Flutter Dio 的一个可以参照的封装

import 'dart:io';
import 'package:dio/dio.dart';
import 'package:flutter_easyloading/flutter_easyloading.dart';
import 'package:home_framework/utils/cookie_manager.dart';

enum HttpMethod {
  GET,
  PUT,
  POST,
  PATCH,
  DELETE,
  UPLOAD,
}

class HttpUtil {
  static Dio _dioInstance;
  static Dio getDioInstance() {
    if (_dioInstance == null) {
      _dioInstance = Dio();
      _dioInstance.interceptors.add(CookieManager.instance);
      // _dioInstance.interceptors.add(
      //   InterceptorsWrapper(onRequest: (options, handler) {
      //     print('报告老王，小王看上了新的网红：' + options.path);
      //     return handler.next(options);
      //   }, onResponse: (response, handler) {
      //     print('报告老王，小王收到了新网红的回复：' + response.statusMessage);
      //     //throw new Exception('你死心吧！');
      //     handler.next(response);
      //   }, onError: (DioError e, handler) {
      //     print('报告老王，小王被网红喷啦！' + e.message);
      //     return handler.next(e);
      //   }),
      // );
    }

    return _dioInstance;
  }

  // static void setCookie(String cookie) {
  //   _dioInstance.options.headers['Cookie'] = cookie;
  // }

  // static void clearCookie() {
  //   _dioInstance.options.headers['Cookie'] = null;
  // }

  static Future get(String url,
      {Map<String, dynamic> queryParams, CancelToken cancelToken}) async {
    return await sendRequest(HttpMethod.GET, url,
        queryParams: queryParams, cancelToken: cancelToken);
  }

  static Future put(String url,
      {Map<String, dynamic> queryParams, dynamic data}) async {
    return await sendRequest(HttpMethod.PUT, url,
        queryParams: queryParams, data: data);
  }

  static Future post(String url,
      {Map<String, dynamic> queryParams,
      dynamic data,
      CancelToken cancelToken}) async {
    return await sendRequest(HttpMethod.POST, url,
        queryParams: queryParams, data: data, cancelToken: cancelToken);
  }

  static Future patch(String url,
      {Map<String, dynamic> queryParams, dynamic data}) async {
    return await sendRequest(HttpMethod.PATCH, url,
        queryParams: queryParams, data: data);
  }

  static Future delete(String url,
      {Map<String, dynamic> queryParams, dynamic data}) async {
    return await sendRequest(HttpMethod.DELETE, url,
        queryParams: queryParams, data: data);
  }

  static Future uploadSingle(String url, String fileKey, File file,
      {Map<String, dynamic> queryParams}) async {
    FormData formData = FormData.fromMap({
      fileKey: await MultipartFile.fromFile(file.path),
    });
    return await sendRequest(HttpMethod.POST, url,
        queryParams: queryParams, data: formData);
  }

  static Future download(
    String url,
    String savePath, {
    Map<String, dynamic> queryParams,
    CancelToken cancelToken,
    dynamic data,
    Options options,
    void Function(int, int) onReceiveProgress,
  }) async {
    try {
      return await _dioInstance.download(
        url,
        savePath,
        queryParameters: queryParams,
        cancelToken: cancelToken,
        onReceiveProgress: onReceiveProgress,
      );
    } on DioError catch (e) {
      if (CancelToken.isCancel(e)) {
        EasyLoading.showInfo('下载已取消！');
      } else {
        if (e.response != null) {
          _handleErrorResponse(e.response);
        } else {
          EasyLoading.showError(e.message);
        }
      }
    } on Exception catch (e) {
      EasyLoading.showError(e.toString());
    }
  }

  static Future sendRequest(HttpMethod method, String url,
      {Map<String, dynamic> queryParams,
      dynamic data,
      CancelToken cancelToken}) async {
    try {
      switch (method) {
        case HttpMethod.GET:
          return await HttpUtil.getDioInstance()
              .get(url, queryParameters: queryParams, cancelToken: cancelToken);
        case HttpMethod.PUT:
          return await HttpUtil.getDioInstance().put(url,
              queryParameters: queryParams,
              data: data,
              cancelToken: cancelToken);
        case HttpMethod.POST:
          return await HttpUtil.getDioInstance().post(url,
              queryParameters: queryParams,
              data: data,
              cancelToken: cancelToken);
        case HttpMethod.PATCH:
          return await HttpUtil.getDioInstance().patch(url,
              queryParameters: queryParams,
              data: data,
              cancelToken: cancelToken);
        case HttpMethod.DELETE:
          return await HttpUtil.getDioInstance().delete(url,
              queryParameters: queryParams,
              data: data,
              cancelToken: cancelToken);
        default:
          EasyLoading.showError('请求方式错误');
      }
    } on DioError catch (e) {
      if (CancelToken.isCancel(e)) {
        EasyLoading.showInfo('领导喊你回去改 Bug 啦！');
      } else {
        if (e.response != null) {
          _handleErrorResponse(e.response);
        } else {
          EasyLoading.showError(e.message);
        }
      }
    } on Exception catch (e) {
      EasyLoading.showError(e.toString());
    }

    return null;
  }

  static void _handleErrorResponse(Response response) {
    switch (response.statusCode) {
      case 401:
        EasyLoading.showError('验票失败!');
        break;
      case 403:
        EasyLoading.showError('无权限访问!');
        break;
      case 404:
        EasyLoading.showError('404未找到!');
        break;
      case 500:
      case 502:
        EasyLoading.showError('服务器内部错误!');
        break;
      default:
        EasyLoading.showError(response.statusMessage);
    }
  }
}