AFNetworking 3.0 源碼解析之Serialization
本部分主要的作用:網絡通信資訊序列化/反序列化
一、AFURLRequestSerialization
功能:
負責參數轉換成NSMutableURLRequest類型,進行網絡請求。 1)建構普通請求:格式化請求參數,生成HTTP Header 2)建構multipart請求
類關系:
父類:AFHTTPRequestSerializer,二進制格式(query字元串轉換成二進制) 子類:AFJSONRequestSerializer,Json格式(Json序列化成NSData類型) AFPropertyListRequestSerializer,Plist(一種特殊的XML,解析起來相對容易)
封裝思路:
所有類遵循一個協定AFURLRequestSerialization,協定中一個非必須實作的方法:
- (nullableNSURLRequest*)requestBySerializingRequest:(NSURLRequest*)request
withParameters:(nullableid)parameters
error:(NSError* _Nullable__autoreleasing *)error NS_SWIFT_NOTHROW;
父類AFHTTPRequestSerializer中提供外部調用接口:
- (NSMutableURLRequest*)requestWithMethod:(NSString*)method
URLString:(NSString*)URLString
parameters:(id)parameters
error:(NSError*__autoreleasing*)error
在這個方法中調用協定方法:
mutableRequest = [[selfrequestBySerializingRequest:mutableRequestwithParameters:parameterserror:error]mutableCopy];
而這個方法的實作是父類以及各個子類分别實作。是以,此處self如果是AFHTTPRequestSerializer那麼走AFHTTPRequestSerializer類下的實作,如果是 AFJSONRequestSerializer,那麼走AFJSONRequestSerializer類下的實作。然後再分别實作這個方法不同功能的實作。
下面看一下各個類不同職能分别的實作:
AFURLRequestSerialization中的實作:
- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
withParameters:(id)parameters
error:(NSError *__autoreleasing *)error
{
NSParameterAssert(request);
NSMutableURLRequest *mutableRequest = [requestmutableCopy];
[self.HTTPRequestHeadersenumerateKeysAndObjectsUsingBlock:^(id field,id value, BOOL *__unused stop) {
if (![requestvalueForHTTPHeaderField:field]) {
[mutableRequest setValue:valueforHTTPHeaderField:field];
}
}];
NSString *query =nil;
if (parameters) {
if (self.queryStringSerialization) {
NSError *serializationError;
query = self.queryStringSerialization(request, parameters, &serializationError);
if (serializationError) {
if (error) {
*error = serializationError;
}
returnnil;
}
} else {
switch (self.queryStringSerializationStyle) {
caseAFHTTPRequestQueryStringDefaultStyle:
query = AFQueryStringFromParameters(parameters);
break;
}
}
}
if ([self.HTTPMethodsEncodingParametersInURIcontainsObject:[[request HTTPMethod]uppercaseString]]) { //普通GET,HEAD等,參數直接拼接在url後面用&分開
if (query && query.length >0) {
mutableRequest.URL = [NSURLURLWithString:[[mutableRequest.URLabsoluteString] stringByAppendingFormat:mutableRequest.URL.query ? @"&%@" : @"?%@", query]];
}
} else {
// #2864: an empty string is a valid x-www-form-urlencoded payload
if (!query) {
query = @"";
}
if (![mutableRequestvalueForHTTPHeaderField:@"Content-Type"]) {
[mutableRequest setValue:@"application/x-www-form-urlencoded"forHTTPHeaderField:@"Content-Type"];
}
[mutableRequest setHTTPBody:[querydataUsingEncoding:self.stringEncoding]];// 普通的POST請求參數,直接轉換成NSData設定到HTTP的body中。
}
return mutableRequest;
}
我們可以看到AFNetworking對于GET,POST請求參數的處理,一個是直接拼接在URL上面,一個是設定在HTTPBody裡面。
其中,HTTPMethodsEncodingParametersInURI的初始化如下:
self.HTTPMethodsEncodingParametersInURI = [NSSet setWithObjects:@"GET", @"HEAD", @"DELETE", nil]; // 支援GET,HEAD,DELETE
也就是GET,HEAD,DELETE支援的是參數直接拼接URL的方式。
AFJSONRequestSerialization中的實作:
- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
withParameters:(id)parameters
error:(NSError *__autoreleasing *)error
