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Flutter 将Dio请求转发原生网络库的实现方案

作者:且听风吟zzz

这篇文章主要介绍了Flutter 将Dio请求转发原生网络库,需要注意添加NativeNetInterceptor,如果有多个拦截器,例如LogInterceptors等等,需要将NativeNetInterceptor放到最后,需要的朋友可以参考下

背景

首先看到标题,相信大家已经血压飙升了,既然都用了Flutter,怎么还用原生的网络库呢?这不是多此一举么。emmmmm,当我看到这个需求的时候一样恼火。但因为我们项目中使用的Dio库不支持查询DNSSSL等所需时间(至少我没找到),而Okhttp却可以。因此,不得以只能借助原生网络库去实现此功能。

实现方案

既然必须要去实现,那摆在面前的问题就是如何去实现了。最简单粗暴的一个方式,就是通过建立一个Flutter Channel将网络请求的所有信息传到原生,但脑补一波后,发现实现起来太过麻烦,一堆header,body,data等信息都需要自己组装,并且致命的是需要改动现有项目的请求方式。因此为了避免项目大改,最后看中了Dio提供的interceptors(拦截器)功能,在拦截器中,我们可以对网络请求进行拦截,拦截后再通过FlutterChannel发给原生进行网络请求。这样既避免了项目改动,也省去了数据组装,很容易的达到了目标。

实现步骤

class NativeNetInterceptor extends Interceptor {
  final Dio dio;
  final NativeNetOptions options;
  NativeNetInterceptor({
    required this.dio,
    NativeNetOptions? options,
  }) : options = options ?? NativeNetOptions();
  @override
  void onRequest(
      RequestOptions options, RequestInterceptorHandler handler) async {
    try {
      Response response = await NativeNet.sendRequestToNative(options);
      return handler.resolve(response, true);
    } catch (e) {
      if (e.runtimeType == DioError) {
        return handler.reject(e as DioError);
      } else {
        // TODO:如果担心原生有问题,可打开下方注释。
        // handler.next(options);
        rethrow;
      }
    }
  }
}
class NativeNet {
  static const MethodChannel _channel = MethodChannel('nativeNet');

  static Future<Response> sendRequestToNative(RequestOptions options) async {
    final String url = options.baseUrl + options.path;
    Map channelParams = _getChannelParams(
      url,
      options.method,
      queryParameters: options.queryParameters,
      data: options.data,
      header: options.headers,
      timeoutInterval: options.connectTimeout,
    );
    return await _sendRequestToNative(options, channelParams);
  }

  static Future<Response> _sendRequestToNative(
      RequestOptions options, Map params) async {
    final Map nativeResponse =
        await _channel.invokeMapMethod('net', params) ?? {};
    final Response response = Response(requestOptions: options);
    if (nativeResponse.containsKey('headers')) {
      final Map nativeResponseHaders = nativeResponse['headers'];
      nativeResponseHaders.forEach((key, value) {
        response.headers.set(key, value);
      });
    }
    response.statusCode = nativeResponse['statusCode'] ?? -1;
    response.statusMessage = nativeResponse['statusMessage'] ?? '无message';
    if (Platform.isAndroid) {
      if (nativeResponse.containsKey('data')) {
        String jsonData = nativeResponse['data'];
        try {
          Map<String, dynamic> data = convert.jsonDecode(jsonData);
          response.data = data;
        } on FormatException catch (e) {
          ///转换异常后手动构造一下
          debugPrint("Http FormatException");
          Map map = {};
          map["data"] = jsonData;
          response.data = map;
        }
      } else {
        response.data = {};
      }
    } else {
      Map<String, dynamic> data =
          Map<String, dynamic>.from(nativeResponse['data'] ?? {});
      response.data = data;
    }

    if (nativeResponse.containsKey('error')) {
      //网络请求失败
      Map? errorData = nativeResponse['error'];
      throw DioError(
          requestOptions: options, response: response, error: errorData);
    }
    return response;
  }
  static Map<String, dynamic> _getChannelParams(
    String url,
    String method, {
    Map<String, dynamic>? queryParameters,
    Map<String, dynamic>? data,
    Map<String, dynamic>? header,
    num? timeoutInterval,
    num? retryCount,
  }) {
    Map<String, dynamic> channelParams = {
      'url': url,
      'method': method,
    };
    if (queryParameters != null) {
      channelParams['queryParameters'] = queryParameters;
    }
    if (data != null) {
      channelParams['data'] = data;
    }
    if (header != null) {
      channelParams['header'] = header;
    }
    if (retryCount != null) {
      channelParams['retryCount'] = retryCount;
    }
    if (timeoutInterval != null) {
      channelParams['timeoutInterval'] = timeoutInterval;
    }
    return channelParams;
  }
}
class NativeNetPlugin : FlutterPlugin, MethodCallHandler {
    /// The MethodChannel that will the communication between Flutter and native Android
    ///
    /// This local reference serves to register the plugin with the Flutter Engine and unregister it
    /// when the Flutter Engine is detached from the Activity
    private lateinit var channel: MethodChannel
    private var gson: Gson = Gson()
    private val mTag = "Android NativeNetPlugin"

    override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
        channel = MethodChannel(flutterPluginBinding.binaryMessenger, "nativeNet")
        channel.setMethodCallHandler(this)
    }

    override fun onMethodCall(@NonNull call: MethodCall, @NonNull result: Result) {
        if (call.method == "net") {
            val channelParams = call.arguments as Map<String, Any>

            var method = ""
            if (channelParams.containsKey("method")) {
                method = channelParams["method"] as String
            }

            var url = ""
            if (channelParams.containsKey("url")) {
                url = channelParams["url"] as String
            }

            var header = HashMap<String, String>()
            if (channelParams.containsKey("header")) {
                header = channelParams["header"] as HashMap<String, String>
            }
            val headers = HttpHeaders()
            headers.headersMap = getMapValueForLinkedHashMap(header)

