YTKNetwork 原始碼閱讀(二)-一次POST請求的完整歷程

weixin_33866037發表於2017-03-11
原始碼

寫在前面:

  1. 這篇文寫了什麼？
    用YTKNetwork走一次網路請求的完整歷程。

  2. 我能看到哪些內容？
    以下是YTKNetwork官方文件的原話，說的是相比 AFNetworking，YTKNetwork 提供了以下更高階的功能，其中，後面打對號的部分是在這個歷程中能看到的風景。

    • 支援按時間快取網路請求內容 ✅
    • 支援按版本號快取網路請求內容 ✅
    • 支援統一設定伺服器和 CDN 的地址 ✅
    • 支援檢查返回 JSON 內容的合法性 ✅
    • 支援檔案的斷點續傳
    • 支援 block 和 delegate 兩種模式的回撥方式 ✅
    • 支援批量的網路請求傳送，並統一設定它們的回撥（實現在 YTKBatchRequest 類中）
    • 支援方便地設定有相互依賴的網路請求的傳送，例如：傳送請求 A，根據請求 A 的結果，選擇性的傳送請求 B 和 C，再根據 B 和 C 的結果，選擇性的傳送請求 D。（實現在 YTKChainRequest 類中）
    • 支援網路請求 URL 的 filter，可以統一為網路請求加上一些引數，或者修改一些路徑。 ✅
    • 定義了一套外掛機制，可以很方便地為 YTKNetwork 增加功能。猿題庫官方現在提供了一個外掛，可以在某些網路請求發起時，在介面上顯示“正在載入”的 HUD。

旅程前的準備:(這一部分是YTKNetwork的基礎用法，可以略過不看)

  1. 設定baseUrl
    //支援統一設定伺服器和 CDN 的地址 ✅
    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    YTKNetworkConfig *config = [YTKNetworkConfig sharedConfig];
    config.baseUrl = @"http://yuantiku.com";
    }

  2. 建立請求類

     // UserInfoRequest.m
 @interface UserInfoRequest () {
     NSString *_uid;
 }
 @end

 @implementation UserInfoRequest

 - (instancetype)initWithUid:(NSString *)uid {
     self = [super init];
     if (self) {
         _uid = uid;
     }
     return self;
 }

 - (NSString *)requestUrl {
     return @"/OwoccAppAPI/api/user";
 }

 - (YTKRequestMethod)requestMethod {
     return YTKRequestMethodPost;
 }

 - (id)requestArgument {
     return @{
             @"uid": _uid,
             };
 }

啟程

  1. 開始一個新請求

     NSString *uid = @"1002";
 //1. 建立一個請求例項，uid是引數。這個請求是post。
 UserInfoRequest *userInfoReq = [[UserInfoRequest alloc] initWithUid:uid];
 //2. 便利請求方法，選擇了block回撥的方式。點進這個方法，去看看它的實現。
 [userInfoReq startWithCompletionBlockWithSuccess:^(YTKBaseRequest *request) {
     NSLog(@"請求成功,返回資料:%@",request.responseString);
 } failure:^(YTKBaseRequest *request) {
     NSLog(@"請求失敗");
 }];

  2. 請求便利方法

     - (void)startWithCompletionBlockWithSuccess:(void (^)(YTKBaseRequest *request))success
                                     failure:(void (^)(YTKBaseRequest *request))failure {
     //1. 設定好成功和失敗的回撥。請看下                                   
     [self setCompletionBlockWithSuccess:success failure:failure];
     //2. 開始
     [self start];
 }

 - (void)setCompletionBlockWithSuccess:(void (^)(YTKBaseRequest *request))success
                             failure:(void (^)(YTKBaseRequest *request))failure {
     self.successCompletionBlock = success;
     self.failureCompletionBlock = failure;
 }

  3. 開始請求，首先看能不能從快取拿資料

     - (void)start {
     //1. 如果忽略快取，直接開始請求。如果不忽略，往下 走
     if (self.ignoreCache) {
         [super start];
         return;
     }

     //2. 支援按時間快取網路請求內容 ✅。如果沒有設定cacheTimeInSeconds，直接開始請求。如果設定了，往下 走
     if ([self cacheTimeInSeconds] < 0) {
         [super start];
         return;
     }

     //3. 支援按版本號快取網路請求內容✅。
     long long cacheVersionFileContent = [self cacheVersionFileContent]; //已經快取內容的版本號
     //如果cacheVersionFileContent和這個請求的版本號不同的話，直接開始請求。如果相同，往下 走
     if (cacheVersionFileContent != [self cacheVersion]) {
         [super start];
         return;
     }

