]
来自网址的真实json字符串响应
{"AAPL":{"quote":{"symbol":"AAPL","companyName":"Apple, Inc.","primaryExchange":"NASDAQ","calculationPrice":"close","open":265.69,"openTime":1574260200209,"close":263.19,"closeTime":1574283600212,"high":266.083,"low":260.4,"latestPrice":263.19,"latestSource":"Close","latestTime":"November 20, 2019","latestUpdate":1574283600212,"latestVolume":26015446,"iexRealtimePrice":262.83,"iexRealtimeSize":19,"iexLastUpdated":1574283604924,"delayedPrice":263.19,"delayedPriceTime":1574283600212,"extendedPrice":263.35,"extendedChange":0.16,"extendedChangePercent":0.00061,"extendedPriceTime":1574384397682,"previousClose":266.29,"previousVolume":19069597,"change":-3.1,"changePercent":-0.01164,"volume":26015446,"iexMarketPercent":0.015005278018297284,"iexVolume":390369,"avgTotalVolume":24440833,"iexBidPrice":0,"iexBidSize":0,"iexAskPrice":0,"iexAskSize":0,"marketCap":1169424231300,"peRatio":22.05,"week52High":268,"week52Low":142,"ytdChange":0.674594,"lastTradeTime":1574283604924,"isUSMarketOpen":false}},"FB":{"quote":{"symbol":"FB","companyName":"Facebook, Inc.","primaryExchange":"NASDAQ","calculationPrice":"close","open":198.58,"openTime":1574260200212,"close":197.51,"closeTime":1574283600333,"high":199.59,"low":195.43,"latestPrice":197.51,"latestSource":"Close","latestTime":"November 20, 2019","latestUpdate":1574283600333,"latestVolume":11999607,"iexRealtimePrice":197.5,"iexRealtimeSize":100,"iexLastUpdated":1574283599989,"delayedPrice":197.5,"delayedPriceTime":1574283599989,"extendedPrice":196.5,"extendedChange":-1.01,"extendedChangePercent":-0.00511,"extendedPriceTime":1574384390404,"previousClose":199.32,"previousVolume":19070291,"change":-1.81,"changePercent":-0.00908,"volume":11999607,"iexMarketPercent":0.020256580069663948,"iexVolume":243071,"avgTotalVolume":14362105,"iexBidPrice":0,"iexBidSize":0,"iexAskPrice":0,"iexAskSize":0,"marketCap":563391349700,"peRatio":31.36,"week52High":208.66,"week52Low":123.02,"ytdChange":0.459965,"lastTradeTime":1574283599989,"isUSMarketOpen":false}}}
import 'dart:async';
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
Future<List<Photo>> fetchPhotos(http.Client client) async {
final response =
await client.get('https://cloud.iexapis.com/stable/stock/market/batch?symbols=aapl,fb&types=quote&token=xxx');
/*String response = '''
{"AAPL":
{"stats":{"week52change":0.232986,"week52high":255.93,"week52low":142,"marketcap":1136677331400,"employees":137000,"day200MovingAvg":199.29,"day50MovingAvg":225.28,"float":4436680630.59,"avg10Volume":26482506.4,"avg30Volume":26817874.5,"ttmEPS":11.9342,"ttmDividendRate":3,"companyName":"Apple, Inc."
}
},
"FB":
{"stats":{"week52change":0.1,"week52high":255.93,"week52low":142,"marketcap":1136677331400,"employees":137000,"day200MovingAvg":199.29,"day50MovingAvg":225.28,"float":4436680630.59,"avg10Volume":26482506.4,"avg30Volume":26817874.5,"ttmEPS":11.9342,"ttmDividendRate":3,"companyName":"Apple, Inc."
}
}
}
''';*/
// Use the compute function to run parsePhotos in a separate isolate.
return compute(parsePhotos, response.body);
}
// A function that converts a response body into a List<Photo>.
