如何使用 Flutter 通过 class 名称或 ID 从 url 获取数据？

Question

As you see in the title of the question, I need to fetch data from URL by class name or id in Flutter. There is some data I haven't got its JSON data, and I need them to display on my app. I could fetch data using the code in the below, but I can't fetch any data by class name or id because I don't know what I need to use. Please help me

class _MyHomePageState extends State<MyHomePage> {
  String stringResponse;

  Future fetcData() async {
    http.Response response;
    response = await http.get("www.example.com"); //Consider that the URL has just a string such as "This is a string."
    if (response.statusCode == 200) {
      setState(() {
        stringResponse = response.body;
      });
    } else {
      
    }
  }

  @override
  void initState() {
    // TODO: implement initState
    fetcData();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Http request"),
      ),
      body: Center(
        child: Text(stringResponse.toString()),
      ),
    );
  }
}

Answer 1

here is package http package .

here is a complete method to get a response.

     HttpClient client = new HttpClient()
          ..badCertificateCallback =
              ((X509Certificate cert, String host, int port) => true);


     return client.getUrl(Uri.parse(url)).then((HttpClientRequest request) {
      request.headers.set('content-type', 'application/json-patch+json');
      request.headers.set('accept', 'application/json');
      var response = request.close().timeout(new Duration(seconds: 5));
      return response;
    }).then((HttpClientResponse response) {
      var result = response.transform(utf8.decoder).join();
      return result;
    }).catchError((onError) {
      var result = onError.transform(utf8.decoder).join();
      return result;
    });
  

Answer 2

This error is because not your phone issue, Maybe that's also an issue, But follow my code;

Following my local.properties file

sdk.dir=/Users/gloify/Library/Android/sdk
flutter.sdk=/Users/gloify/Downloads/flutter
flutter.buildMode=debug
flutter.versionName=1.0.0
flutter.versionCode=1
flutter.minSdkVersion=27
flutter.targetSdkVersion=33
flutter.compileSdkVersion=33

and in app level build.gradle,

defaultConfig {
    
    applicationId "com.example.emito"
    minSdkVersion localProperties.getProperty('flutter.minSdkVersion').toInteger()
   targetSdkVersion localProperties.getProperty('flutter.targetSdkVersion').toInteger()
    versionCode flutterVersionCode.toInteger()
    versionName flutterVersionName
}

if you are setting localProperties.getProperty('flutter.minSdkVersion').toInteger() as localProperties.getProperty('flutter.compileSdkVersion').toInteger()

then this type of error will occur. Make sure your default config.

That's it Thank you