这是比http库更强大的库哦

https://pub.dev/packages/dio
https://github.com/flutterchina/dio/blob/master/README-ZH.md

将http文章中的例子改造成dio

import 'package:flutter/material.dart';
import 'package:dio/dio.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage2(),
    );
  }
}

class MyHomePage2 extends StatefulWidget {
  @override
  _MyHomePage2State createState() => _MyHomePage2State();
}

class _MyHomePage2State extends State<MyHomePage2> {
  String _getMsg = '';
  String _postMsg = '';
  String _getRealMsg = '';

  _getData() async {
    try {
      Response response = await Dio()
          .get("http://rap2.taobao.org:38080/app/mock/253219/apiget");
      print(response);
      setState(() {
        _getMsg = response.data["msg"];
      });
    } catch (e) {
      print(e);
    }
  }

  _getRealData() async {
    try {
      Response response =
          await Dio().get("http://a.itying.com/api/productlist");
      print(response);
      setState(() {
        _getRealMsg = response.data.toString();
      });
    } catch (e) {
      print(e);
    }
  }

  _postData() async {
    try {
      Response response = await Dio().post(
          "http://rap2.taobao.org:38080/app/mock/253219/apipost",
          data: {"name": "abc", "color": "blue"});
      print(response);
      setState(() {
        _postMsg = response.data['name'];
      });
    } catch (e) {
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("DIO网络请求"),
      ),
      body: SingleChildScrollView(
        child: Column(
          children: <Widget>[
            Row(
              children: <Widget>[
                RaisedButton(child: Text('get'), onPressed: _getData),
                SizedBox(
                  width: 20,
                ),
                Text(_getMsg)
              ],
            ),
            Row(
              children: <Widget>[
                RaisedButton(child: Text('post'), onPressed: _postData),
                SizedBox(
                  width: 20,
                ),
                Text(_postMsg)
              ],
            ),
            RaisedButton(
                child: Text("get请求个真实数据http://a.itying.com/api/productlist"),
                onPressed: _getRealData),
            SizedBox(
              width: 20,
            ),
            Text(_getRealMsg)
          ],
        ),
      ),
    );
  }
}

除了这些简单用法,dio还可以

• 下载文件 response = await dio.download("https://www.google.com/", "./xx.html");
• 流方式接受响应数据

Response<ResponseBody> rs = await Dio().get<ResponseBody>(url,
  options: Options(responseType: ResponseType.stream), //设置接收类型为stream
);
print(rs.data.stream); //响应流

• 自定义请求头
• 请求拦截

dio.interceptors.add(InterceptorsWrapper(
    onRequest:(RequestOptions options) async {
     // 在请求被发送之前做一些事情
     return options; //continue
     // 如果你想完成请求并返回一些自定义数据，可以返回一个`Response`对象或返回`dio.resolve(data)`。
     // 这样请求将会被终止，上层then会被调用，then中返回的数据将是你的自定义数据data.
     //
     // 如果你想终止请求并触发一个错误,你可以返回一个`DioError`对象，或返回`dio.reject(errMsg)`，
     // 这样请求将被中止并触发异常，上层catchError会被调用。
    },
    onResponse:(Response response) async {
     // 在返回响应数据之前做一些预处理
     return response; // continue
    },
    onError: (DioError e) async {
      // 当请求失败时做一些预处理
     return e;//continue
    }
));

• 以二进制数组的方式接收响应数据
• 发送 FormData
• 通过FormData上传多个文件
• 监听发送(上传)数据进度
• 以流的形式提交二进制数据

详见参考文档.

官方实例:

https://github.com/flutterchina/dio/blob/master/example/options.dart

import 'dart:io';
import 'package:dio/dio.dart';

main() async {
  var dio = Dio(BaseOptions(
    baseUrl: "http://httpbin.org/",
    connectTimeout: 5000,
    receiveTimeout: 100000,
    // 5s
    headers: {
      HttpHeaders.userAgentHeader: "dio",
      "api": "1.0.0",
    },
    contentType: Headers.jsonContentType,
    // Transform the response data to a String encoded with UTF8.
    // The default value is [ResponseType.JSON].
    responseType: ResponseType.plain,
  ));

  Response response;

  response = await dio.get("/get");
  print(response.data);

  Response<Map> responseMap = await dio.get(
    "/get",
    // Transform response data to Json Map
    options: Options(responseType: ResponseType.json),
  );
  print(responseMap.data);
  response = await dio.post(
    "/post",
    data: {
      "id": 8,
      "info": {"name": "wendux", "age": 25}
    },
    // Send data with "application/x-www-form-urlencoded" format
    options: Options(
      contentType: Headers.formUrlEncodedContentType,
    ),
  );
  print(response.data);

  response = await dio.request(
    "/",
    options: RequestOptions(baseUrl: "https://baidu.com"),
  );
  print(response.data);
}