FlutterDio中怎么实现二次封装，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

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目录：

DioManager：Dio辅助类NWMethod：请求方法，get、post等  NWApi：大家都知道  EntityFactory：json转换辅助工厂，把json转为T  BaseEntity：数据基类，返回的参数为 {“code”: 0, “message”: “”, “data”: {}}  BaseListEntity：数据基类2，返回的参数为 {“code”: 0, “message”: “”, “data”: []}  ErrorEntity：请求报错基类，{“code”: 0, “message”: “”}

EntityFactory：

class EntityFactory { static T generateOBJ(json) {  if (json == null) {   return null;  }//可以在这里加入任何需要并且可以转换的类型，例如下面//  else if (T.toString() == "LoginEntity") {//   return LoginEntity.fromJson(json) as T;//  }  else {   return json as T;  } }}

BaseEntity：

class BaseEntity { int code; String message; T data; BaseEntity({this.code, this.message, this.data}); factory BaseEntity.fromJson(json) {  return BaseEntity(   code: json["code"],   message: json["msg"],   // data值需要经过工厂转换为我们传进来的类型   data: EntityFactory.generateOBJ(json["data"]),  ); }}

BaseListEntity：

class BaseListEntity { int code; String message; List data; BaseListEntity({this.code, this.message, this.data}); factory BaseListEntity.fromJson(json) {  List mData = List();  if (json['data'] != null) {   //遍历data并转换为我们传进来的类型   (json['data'] as List).forEach((v) {    mData.add(EntityFactory.generateOBJ(v));   });  }  return BaseListEntity(   code: json["code"],   message: json["msg"],   data: mData,  ); } }

ErrorEntity：

class ErrorEntity { int code; String message; ErrorEntity({this.code, this.message});}

NWApi：

class NWApi { static final baseApi = "https://easy-mock.bookset.io/mock/5dfae67d4946c20a50841fa7/example/"; static final loginPath = "user/login";//接口返回：{"code": int, "message": "String", "data": {"account": "String", "password": "String"}} static final queryListPath = "/query/list";//接口返回：{"code": ing, "message": "String", "data": [int, int, String, int, String, int]} static final queryListJsonPath = "/query/listjson";//接口返回：{"code": int, "message": "String", "data": [{"account": "String", "password": "String"}， {"account": "String", "password": "String"}]}}

NWMethod：

enum NWMethod { GET, POST, DELETE, PUT}//使用：NWMethodValues[NWMethod.POST]const NWMethodValues = { NWMethod.GET: "get", NWMethod.POST: "post", NWMethod.DELETE: "delete", NWMethod.PUT: "put"};

下面就可以进行正式的封装了：

第一步是创建Dio的单例辅助类，并初始化Dio和对Dio进行一些全局的参数设置：

import 'package:dio/dio.dart';import 'package:flutter_app/network/NWApi.dart';import 'package:flutter_app/utils/PrintUtil.dart';class DioManager { static final DioManager _shared = DioManager._internal(); factory DioManager() => _shared; Dio dio; DioManager._internal() {  if (dio == null) {   BaseOptions options = BaseOptions(    baseUrl: NWApi.baseApi,    contentType: Headers.jsonContentType,    responseType: ResponseType.json,    receiveDataWhenStatusError: false,    connectTimeout: 30000,    receiveTimeout: 3000,   );   dio = Dio(options);  } }}

第二步对请求进行封装，在我的想法中 {“code”: 0, “message”: “”, “data”: {}} 和 {“code”: 0, “message”: “”, “data”: []} 这两种数据是要分开两个请求方法的：