     //4. 檢視快取是否存在。如果不存在，直接開始請求。如果存在，往下 走。快取在沙盒中的路徑是: /Library/LazyRequestCache/POST+完整連結地址+引數+應用版本號+敏感內容
     NSString *path = [self cacheFilePath];
     NSFileManager *fileManager = [NSFileManager defaultManager];
     if (![fileManager fileExistsAtPath:path isDirectory:nil]) {
         [super start];
         return;
     }

     //5. 檢查快取檔案最後一次修改時間到現在的間隔。如果間隔大於我們設定的cacheTimeInSeconds直接開始請求。如果小於，往下 走
     int seconds = [self cacheFileDuration:path];
     if (seconds < 0 || seconds > [self cacheTimeInSeconds]) {
         [super start];
         return;
     }

     //6. 從快取中拿資料。如果為nil，直接開始請求。如果不為nil，往下 走
     _cacheJson = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
     if (_cacheJson == nil) {
         [super start];
         return;
     }

     //7. 如果走到這裡了，說明沒有走介面，直接從快取拿的資料。
      _dataFromCache = YES;//第一步
     [self requestCompleteFilter];//第二步
     //第三步：走請求完成的回撥。支援 block 和 delegate 兩種模式的回撥方式 ✅
     YTKRequest *strongSelf = self;
     [strongSelf.delegate requestFinished:strongSelf];
     if (strongSelf.successCompletionBlock) {
         strongSelf.successCompletionBlock(strongSelf);
     }
     [strongSelf clearCompletionBlock];//把成功和失敗的block置為nil
 }

  4. 請求真正開始(沒能從快取拿資料)

     /// append self to request queue
 - (void)start {
     [self toggleAccessoriesWillStartCallBack];//不用看
     //command 設計模式：把request傳給接收器(這裡就是YTKNetworkAgent)
     [[YTKNetworkAgent sharedInstance] addRequest:self];
 }

  5. YTKNetworkAgent的addRequest:方法

     - (void)addRequest:(YTKBaseRequest *)request {
     //1. 獲取請求方法，這裡是POST
     YTKRequestMethod method = [request requestMethod];
     //2. 組合完整連結地址: baseUrl + requestUrl
     //支援網路請求 URL 的 filter，可以統一為網路請求加上一些引數，或者修改一些路徑。✅
     NSString *url = [self buildRequestUrl:request];
     //3. 請求引數
     id param = request.requestArgument;
     //4.
     AFConstructingBlock constructingBlock = [request constructingBodyBlock];
     //5. 請求序列化型別
     if (request.requestSerializerType == YTKRequestSerializerTypeHTTP) {
         _manager.requestSerializer = [AFHTTPRequestSerializer serializer];
     } else if (request.requestSerializerType == YTKRequestSerializerTypeJSON) {
         _manager.requestSerializer = [AFJSONRequestSerializer serializer];
     }
     //6. 請求超時時間。可以自定義，預設60s
     _manager.requestSerializer.timeoutInterval = [request requestTimeoutInterval];

     //7. 如果需要的話，設定訪問伺服器的username和password
     NSArray *authorizationHeaderFieldArray = [request requestAuthorizationHeaderFieldArray];
     if (authorizationHeaderFieldArray != nil) {
         [_manager.requestSerializer setAuthorizationHeaderFieldWithUsername:(NSString *)authorizationHeaderFieldArray.firstObject
                                                                 password:(NSString *)authorizationHeaderFieldArray.lastObject];
     }
     
     //8. 如果需要的話，配置一些請求頭的資訊
     NSDictionary *headerFieldValueDictionary = [request requestHeaderFieldValueDictionary];
     if (headerFieldValueDictionary != nil) {
         for (id httpHeaderField in headerFieldValueDictionary.allKeys) {
             id value = headerFieldValueDictionary[httpHeaderField];
             if ([httpHeaderField isKindOfClass:[NSString class]] && [value isKindOfClass:[NSString class]]) {
                 [_manager.requestSerializer setValue:(NSString *)value forHTTPHeaderField:(NSString *)httpHeaderField];
             } else {
                 YTKLog(@"Error, class of key/value in headerFieldValueDictionary should be NSString.");
             }
         }
     }

     //9. 自定義url。
     NSURLRequest *customUrlRequest= [request buildCustomUrlRequest];
     if (customUrlRequest) {
         //注意: 如果自定義了url，會忽略請求類的requestUrl, requestArgument, requestMethod, requestSerializerType
         AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:customUrlRequest];
         [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
             [self handleRequestResult:operation];
         } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
             [self handleRequestResult:operation];
         }];
         request.requestOperation = operation;
         operation.responseSerializer = _manager.responseSerializer;
         [_manager.operationQueue addOperation:operation];
     } else {
         //GET方法，我們這裡的示例是POST，看下
         if (method == YTKRequestMethodGet) {
             if (request.resumableDownloadPath) {
                 // add parameters to URL;
                 NSString *filteredUrl = [YTKNetworkPrivate urlStringWithOriginUrlString:url appendParameters:param];