{
NSParameterAssert(request);
if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
return [super requestBySerializingRequest:request withParameters:parameters error:error];
}
NSMutableURLRequest *mutableRequest = [request mutableCopy];
[self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
if (![request valueForHTTPHeaderField:field]) {
[mutableRequest setValue:value forHTTPHeaderField:field];
}
}]; // 設定公共的請求頭
if (parameters) {
if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
[mutableRequest setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
}
[mutableRequest setHTTPBody:[NSJSONSerialization dataWithJSONObject:parameters options:self.writingOptions error:error]];
}
return mutableRequest;
}
OK,跟 AFURLRequestSerialization中的實作差不多,如果是HTTPMethodsEncodingParametersInURI請求方式是GET,HEAD,DELETE,則直接調用父類的解析方法。如果是POST等其他的,那麼做了一下設定請求頭Content-Type = “application/json”,并且将paramters參數Json 序列化成NSData,設定到HTTPBody裡面。
AFPropertyListRequestSerialization中的實作:
- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
withParameters:(id)parameters
error:(NSError *__autoreleasing *)error
{
NSParameterAssert(request);
if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
return [super requestBySerializingRequest:request withParameters:parameters error:error];
}
NSMutableURLRequest *mutableRequest = [request mutableCopy];
[self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
if (![request valueForHTTPHeaderField:field]) {
[mutableRequest setValue:value forHTTPHeaderField:field];
}
}];
if (parameters) {
if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
[mutableRequest setValue:@"application/x-plist" forHTTPHeaderField:@"Content-Type"];
}
[mutableRequest setHTTPBody:[NSPropertyListSerialization dataWithPropertyList:parameters format:self.format options:self.writeOptions error:error]];
}
return mutableRequest;
}
好吧,封裝思路跟 AFJSONRequestSerialization一樣,差別在于json序列化變成Plist的轉換。
二、AFURLResponseSerialization
功能:
負責對網絡請求傳回的資料進行解析。
類關系:
父類:AFHTTPResponseSerializer,二進制格式 子類:AFJSONResponseSerializer, JSON格式 AFXMLParseResponseSerializer, XML(隻能傳回XMLParser,還需要自己通過代了解析) AFXMLDocumentResponseSerializer, (Mac OS X) AFPropertyListResponseSerializer, Plist
AFImageResponseSerializer, Image AFCompoundResponseSerializer, 組合
封裝思路:
跟Request的封裝思路基本相同。隻不過這個是在資料請求到之後進行的處理。遵循的是AFURLResponseSerialization協定。實作方法:
- (id)responseObjectForResponse:(NSURLResponse *)response
data:(NSData *)data
error:(NSError *__autoreleasing *)error
此處的傳回值是id類型的,也就是資料解析完之後的資料。
順便提一下傳回值解析的調用函數是在AFURLSessionManager中的網絡請求成功的回調中:
- (void)URLSession:(__unused NSURLSession *)session
task:(NSURLSessionTask *)task
didCompleteWithError:(NSError *)error
{
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wgnu"
__strong AFURLSessionManager *manager = self.manager;
__block id responseObject = nil;
__block NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
userInfo[AFNetworkingTaskDidCompleteResponseSerializerKey] = manager.responseSerializer;
//Performance Improvement from #2672
NSData *data = nil;
if (self.mutableData) {
data = [self.mutableData copy];
//We no longer need the reference, so nil it out to gain back some memory.
