详解Flutter中网络框架dio的二次封装

// 定义两个函数
typedef Success<T> = Function(T data);  请求数据data为obj对象
typedef SuccessList<T> = Function(List<T> data); // 请求数据data为[]数组

/// 响应数据头数据统一管理
class BaseRes<T> {
  int? code;// 状态码
  String? message; // 状态码说明
  T? data; // 渲染数据

  BaseRes({this.code, this.message, this.data});

  factory BaseRes.fromJSON(json) {
    // json 渲染json数据
    try {
      if (json["code"] != null) {
        try {
         code = json["code"];
        } catch (e) {
          code = -1;
        }
      } else {
        return BaseRes(code: -1, message: "服务器开小差了~", data: null);
      }
      return BaseRes(
          code: json["code"] ?? -1,
          message: json["message"],
          data: BeanFactory.generateOBJ<T>(json["data"]));
    } catch (e) {
      return BaseRes(code: -1, message: "服务器开小差了~", data: null);
    }
  }
}

/// 实体bean转化工厂类
class BeanFactory {
  static T? generateOBJ<T>(json) {
    //T.toString() 类名
    try {
      switch (T.toString()) {
        case "int":
          return json;
        case "bool":
          return json;
        case "String":
          return json;
        default:
          // 实体类序列化
          return TestBean.fORMJson(json) as T;
      }
    } catch (e) {
      return null;
    }
  }
}

/// 测试bean
class TestBean {
  String? msg;
  bool? isSelector;
  TestBean(this.msg,this.isSelector);

  TestBean.fromJson(dynamic json) {
    msg = json["msg"];
    isSelector = json["isSelector"];
  }

  Map<String, dynamic> toJson() {
    var map = <String, dynamic>{};
    map["msg"] = msg;
    map["isSelector"] = isSelector;
    return map;
  }
}

/// dio配置类
class DioManager {

  static const baseUrl = "https://xxx"; // 正式环境

  static DioManager instance = DioManager._internal();
  Dio? _dio;
  final Map<String, dynamic> _headers = {};


  // 单例 私有化构造初始化dio
  DioManager._internal() {
    if (_dio == null) {
      BaseOptions options = BaseOptions(
          baseUrl: baseUrl,
          contentType: Headers.jsonContentType,
          responseType: ResponseType.json,
          receiveDataWhenStatusError: false,
          connectTimeout: _connectTimeout,
          receiveTimeout: _receiveTimeout,
          headers: _headers);
      _dio = Dio(options);

/// 正式环境拦截日志打印
if (!const bool.fromEnvironment("dart.vm.product")) {
  _dio?.interceptors
      .add(LogInterceptor(requestBody: true, responseBody: true));
}


Future<Uint8List> imageToBytes(String imageUrl) async {
  var response = await _dio?.get(imageUrl,
      options: Options(responseType: ResponseType.bytes));
  return Uint8List.fromList(response?.data);
}

get header => _headers;

/// 更新header
updateHeader() {
  _dio?.options.headers = _headers;
}

/// 请求，返回的渲染数据 T
/// method：请求方法，NWMethod.GET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<T>(Method method, String path,
    {String? baseUrl,
      Map<String, dynamic>? params,
      data,
      ProgressCallback? onSendProgress, // 上传数据进度
      ProgressCallback? onReceiveProgress, // 接受数据进度
      Success<T>? success,
      Function(ErrorRes)? error}) async {
  try {
    var connectivityResult = await (Connectivity().checkConnectivity());

    if (connectivityResult == ConnectivityResult.none) {
      if (error != null) {
        error(ErrorRes(code: -9, message: "网络异常~,请检查您的网络状态!"));
      }
      return;
    }
    _setBaseUrl(baseUrl); // 动态设置baseUrl 
    Response? response = await _dio?.request(
      path,
      queryParameters: params,
      data: data,
      onSendProgress: onSendProgress,
      onReceiveProgress: onReceiveProgress,
      options: Options(method: methodValues[method]),
    );
    if (response != null) {
      BaseRes entity = BaseRes<T>.fromJson(response.data);
      // 对象数据结构
      if (entity.code == 200 && entity.data != null) {
        if (success != null) success(entity.data);
      } else {
        if (error != null) {
          error(ErrorRes(code: entity.code, message: entity.message));
        }
      }
    } else {
      if (error != null) error(ErrorRes(code: -1, message: "未知错误"));
    }
  } on DioError catch (e) {
    if (error != null) error(createErrorEntity(e));
  }
}

typedef Success<T> = Function(T data); // 定义一个函数 请求成功回调
typedef Error = Function(ErrorRes errorRes); // 请求失败统一回调
typedef SuccessList<T> = Function(List<T> data); // 请求数据data为[]集合

/// 通用调用接口类
class Http {
  // 私有构造
  Http._internal();
  static Http instance = Http._internal();
 
  /// get请求
  /// baseUrl 切换baseUrl
  /// params 参数
  /// success 请求对象成功回调
  /// successList 请求列表成功回调
  /// error 错误回调
  /// [isList] 请求的数据是否为List列表 默认对象
  /// [isList]=true 请求data数据为[]list列表
  void get<T>(String url,
      {String? baseUrl,
        Map<String, dynamic>? params,
        Success<T>? success,
        SuccessList<T>? successList,
        Error? error,
        bool isList = false}) {
    if (isList) {
      _requestList<T>(Method.get, url,
          baseUrl: baseUrl, params: params, success: successList, error: error);
    } else {
      _request<T>(Method.get, url,
          baseUrl: baseUrl, params: params, success: success, error: error);
    }
  }
  
/// post请求
/// baseUrl 切换baseUrl
/// params 参数
/// data 上传表单数据 formData
/// success 请求对象成功回调
/// successList 请求列表成功回调
/// error 错误回调
/// [isList] 请求的数据是否为List列表 默认对象
/// [isList]=true 请求data数据为[]list列表
void post<T>(String url,
    {String? baseUrl,
      Map<String, dynamic>? params,
      required data,
      Success<T>? success,
      SuccessList<T>? successList,
      Error? error,
      bool isList = false}) {
  if (isList) {
    _requestList<T>(Method.post, url,
        data: data,
        baseUrl: baseUrl,
        params: params,
        success: successList,
        error: error);
  } else {
    _request<T>(Method.post, url,
        data: data,
        baseUrl: baseUrl,
        params: params,
        success: success,
        error: error);
  }
}

mixin LoginModel {
// get请求
loadCode(
  String value, {
  required Success<String> success,
  required Error error,
}) {
  Http.instance.get(api.loadxxx,
      params: {"key": value}, success: success, error: error);
}
}