// 请求，返回参数为 T // method：请求方法，NWMethod.POST等 // path：请求地址 // params：请求参数 // success：请求成功回调 // error：请求失败回调 Future request(NWMethod method, String path, {Map params, Function(T) success, Function(ErrorEntity) error}) async {  try {   Response response = await dio.request(path, queryParameters: params, options: Options(method: NWMethodValues[method]));   if (response != null) {    BaseEntity entity = BaseEntity.fromJson(response.data);    if (entity.code == 0) {     success(entity.data);    } else {     error(ErrorEntity(code: entity.code, message: entity.message));    }   } else {    error(ErrorEntity(code: -1, message: "未知错误"));   }  } on DioError catch(e) {   error(createErrorEntity(e));  } } // 请求，返回参数为 List // method：请求方法，NWMethod.POST等 // path：请求地址 // params：请求参数 // success：请求成功回调 // error：请求失败回调 Future requestList(NWMethod method, String path, {Map params, Function(List) success, Function(ErrorEntity) error}) async {  try {   Response response = await dio.request(path, queryParameters: params, options: Options(method: NWMethodValues[method]));   if (response != null) {    BaseListEntity entity = BaseListEntity.fromJson(response.data);    if (entity.code == 0) {     success(entity.data);    } else {     error(ErrorEntity(code: entity.code, message: entity.message));    }   } else {     error(ErrorEntity(code: -1, message: "未知错误"));   }  } on DioError catch(e) {   error(createErrorEntity(e));  } }

提取请求错误处理方法createErrorEntity：

// 错误信息 ErrorEntity createErrorEntity(DioError error) {  switch (error.type) {   case DioErrorType.CANCEL:{    return ErrorEntity(code: -1, message: "请求取消");   }   break;   case DioErrorType.CONNECT_TIMEOUT:{    return ErrorEntity(code: -1, message: "连接超时");   }   break;   case DioErrorType.SEND_TIMEOUT:{    return ErrorEntity(code: -1, message: "请求超时");   }   break;   case DioErrorType.RECEIVE_TIMEOUT:{    return ErrorEntity(code: -1, message: "响应超时");   }   break;   case DioErrorType.RESPONSE:{    try {     int errCode = error.response.statusCode;     String errMsg = error.response.statusMessage;     return ErrorEntity(code: errCode, message: errMsg);//     switch (errCode) {//      case 400: {//       return ErrorEntity(code: errCode, message: "请求语法错误");//      }//      break;//      case 403: {//       return ErrorEntity(code: errCode, message: "服务器拒绝执行");//      }//      break;//      case 404: {//       return ErrorEntity(code: errCode, message: "无法连接服务器");//      }//      break;//      case 405: {//       return ErrorEntity(code: errCode, message: "请求方法被禁止");//      }//      break;//      case 500: {//       return ErrorEntity(code: errCode, message: "服务器内部错误");//      }//      break;//      case 502: {//       return ErrorEntity(code: errCode, message: "无效的请求");//      }//      break;//      case 503: {//       return ErrorEntity(code: errCode, message: "服务器挂了");//      }//      break;//      case 505: {//       return ErrorEntity(code: errCode, message: "不支持HTTP协议请求");//      }//      break;//      default: {//       return ErrorEntity(code: errCode, message: "未知错误");//      }//     }    } on Exception catch(_) {     return ErrorEntity(code: -1, message: "未知错误");    }   }   break;   default: {    return ErrorEntity(code: -1, message: error.message);   }  } }

