瞎扯

写app离不开网络请求,没有网络请求没有灵魂
不多bb

HttpClient

import 'dart:io';

var httpClient = new HttpClient();

getData() async {
  var httpClient = new HttpClient();
  var uri = new Uri.http(
      'example.com', '/path1/path2', {'param1': '42', 'param2': 'foo'});
  var request = await httpClient.getUrl(uri);
  var response = await request.close();
  var responseBody = await response.transform(UTF8.decoder).join();
}

上面是官方的例子.

请求来说很简单.

但是有两个东西是新的.
async await

async

很简单,异步的意思.相当于new了一个线程

await

这个呢,可以理解为携程

也就是等待这一行走完返回结果的意思.

所以在这个方法里面,每一步都是很直观的写出来的,不用担心异步回调的问题.

是不是很简单呢.

 _getIPAddress() async {
    var url = 'https://httpbin.org/ip';// 请求地址
    var httpClient = new HttpClient();

    String result;
    try { //可能出错
      var request = await httpClient.getUrl(Uri.parse(url));//发起请求
      var response = await request.close();//关闭流,得到结果
      if (response.statusCode == HttpStatus.OK) {
        var json = await response.transform(UTF8.decoder).join();//转换为json
        var data = JSON.decode(json);//json解析
        result = data['origin']; //得到对象
      } else {
        result =
            'Error getting IP address:\nHttp status ${response.statusCode}'; //接口出错
      }
    } catch (exception) {
      result = 'Failed getting IP address';//产生异常
    }

    // 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;//生命周期控制

    setState(() { //更新UI
      _ipAddress = result;
    });
  }

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