最近在看flutter，自己搭了环境跑了一下demo，如果问题，还请指正；另外：utf8，jsonDecode需要小写，不然Flutter中文网的http案列会报错。
在http请求时，本地用的node.js跑的后台。但是始终不能请求不到数据，127.0.0.1，或者localhost都不行，查阅到一篇博客，juejin.cn/post/1
了解到Android底层是Linux内核，它本身就是一个操作系统，所以我们在模拟器的浏览器中输入127.0.0.1所代表的是Android模拟器（Android虚拟机），并不是你的电脑，所以在模拟器中会出错。在Android操作系统中，将本地电脑映射为10.0.2.2，所以只需要改成10.0.2.2就ok了。
搞了半天，node配置跨域等等还是不行。
第二天早上问了下公司的安卓同事，建议换成本地有线网络的IP。大功告成！
代码如下参考Flutter中文网
import 'dart:convert';
import 'dart:io';
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
@override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
var _ipAddress = 'Unknown';
_getIPAddress() async {
var url = 'http://192.168.56.1:3000/abc';
// var url = 'https://httpbin.org/ip';
var httpClient = new HttpClient();
String result;
try {
var request = await httpClient.getUrl(Uri.parse(url));
var response = await request.close();
if (response.statusCode == 200) {
var json = await response.transform(utf8.decoder).join();
var data = jsonDecode(json);
print(data);
result = data['message'];
} else {
result =
'Error getting IP address:\nHttp status ${response.statusCode}';
}
} catch (exception) {
print(111);
result = '1233Failed getting IP address';
}
// If the widget was removed from the tree while the message was in flight,
// we want to discard the reply rather than calling setState to update our
// non-existent appearance.
if (!mounted) return;
setState(() {
_ipAddress = result;
});
}
@override
Widget build(BuildContext context) {
var spacer = new SizedBox(height: 32.0);
return new Scaffold(
body: new Center(
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Text('Your current IP address is:'),
new Text('$_ipAddress.'),
spacer,
new RaisedButton(
onPressed: _getIPAddress,
child: new Text('Get IP address'),
),
],
),
),
);
}
}
