一个用于展示 Flutter Future.wait() 用法的代码

flutter_future_wait_demo.dart

main(List<String> args) async {
  print('hello2');
  var t1 = DateTime.now().millisecondsSinceEpoch;
  // replace callFuns() with callFuns2()
  await callFuns();
  var t2 = DateTime.now().millisecondsSinceEpoch;
  print('cost ${t2 - t1}');
}

// cost 5015
Future callFuns() async {
  var r = await fun1();
  var r2 = await fun2();
  print('r = $r');
  print('r2 = $r2');
}

// cost 3008
Future callFuns2() async {
  //var r = await fun1();
  //var r2 = await fun2();
  var rArr = await Future.wait([fun1(), fun2()]);
  var r = rArr[0];
  var r2 = rArr[1];
  print('r = $r');
  print('r2 = $r2');
}

Future<String> fun1() {
  return Future.delayed(Duration(seconds: 2), () {
    return "future 1";
  });
}

Future<String> fun2() {
  return Future.delayed(Duration(seconds: 3), () {
    return "future 2";
  });
}