编辑添加dio解析示例和解析图片
Response response;
Dio dio = new Dio();
response = await dio.get("http://yoursite");
print(response);
print(response.data.toString());
List<Payload> payload = payloadFromJson(response.data);
print({payload[0].tableNo});
假设 dio 已经返回正确的 json 字符串是
String jsonString = '[{"table_no": "1"},{"table_no": "2"},{"table_no": "3"}]';
第 1 步：使用有效负载类解析 jsonString
List<Payload> payload = payloadFromJson(jsonString);
有效载荷类
List<Payload> payloadFromJson(String str) =>
List<Payload>.from(json.decode(str).map((x) => Payload.fromJson(x)));
String payloadToJson(List<Payload> data) =>
json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Payload {
String tableNo;
Payload({
this.tableNo,
});
factory Payload.fromJson(Map<String, dynamic> json) => Payload(
tableNo: json["table_no"],
);
Map<String, dynamic> toJson() => {
"table_no": tableNo,
};
}
第 2 步：将此有效负载传输到所需的 DropdownMenuItem 映射
for (var i = 0; i < payload.length; i++) {
_myJson.add({'id': payload[i].tableNo, 'name': payload[i].tableNo});
}
第 3 步：填充 DropdownMenuItem
DropdownButton<String>(
isDense: true,
hint: Text("${payload[0].tableNo}"),
value: _mySelection,
onChanged: (String Value) {
setState(() {
_mySelection = Value;
});
print(_mySelection);
},
items: _myJson.map((Map map) {
return DropdownMenuItem<String>(
value: map["id"].toString(),
child: Text(
map["name"],
),
);
}).toList(),
),
完整代码
import 'package:flutter/material.dart';
import 'dart:convert';
List<Payload> payloadFromJson(String str) =>
List<Payload>.from(json.decode(str).map((x) => Payload.fromJson(x)));
String payloadToJson(List<Payload> data) =>
json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Payload {
String tableNo;
Payload({
this.tableNo,
});
factory Payload.fromJson(Map<String, dynamic> json) => Payload(
tableNo: json["table_no"],
);
Map<String, dynamic> toJson() => {
"table_no": tableNo,
};
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
String jsonString = '[{"table_no": "1"},{"table_no": "2"},{"table_no": "3"}]';
List<Payload> payload = payloadFromJson(jsonString);
List<Map> _myJson = [];
class _MyHomePageState extends State<MyHomePage> {
String _mySelection;
@override
void initState() {
for (var i = 0; i < payload.length; i++) {
_myJson.add({'id': payload[i].tableNo, 'name': payload[i].tableNo});
}
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(
children: <Widget>[
Container(
height: 500.0,
child: Center(
child: DropdownButton<String>(
isDense: true,
hint: Text("${payload[0].tableNo}"),
value: _mySelection,
onChanged: (String Value) {
setState(() {
_mySelection = Value;
});
print(_mySelection);
},
items: _myJson.map((Map map) {
return DropdownMenuItem<String>(
value: map["id"].toString(),
child: Text(
map["name"],
),
);
}).toList(),
),
),
),
],
),
),
);
}
}
