Future<String> fetchData() async { // 模拟异步获取数据 await Future.delayed(Duration(seconds: 2)); return "Hello, World!"; } void main() async { String result = await fetchData(); print(result); // 输出:Hello, World! } 在上面的示例中,fetchData函数返回一个Future<String>类型的值。在...
false) 之后 使用的是 return Future.value(true); 那么按下后退按钮后，应用程序将显示黑屏 ...
import 'dart:io'; class CharacterDataReader { Future<String> read() async { final file = File('assets/data/character_data.json'); String data = await file.readAsString(); return data; } } 现在,我尝试将读取的值分配给一个名为data的字符串,并使用以下命令在另一个类中将其json.decode()...
/// /// 返回一个 `Future<String>`,当文件内容被读取后,该Future将完成并返回字符串。 Future<String> readAsString({Encoding encoding = utf8}); 例如: import 'dart:io'; void main() async { var file = File('test.txt'); String contents = await file.readAsString(); print(contents); ...
Future是异步的,如果我们要将异步转同步,那么可以借助asyncawait来完成。 import'dart:async'; test()async{intresult =awaitFuture.delayed(Duration(milliseconds:2000), () {returnFuture.value(123); }); print('t3:'+DateTime.now().toString()); ...
Future<T?> get<T>( String path, { Map<String, dynamic>? queryParameters, Map<String, dynamic>? headers, }) async { try { // RequestOptions options = RequestOptions(); Options options = Options(); if (headers != null) { options.headers = headers; } Response<T> response = await cli...
class NewPage extends StatelessWidget {final String data;NewPage({required this.data});@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: Text('New Page'),),body: Center(child: Text('Data received: $data'),),);}}// 在跳转时传递参数MaterialPageRoute newPage...
Future<Map<String,dynamic>> post(Stringpath, [Map<String,dynamic> form])async{return_channel.invokeMethod("post", {'path': path,'body': form}).then((result) {returnnewMap<String,dynamic>.from(result); }).catchError((_) =>null); ...
Future sendReceive(SendPort sendPort, String url) { ReceivePort receivePort =ReceivePort(); sendPort.send([url, receivePort.sendPort]); // 接收到返回值,返回给调用者 return receivePort.first; } 当然Flutter中封装了compute,可以方便的使用,譬如在其它isolate中解析大的json。