            // params
            var queryParameters = HashMap<String, String>()
            if (channelParams.containsKey("queryParameters")) {
                queryParameters = channelParams["queryParameters"] as HashMap<String, String>
            }
            //post body
            var data = HashMap<String, Any>()
            if (channelParams.containsKey("data")) {
                data = channelParams["data"] as HashMap<String, Any>
            }

            //超时时间
            var timeoutInterval: Int = 1000 * 15
            if (channelParams.containsKey("timeoutInterval")) {
                timeoutInterval = channelParams["timeoutInterval"] as Int
            }
            val mTimeOut =
                Timeout(timeoutInterval, timeoutInterval, timeoutInterval, TimeUnit.MILLISECONDS)

            //重试次数
            var retryCount = 0
            if (channelParams.containsKey("retryCount")) {
                retryCount = channelParams["retryCount"] as Int
            }

            when (method) {
                "POST" -> {
                    ...
                    //请求成功/失败后调用此方法,
                    result.success(dealResponse(response))
                    
                }
                "GET" -> {
                   ...
                }

                "DELETE" -> {
                   ...
                }

                "PUT" -> {
                   ...
                }

                "HEAD" -> {
                   ...
                }
                else -> {
                    result.notImplemented()
                }
            }
        } else {
            result.notImplemented()
        }
    }

    private fun dealResponse(
        response: Response<String>
    ): Map<String, Any?> {
        val map = HashMap<String, Any?>()

        if (BuildConfig.DEBUG) {
            Log.e(mTag, "dealResponse isSuccessful: ${response.code()}")
            Log.e(mTag, "dealResponse code: ${response.code()}")
            Log.e(mTag, "dealResponse message: ${response.message()}")
            Log.e(mTag, "dealResponse body: ${response.body()}")
            Log.e(mTag, "dealResponse headers: ${response.headers()}")
        }

        map["statusCode"] = response.code()

        response.message()?.let {
            map["statusMessage"] = it
        } ?: let {
            map["statusMessage"] = ""
        }

        response.body()?.let {
            map["data"] = it
        } ?: let {
            map["data"] = ""
        }

        response.headers()?.let {
            map["headers"] = it.toMap()
        } ?: let {
            map["headers"] = HashMap<String, Any>()
        }

        if (response.code() != 200) {
            //失败
            val errorMap = HashMap<String, Any?>()
            response.exception?.let {
                errorMap["code"] = response.code()
                errorMap["domain"] = it.toString()
                errorMap["description"] = it.message
            } ?: let {
                errorMap["code"] = response.code()
                errorMap["domain"] = map["statusMessage"]
                errorMap["description"] = "HttpException"
            }
            map["error"] = errorMap
        }
        return map
    }

    //map 转 LinkedHashMap
    private fun getMapValueForLinkedHashMap(dataMap: Map<String, String>): LinkedHashMap<String, String> {
        val returnMap: LinkedHashMap<String, String> = LinkedHashMap()
        if (dataMap.isNullOrEmpty()) {
            return returnMap
        }
        val iterator = dataMap.keys.iterator()
        while (iterator.hasNext()) {
            val objKey = iterator.next()
            val objValue = dataMap[objKey]
            returnMap[objKey] = objValue.toString()
        }
        return returnMap
    }

    override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
        channel.setMethodCallHandler(null)
    }
}

4.最后调用dio.interceptors.add(NativeNetInterceptor(dio: dio));将我们写好的NativeNetInterceptor加入Dio拦截器。

交互协议

Request(Flutter To Native)

{
    "url": "https://www.baidu.com", // 必传 请求地址
    "method": "GET", //必传 请求方式 GET POST HEAD PUT DELETE
    "queryParameters":{}, //可选 query参数
    "data":{}, //可选 body参数
    "header":{}, //可选 请求头
    "timeoutInterval":15000, //可选 (毫秒) 链接超时时常
    "retryCount": 0 //可选 重试次数,默认0
}

Response(Native To Flutter)

// native返回 成功
{
    "data":{}, //接口原始返回内容
    "headers":{}, //返回头
    "statusCode":200, //http状态码
    "statusMessage":"请求成功" //http状态码对应文案
}
// native返回 失败
{
    "data":{}, //接口原始返回内容
    "headers":{}, //返回头
    "statusCode":404, //http状态码
    "statusMessage":"找不到对象", //http状态码对应文案
    "error":{
    "code":-3001, //错误码
    "domain":"URLDmain", // 错误大分类
    "description":"错误详情" // 错误详情
    }
}

注意点

添加NativeNetInterceptor,如果有多个拦截器,例如LogInterceptors等等,需要将NativeNetInterceptor放到最后。

到此这篇关于Flutter 将Dio请求转发原生网络库的文章就介绍到这了,更多相关Flutter Dio请求转发原生网络库内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家!

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