完整的 DioManager 类代码：

import 'package:dio/dio.dart';import 'package:flutter_app/network/entity/BaseEntity.dart';import 'package:flutter_app/network/entity/BaseListEntity.dart';import 'package:flutter_app/network/entity/EntityFactory.dart';import 'package:flutter_app/network/entity/ErrorEntity.dart';import 'package:flutter_app/network/NWApi.dart';import 'package:flutter_app/network/NWMethod.dart';class DioManager { static final DioManager _shared = DioManager._internal(); factory DioManager() => _shared; Dio dio; DioManager._internal() {  if (dio == null) {   BaseOptions options = BaseOptions(    baseUrl: NWApi.baseApi,    contentType: Headers.jsonContentType,    responseType: ResponseType.json,    receiveDataWhenStatusError: false,    connectTimeout: 30000,    receiveTimeout: 3000,   );   dio = Dio(options);  } } // 请求，返回参数为 T // method：请求方法，NWMethod.POST等 // path：请求地址 // params：请求参数 // success：请求成功回调 // error：请求失败回调 Future request(NWMethod method, String path, {Map params, Function(T) success, Function(ErrorEntity) error}) async {  try {   Response response = await dio.request(path, queryParameters: params, options: Options(method: NWMethodValues[method]));   if (response != null) {    BaseEntity entity = BaseEntity.fromJson(response.data);    if (entity.code == 0) {     success(entity.data);    } else {     error(ErrorEntity(code: entity.code, message: entity.message));    }   } else {    error(ErrorEntity(code: -1, message: "未知错误"));   }  } on DioError catch(e) {   error(createErrorEntity(e));  } } // 请求，返回参数为 List // method：请求方法，NWMethod.POST等 // path：请求地址 // params：请求参数 // success：请求成功回调 // error：请求失败回调 Future requestList(NWMethod method, String path, {Map params, Function(List) success, Function(ErrorEntity) error}) async {  try {   Response response = await dio.request(path, queryParameters: params, options: Options(method: NWMethodValues[method]));   if (response != null) {    BaseListEntity entity = BaseListEntity.fromJson(response.data);    if (entity.code == 0) {     success(entity.data);    } else {     error(ErrorEntity(code: entity.code, message: entity.message));    }   } else {    error(ErrorEntity(code: -1, message: "未知错误"));   }  } on DioError catch(e) {   error(createErrorEntity(e));  } } // 错误信息 ErrorEntity createErrorEntity(DioError error) {  switch (error.type) {   case DioErrorType.CANCEL:{    return ErrorEntity(code: -1, message: "请求取消");   }   break;   case DioErrorType.CONNECT_TIMEOUT:{    return ErrorEntity(code: -1, message: "连接超时");   }   break;   case DioErrorType.SEND_TIMEOUT:{    return ErrorEntity(code: -1, message: "请求超时");   }   break;   case DioErrorType.RECEIVE_TIMEOUT:{    return ErrorEntity(code: -1, message: "响应超时");   }   break;   case DioErrorType.RESPONSE:{    try {     int errCode = error.response.statusCode;     String errMsg = error.response.statusMessage;     return ErrorEntity(code: "$errCode", message: errMsg);//     switch (errCode) {//      case 400: {//       return ErrorEntity(code: errCode, message: "请求语法错误");//      }//      break;//      case 403: {//       return ErrorEntity(code: errCode, message: "服务器拒绝执行");//      }//      break;//      case 404: {//       return ErrorEntity(code: errCode, message: "无法连接服务器");//      }//      break;//      case 405: {//       return ErrorEntity(code: errCode, message: "请求方法被禁止");//      }//      break;//      case 500: {//       return ErrorEntity(code: errCode, message: "服务器内部错误");//      }//      break;//      case 502: {//       return ErrorEntity(code: errCode, message: "无效的请求");//      }//      break;//      case 503: {//       return ErrorEntity(code: errCode, message: "服务器挂了");//      }//      break;//      case 505: {//       return ErrorEntity(code: errCode, message: "不支持HTTP协议请求");//      }//      break;//      default: {//       return ErrorEntity(code: errCode, message: "未知错误");//      }//     }    } on Exception catch(_) {     return ErrorEntity(code: -1, message: "未知错误");    }   }   break;   default: {    return ErrorEntity(code: -1, message: error.message);   }  } }}

使用：

// 返回 LoginEntityDioManager().request( NWMethod.POST, NWApi.loginPath, params: {"account": "421789838@qq.com", "password": "123456"}, success: (data) {   print("success data = $data"}); }, error: (error) {   print("error code = ${error.code}, massage = ${error.message}"); });// 返回 ListDioManager().requestList( NWMethod.POST, NWApi.queryListJsonPath, params: {"account": "421789838@qq.com", "password": "123456"}, success: (data) {   print("success data = $data"}); }, error: (error) {   print("error code = ${error.code}, massage = ${error.message}"); });

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