List<Photo> parsePhotos(String responseBody) {
//final parsed = json.decode(responseBody).cast<Map<String, dynamic>>();
//return parsed.map<Photo>((json) => Photo.fromJson(json)).toList();
dynamic Obj = json.decode(responseBody);
print(Obj.length);
List<Photo> photoList = [];
Obj.forEach((k, v) => photoList.add(Photo(k, v)));
return photoList;
}
class Photo {
String symbol;
dynamic data;
Photo(this.symbol, this.data);
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
final appTitle = 'Isolate Demo';
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title),
),
body: FutureBuilder<List<Photo>>(
future: fetchPhotos(http.Client()),
builder: (context, snapshot) {
if (snapshot.hasError) print(snapshot.error);
return snapshot.hasData
? PhotosList(photos: snapshot.data)
: Center(child: CircularProgressIndicator());
},
),
);
}
}
class PhotosList extends StatelessWidget {
final List<Photo> photos;
PhotosList({Key key, this.photos}) : super(key: key);
@override
Widget build(BuildContext context) {
return GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
),
itemCount: photos.length,
itemBuilder: (context, index) {
return ListTile(
leading: Icon(Icons.album),
title: Text(photos[index].symbol),
subtitle: Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}'),
);
},
);
}
}
关于flutter - Flutter:如何获取JSON嵌套Map方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58849949/
我想了解 Ruby 方法 methods() 是如何工作的。 我尝试使用“ruby 方法”在 Google 上搜索,但这不是我需要的。 我也看过 ruby-doc.org,但我没有找到这种方法。
Test 方法 对指定的字符串执行一个正则表达式搜索,并返回一个 Boolean 值指示是否找到匹配的模式。 object.Test(string) 参数 object 必选项。总是一个
Replace 方法 替换在正则表达式查找中找到的文本。 object.Replace(string1, string2) 参数 object 必选项。总是一个 RegExp 对象的名称。
Raise 方法 生成运行时错误 object.Raise(number, source, description, helpfile, helpcontext) 参数 object 应为
Execute 方法 对指定的字符串执行正则表达式搜索。 object.Execute(string) 参数 object 必选项。总是一个 RegExp 对象的名称。 string
Clear 方法 清除 Err 对象的所有属性设置。 object.Clear object 应为 Err 对象的名称。 说明 在错误处理后,使用 Clear 显式地清除 Err 对象。此
CopyFile 方法 将一个或多个文件从某位置复制到另一位置。 object.CopyFile source, destination[, overwrite] 参数 object 必选
Copy 方法 将指定的文件或文件夹从某位置复制到另一位置。 object.Copy destination[, overwrite] 参数 object 必选项。应为 File 或 F
Close 方法 关闭打开的 TextStream 文件。 object.Close object 应为 TextStream 对象的名称。 说明 下面例子举例说明如何使用 Close 方
BuildPath 方法 向现有路径后添加名称。 object.BuildPath(path, name) 参数 object 必选项。应为 FileSystemObject 对象的名称
GetFolder 方法 返回与指定的路径中某文件夹相应的 Folder 对象。 object.GetFolder(folderspec) 参数 object 必选项。应为 FileSy
GetFileName 方法 返回指定路径(不是指定驱动器路径部分)的最后一个文件或文件夹。 object.GetFileName(pathspec) 参数 object 必选项。应为
GetFile 方法 返回与指定路径中某文件相应的 File 对象。 object.GetFile(filespec) 参数 object 必选项。应为 FileSystemObject
GetExtensionName 方法 返回字符串,该字符串包含路径最后一个组成部分的扩展名。 object.GetExtensionName(path) 参数 object 必选项。应
GetDriveName 方法 返回包含指定路径中驱动器名的字符串。 object.GetDriveName(path) 参数 object 必选项。应为 FileSystemObjec
GetDrive 方法 返回与指定的路径中驱动器相对应的 Drive 对象。 object.GetDrive drivespec 参数 object 必选项。应为 FileSystemO
GetBaseName 方法 返回字符串,其中包含文件的基本名 (不带扩展名), 或者提供的路径说明中的文件夹。 object.GetBaseName(path) 参数 object 必
GetAbsolutePathName 方法 从提供的指定路径中返回完整且含义明确的路径。 object.GetAbsolutePathName(pathspec) 参数 object
FolderExists 方法 如果指定的文件夹存在,则返回 True;否则返回 False。 object.FolderExists(folderspec) 参数 object 必选项
FileExists 方法 如果指定的文件存在返回 True;否则返回 False。 object.FileExists(filespec) 参数 object 必选项。应为 FileS
我是一名优秀的程序员,十分优秀!