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| import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'dart:isolate';
void main() {
runApp(new SampleApp());
}
class SampleApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Sample App',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new SampleAppPage(),
);
}
}
class SampleAppPage extends StatefulWidget {
SampleAppPage({Key key}) : super(key: key);
@override
_SampleAppPageState createState() => new _SampleAppPageState();
}
class _SampleAppPageState extends State<SampleAppPage> {
List widgets = [];
@override
void initState() {
super.initState();
loadData();
}
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("Sample App"),
),
body: new ListView.builder(
itemCount: widgets.length,
itemBuilder: (BuildContext context, int position) {
return getRow(position);
}));
}
Widget getRow(int i) {
return new Padding(
padding: new EdgeInsets.all(10.0),
child: new Text("Row ${widgets[i]["title"]}"));
}
loadData() async {
debugPrint("1");
ReceivePort receivePort = new ReceivePort();
debugPrint("2");
await Isolate.spawn(dataLoader, receivePort.sendPort);
debugPrint("3");
// The 'echo' isolate sends it's SendPort as the first message
SendPort sendPort = await receivePort.first;
debugPrint("4");
List msg = await sendReceive(
sendPort, "https://jsonplaceholder.typicode.com/posts");
debugPrint("5");
setState(() {
debugPrint("6");
widgets = msg;
});
}
// the entry point for the isolate
static dataLoader(SendPort sendPort) async {
debugPrint("7");
// Open the ReceivePort for incoming messages.
ReceivePort port = new ReceivePort();
debugPrint("8");
// Notify any other isolates what port this isolate listens to.
sendPort.send(port.sendPort);
debugPrint("9");
await for (var msg in port) {
debugPrint("10");
String data = msg[0];
SendPort replyTo = msg[1];
String dataURL = data;
debugPrint("14");
http.Response response = await http.get(dataURL);
debugPrint("15");
// Lots of JSON to parse
replyTo.send(json.decode(response.body));
debugPrint("16");
}
}
Future sendReceive(SendPort port, msg) {
debugPrint("11");
ReceivePort response = new ReceivePort();
debugPrint("12");
port.send([msg, response.sendPort]);
debugPrint("13");
return response.first;
}
}
|