Flutter封装dio网络请求

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

/*
    * 封装 restful 请求
    * 
    * GET、POST、DELETE、PATCH
    * 主要作用为统一处理相关事务：
    *  - 统一处理请求前缀；
    *  - 统一打印请求信息；
    *  - 统一打印响应信息；
    *  - 统一打印报错信息；
*/
class HttpUtils {

    /// global dio object
    static Dio dio;

    /// default options
    static const String API_PREFIX = 'https://toeii.com/api/v1';
    static const int CONNECT_TIMEOUT = 10000;
    static const int RECEIVE_TIMEOUT = 3000;

    /// http request methods
    static const String GET = 'get';
    static const String POST = 'post';
    static const String PUT = 'put';
    static const String PATCH = 'patch';
    static const String DELETE = 'delete';

    /// request method
    static Future<Map> request (
        String url, 
        { data, method }) async {

        data = data ?? {};
        method = method ?? 'GET';

        /// restful 请求处理   
        /// /gysw/search/hist/:user_id        user_id=27
        /// 最终生成 url 为     /gysw/search/hist/27
        data.forEach((key, value) {
        if (url.indexOf(key) != -1) {
            url = url.replaceAll(':$key', value.toString());
        }
        });

        /// 打印请求相关信息：请求地址、请求方式、请求参数
        print('请求地址：【' + method + '  ' + url + '】');
        print('请求参数：' + data.toString());

        Dio dio = createInstance();
        var result;

        try {
        Response response = await dio.request(url, data: data, options: new Options(method: method));

        result = response.data;

        /// 打印响应相关信息
        print('响应数据：' + response.toString());
        } on DioError catch (e) {
        /// 打印请求失败相关信息
        print('请求出错：' + e.toString());
        } 

        return result;
    }

    /// 创建 dio 实例对象
    static Dio createInstance () {
        if (dio == null) {
        /// 全局属性：请求前缀、连接超时时间、响应超时时间
        Options options = new Options(
            baseUrl: API_PREFIX,
            connectTimeout: CONNECT_TIMEOUT,
            receiveTimeout: RECEIVE_TIMEOUT,
        );

        dio = new Dio(options);
        }

        return dio;
    }

    /// 清空 dio 对象
    static clear () {
        dio = null;
    }

}

import 'dart:async';
import '../utils/HttpUtils.dart';

    // GET 请求
    // 返回的结果直接就是 json 格式
    // 要使用 await，必须在方法名后面加上 async
    _handleGetShelf () async {
    var result = await HttpUtils.request(
        '/gysw/shelf', 
        method: HttpUtils.GET,
        data: {
        'id': 1,
        }
    );
    }


    // POST 请求
    _handleAddShelf () async {
    var result = await HttpUtils.request(
        '/gysw/shelf', 
        method: HttpUtils.POST,
        data: {
        'id': 1,
        }
    );
    }

    // PUT 请求
    _handleEditShelf () async{
    var result = await HttpUtils.request(
        '/gysw/shelf/:id', 
        method: HttpUtils.PUT,
        data: {
        'id': 1,
        }
    );
    }

    // DELETE 请求
    _handleDelShelf () async {
    var result = await HttpUtils.request(
        '/gysw/shelf/:id', 
        method: HttpUtils.DELETE,
        data: {
        'id': 1,
        }
    );
}