Flutter如何将数据列表保存到本地存储 [英] Flutter How to save list of data to local Storage
问题描述
我正在开发电影发现应用程序,因此需要将正在播放的电影列表保存在本地存储中以供离线使用,所以我该怎么办
Future> getNowPlayingMovies()async {
final String nowPlaying =
' https://api.themoviedb.org/ 3 / tv / airing_today?api_key = '+
'$ myapikey'+
'& page ='+
'1';
I am developing movie discovering app on flutter and I need to save the list of now playing movies on local storage for offline use and so how can I do that Future> getNowPlayingMovies() async { final String nowPlaying = 'https://api.themoviedb.org/3/tv/airing_today?api_key=' + '$myapikey' + '&page=' + '1';
var httpClient = new HttpClient();
try {
// Make the call
var request = await httpClient.getUrl(Uri.parse(nowPlaying));
var response = await request.close();
if (response.statusCode == HttpStatus.OK) {
var jsonResponse = await response.transform(utf8.decoder).join();
// Decode the json response
var data = jsonDecode(jsonResponse);
// Get the result list
List results = data["results"];
print(results);
// Get the Movie list
List<moviemodel> movieList = createNowPlayingMovieList(results);
// Print the results.
return movieList;
} else {
print("Failed http call.");
}
} catch (exception) {
print(exception.toString());
}
return null;}
List<moviemodel> createNowPlayingMovieList(List data) {
List<Searchmodel> list = new List();
for (int i = 0; i < data.length; i++) {
var id = data[i]["id"];
String title = data[i]["name"];
String posterPath = data[i]["poster_path"];
String mediatype = data[i]["media_type"];
moviemodel movie = new moviemodel(id, title, posterPath, mediatype);
list.add(movie);
}
return list; }
List<Widget> createNowPlayingMovieCardItem(
List<moviemodel> movies, BuildContext context) {
// Children list for the list.
List<Widget> listElementWidgetList = new List<Widget>();
if (movies != null) {
var lengthOfList = movies.length;
for (int i = 0; i < lengthOfList; i++) {
Searchmodel movie = movies[i];
// Image URL
var imageURL = "https://image.tmdb.org/t/p/w500/" + movie.posterPath;
// List item created with an image of the poster
var listItem = new Padding(
padding: const EdgeInsets.all(8.0),
child: new Container(
width: 105.0,
height: 155.0,
child: new Column(
children: <Widget>[
new GestureDetector(
onTap: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (_) => new Detail(movie.id)),
);
},
child: new Container(
width: 105.0,
height: 155.0,
child: new ClipRRect(
borderRadius: new BorderRadius.circular(7.0),
child: new Hero(
tag: movie.title,
child: new FadeInImage.memoryNetwork(
placeholder: kTransparentImage,
image: imageURL,
fit: BoxFit.cover,
),
),
),
decoration: new BoxDecoration(boxShadow: [
new BoxShadow(
color: Colors.black12,
blurRadius: 10.0,
offset: new Offset(0.0, 10.0)),
]),
),
),
new Padding(
padding: const EdgeInsets.only(top: 18.0),
child: new Text(
movie.title,
maxLines: 2,
),
)
],
),
),
);
;
listElementWidgetList.add(listItem);
}
} else {
print("no movie search");
}
return listElementWidgetList;}
谢谢!
推荐答案
使用 path_provider
:
- 找到正确的本地路径:
Future get _localPath async {
final directory = await getApplicationDocumentsDirectory();
return directory.path;
}
- 创建对文件位置的引用
Future get _localFile async {
final path = await _localPath;
return File('$path/yourfile.txt');
}
- 将数据写入文件:
Future writeCounter(int counter) async {
final file = await _localFile;
// Write the file
return file.writeAsString('blah bla blah');
}
- 从文件中读取数据:
Future readCounter() async {
try {
final file = await _localFile;
// Read the file
String contents = await file.readAsString();
return int.parse(contents);
} catch (e) {
// If we encounter an error, return 0
return 0;
}
}
如果打印内容
=等等等等
If you print contents
= "blah blah blah"
文档: https://flutter.io/cookbook/persistence/reading-writing-files/
并且文件有一个许多方法可以帮助您,结帐:
https://docs.flutter.io/flutter/dart-io/File-class.html
这篇关于Flutter如何将数据列表保存到本地存储的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!