Flutter每分钟自动刷新JSON

本文介绍了Flutter每分钟自动刷新JSON的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我已经在网上搜索了自动刷新小部件，并为Flutter自动刷新了将来的JSON，但结果似乎都是下拉刷新.

I have searched the web for auto refresh widgets and auto refresh future JSON for Flutter but the results all seem to be for pull down refresh.

我需要的就像是一个我可以调用的函数，所说的函数每重复一分钟.

What I need is like a function that I can call and every minute that said function repeats.

我知道我必须整合类似的东西:

I know I have to integrate something like:

var future = new Future.delayed(const Duration(milliseconds: 10), TracksWidget());

但是我不确定该放在哪里.

However I am not sure where I need to put it.

import 'dart:async'; import 'dart:convert'; import 'package:flutter/material.dart'; import 'package:http/http.dart' as http; import '../model/track.dart'; class TracksWidget extends StatefulWidget { @override _TracksWidgetState createState() => _TracksWidgetState(); } class _TracksWidgetState extends State<TracksWidget> { Future<Track> track; @override Widget build(BuildContext context) { double c_width = MediaQuery.of(context).size.width; return new FutureBuilder<Track>( future: track, builder: (context, snapshot) { if (snapshot.hasData) { Track track = snapshot.data; return new Container( padding: const EdgeInsets.all(16.0), width: c_width, child: new Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ Imagework(track.imageurl, width:200.0, height: 200.0,fit: BoxFit.cover), Text(track.title), Text(track.artist), ]), ); } else if (snapshot.hasError) { return Text("${snapshot.error}"); } //By default, show a loading spinner. return CircularProgressIndicator(); }, ); } @override void initState() { super.initState(); track = fetchTrack(); } Future<Track> fetchTrack() async { final response = await http.get('139.59.108.222:2199/rpc/drn1/streaminfo.get'); if (response.statusCode == 200) { // If the call to the server was successful, parse the JSON. var responseJson = json.decode(response.body); // assume there is only one track to display // SO question mentioned 'display current track' var track = responseJson['data'] .map((musicFileJson) => Track.fromJson(musicFileJson['track'])) .first; return track; } else { // If that call was not successful, throw an error. throw Exception('Failed to load post'); } } }

推荐答案

我发现最简单的方法是使用Timer函数.

The simplest way to do this I have found is to use the Timer function.

如果将计时器放入initState，则它将在应用程序启动时启动. 在下面的代码中，计时器将每5秒调用一次addValue()方法，这将使该值每次增加1.只需记住在完成计时器后就将其丢弃.

If you put the timer into initState it will start when the the app is started. In the code below, the timer will call the addValue() method every 5 seconds which increases the value by one each time. Just remember to dispose of the timer when you have finished with it.

class MyHomePage extends StatefulWidget { MyHomePage({Key key, this.title}) : super(key: key); final String title; @override _MyHomePageState createState() => _MyHomePageState(); } class _MyHomePageState extends State<MyHomePage> { Timer timer; int counter = 0; @override void initState() { super.initState(); timer = Timer.periodic(Duration(seconds: 5), (Timer t) => addValue()); } void addValue() { setState(() { counter++; }); } @override void dispose() { timer?.cancel(); super.dispose(); } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text(widget.title), ), body: Center( child: Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ Text(counter.toString()) ], ), ), ); } }