APP开发或多或少都要用到http网络请求，在Flutter中http请求的使用方式非常简单，只需在引入http库，设置url等必要参数后，调用http.get()或者http.post()方法即可。

Get方式请求

首先需要在 pubspec.yaml 中添加依赖：

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dependencies:
  ...
  http: '>=0.11.3+16'

然后调用http.get()方法即可：

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import 'package:http/http.dart' as http;
[...]
  loadData() async {
    String dataURL = "https://api.bmob.cn/1/classes/book/";
    http.Response response = await http.get(dataURL);
    print("response body : ${response.body}");
  }
}

设置http请求头 header：

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loadData() async {
  String dataUrl = "https://api.bmob.cn/1/classes/book/";
  Map<String, String> map = new Map();
  map["Content-Type"] = "application/json";
  map["X-Bmob-Application-Id"] = "ce30565639d0fb10cd925b5b024c3408";
  map["X-Bmob-REST-API-Key"] = "4057ff07b1bec5590fb4ff0a16141938";
  http.Response response = await http.get(dataUrl, headers: map);
  print("${response.body}");
}

请求成功后刷新界面：

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loadData() async {
  String dataUrl = "https://api.bmob.cn/1/classes/book/";
  Map<String, String> map = new Map();
  map["Content-Type"] = "application/json";
  map["X-Bmob-Application-Id"] = "ce30565639d0fb10cd925b5b024c3408";
  map["X-Bmob-REST-API-Key"] = "4057ff07b1bec5590fb4ff0a16141938";
  http.Response response = await http.get(dataUrl, headers: map);
  print("${response.body}");

  //解析数据
  BookResponse baseResponse = new BookResponse(response.body);

  //通知界面更新状态，刷新界面
  setState(() {
      _books = baseResponse.data;
  });
}

Post方式请求

将get方式中的http.get() 方法改为 http.post() 方法，并添加参数body即可：

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void _postData(Book book) async {
    String dataUrl = "https://api.bmob.cn/1/classes/book/";

    //设置请求头
    Map<String, String> map = new Map();
    map["Content-Type"] = "application/json";
    map["X-Bmob-Application-Id"] = "ce30565639d0fb10cd925b5b024c3408";
    map["X-Bmob-REST-API-Key"] = "4057ff07b1bec5590fb4ff0a16141938";
    try {

    //使用Post方式
      http.Response response = await http.post(dataUrl, headers: map, body: json.encode(book));
      print("${response.body}");
    } on Exception catch (e) {
      print("exception $e");
      SnackBar mSnackBar = new SnackBar(content: new Text("上传数据错误"));
      Scaffold.of(context).showSnackBar(mSnackBar);
   }
}

更多用法参考官方示例