                 NSURLRequest *requestUrl = [NSURLRequest requestWithURL:[NSURL URLWithString:filteredUrl]];
                 AFDownloadRequestOperation *operation = [[AFDownloadRequestOperation alloc] initWithRequest:requestUrl targetPath:request.resumableDownloadPath shouldResume:YES];
                 [operation setProgressiveDownloadProgressBlock:request.resumableDownloadProgressBlock];
                 [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
                     [self handleRequestResult:operation];
                 }                                failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                     [self handleRequestResult:operation];
                 }];
                 request.requestOperation = operation;
                 [_manager.operationQueue addOperation:operation];
             } else {
                 request.requestOperation = [_manager GET:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
                     [self handleRequestResult:operation];
                 }                                failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                     [self handleRequestResult:operation];
                 }];
             }
         } else if (method == YTKRequestMethodPost) {
             //10. 開始請求，用的是AFNetworking
             if (constructingBlock != nil) {
                 request.requestOperation = [_manager POST:url parameters:param constructingBodyWithBlock:constructingBlock
                                                 success:^(AFHTTPRequestOperation *operation, id responseObject) {
                                                     [self handleRequestResult:operation];
                                                 } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                             [self handleRequestResult:operation];
                         }];
             } else {
                 request.requestOperation = [_manager POST:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
                     [self handleRequestResult:operation];
                 }                                 failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                     //12. 請求完成，處理請求的結果.(11請看下面)
                     [self handleRequestResult:operation];
                 }];
             }
         } else if (method == YTKRequestMethodHead) {
             request.requestOperation = [_manager HEAD:url parameters:param success:^(AFHTTPRequestOperation *operation) {
                 [self handleRequestResult:operation];
             }                                 failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                 [self handleRequestResult:operation];
             }];
         } else if (method == YTKRequestMethodPut) {
             request.requestOperation = [_manager PUT:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
                 [self handleRequestResult:operation];
             }                                failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                 [self handleRequestResult:operation];
             }];
         } else if (method == YTKRequestMethodDelete) {
             request.requestOperation = [_manager DELETE:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
                 [self handleRequestResult:operation];
             }                                   failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                 [self handleRequestResult:operation];
             }];
         } else if (method == YTKRequestMethodPatch) {
             request.requestOperation = [_manager PATCH:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
                 [self handleRequestResult:operation];
             } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                 [self handleRequestResult:operation];
             }];
         } else {
             YTKLog(@"Error, unsupport method type");
             return;
         }
     }

     YTKLog(@"Add request: %@", NSStringFromClass([request class]));
     //11. 把request存到_requestsRecord裡面
     [self addOperation:request];
 }

  6. 處理請求的下來的資料handleRequestResult:

     - (void)handleRequestResult:(AFHTTPRequestOperation *)operation {
     NSString *key = [self requestHashKey:operation];
     //1. 把request從_requestsRecord拿出來
     YTKBaseRequest *request = _requestsRecord[key];
     YTKLog(@"Finished Request: %@", NSStringFromClass([request class]));
     //2. 如果request存在，接著往下走
     if (request) {
         // 支援檢查返回 JSON 內容的合法性 ✅
         BOOL succeed = [self checkResult:request];
         if (succeed) {
             //成功,走成功的回撥
             [request toggleAccessoriesWillStopCallBack];
             [request requestCompleteFilter];
             if (request.delegate != nil) {
                 [request.delegate requestFinished:request];
             }
             if (request.successCompletionBlock) {
                 request.successCompletionBlock(request);
             }
             [request toggleAccessoriesDidStopCallBack];
         } else {
             //失敗,走失敗的回撥
             YTKLog(@"Request %@ failed, status code = %ld",
                     NSStringFromClass([request class]), (long)request.responseStatusCode);
             [request toggleAccessoriesWillStopCallBack];
             [request requestFailedFilter];
             if (request.delegate != nil) {
                 [request.delegate requestFailed:request];
             }
             if (request.failureCompletionBlock) {
                 request.failureCompletionBlock(request);
             }
             [request toggleAccessoriesDidStopCallBack];
         }
     }
     //3. 把request從requestRecord移除出去
     [self removeOperation:operation];
     //4. 把成功和失敗的block回撥置為nil
     [request clearCompletionBlock];
 }

YTKNetwork 原始碼閱讀(一)-整體框架

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