self.mutableData = nil;
}
if (self.downloadFileURL) {
userInfo[AFNetworkingTaskDidCompleteAssetPathKey] = self.downloadFileURL;
} else if (data) {
userInfo[AFNetworkingTaskDidCompleteResponseDataKey] = data;
}
if (error) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = error;
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
if (self.completionHandler) {
self.completionHandler(task.response, responseObject, error);
}
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
} else {
dispatch_async(url_session_manager_processing_queue(), ^{
NSError *serializationError = nil;
responseObject = [manager.responseSerializer responseObjectForResponse:task.response data:data error:&serializationError]; // 此處進行資料的解析
if (self.downloadFileURL) {
responseObject = self.downloadFileURL;
}
if (responseObject) {
userInfo[AFNetworkingTaskDidCompleteSerializedResponseKey] = responseObject;
}
if (serializationError) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = serializationError;
}
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
if (self.completionHandler) {
self.completionHandler(task.response, responseObject, serializationError);
}
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
});
}
#pragma clang diagnostic pop
}
下面看一下各個類不同職能分别的實作:
父類AFHTTPResponseSerializer 中的實作:
- (id)responseObjectForResponse:(NSURLResponse *)response
data:(NSData *)data
error:(NSError *__autoreleasing *)error
{
[self validateResponse:(NSHTTPURLResponse *)response data:data error:error];
return data;
}
此處就一個方法,就是做了一個傳回的資料是否有效。但是資料是否有錯,都會傳回原始資料,沒有做任何的修改。 看一下傳回資料有效性的方法實作:
- (BOOL)validateResponse:(NSHTTPURLResponse *)response
data:(NSData *)data
error:(NSError * __autoreleasing *)error
{
BOOL responseIsValid = YES;
NSError *validationError = nil;
if (response && [response isKindOfClass:[NSHTTPURLResponse class]]) {
if (self.acceptableContentTypes && ![self.acceptableContentTypes containsObject:[response MIMEType]] &&
!([response MIMEType] == nil && [data length] == 0)) {
if ([data length] > 0 && [response URL]) {
NSMutableDictionary *mutableUserInfo = [@{
NSLocalizedDescriptionKey: [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: unacceptable content-type: %@", @"AFNetworking", nil), [response MIMEType]],
NSURLErrorFailingURLErrorKey:[response URL],
AFNetworkingOperationFailingURLResponseErrorKey: response,
} mutableCopy];
if (data) {
mutableUserInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] = data;
}
validationError = AFErrorWithUnderlyingError([NSError errorWithDomain:AFURLResponseSerializationErrorDomain code:NSURLErrorCannotDecodeContentData userInfo:mutableUserInfo], validationError);
}
responseIsValid = NO;
}
if (self.acceptableStatusCodes && ![self.acceptableStatusCodes containsIndex:(NSUInteger)response.statusCode] && [response URL]) {
NSMutableDictionary *mutableUserInfo = [@{
NSLocalizedDescriptionKey: [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: %@ (%ld)", @"AFNetworking", nil), [NSHTTPURLResponse localizedStringForStatusCode:response.statusCode], (long)response.statusCode],
NSURLErrorFailingURLErrorKey:[response URL],
AFNetworkingOperationFailingURLResponseErrorKey: response,
} mutableCopy];
if (data) {
mutableUserInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] = data;
}
validationError = AFErrorWithUnderlyingError([NSError errorWithDomain:AFURLResponseSerializationErrorDomain code:NSURLErrorBadServerResponse userInfo:mutableUserInfo], validationError);
responseIsValid = NO;
}
}
if (error && !responseIsValid) {
*error = validationError;
}
return responseIsValid;
}
這裡主要做了判斷是不是支援的傳回content-type類型,再就是狀态碼是不是200+,如果不滿足就不是有效的傳回資料。 看下初始化值:
self.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", nil];
self.acceptableStatusCodes = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(200, 100)];
子類AFJSONResponseSerializer中的實作:
- (id)responseObjectForResponse:(NSURLResponse *)response
data:(NSData *)data
error:(NSError *__autoreleasing *)error
{
if (![self validateResponse:(NSHTTPURLResponse *)response data:data error:error]) {
if (!error || AFErrorOrUnderlyingErrorHasCodeInDomain(*error, NSURLErrorCannotDecodeContentData, AFURLResponseSerializationErrorDomain)) {
return nil;
}
}
id responseObject = nil;
NSError *serializationError = nil;
// Workaround for behavior of Rails to return a single space for `head :ok` (a workaround for a bug in Safari), which is not interpreted as valid input by NSJSONSerialization.
// See https://github.com/rails/rails/issues/1742
BOOL isSpace = [data isEqualToData:[NSData dataWithBytes:" " length:1]];
if (data.length > 0 && !isSpace) {
responseObject = [NSJSONSerialization JSONObjectWithData:data options:self.readingOptions error:&serializationError];
} else {
return nil;
}
if (self.removesKeysWithNullValues && responseObject) {
responseObject = AFJSONObjectByRemovingKeysWithNullValues(responseObject, self.readingOptions);
}
if (error) {
*error = AFErrorWithUnderlyingError(serializationError, *error);
}
return responseObject;
}
此處看到在父類中對有效性的判斷結果并沒有做處理,而在Json轉換類中,如果傳回資料是無效的,直接就傳回nil。然後就是對傳回資料進行了Json轉換。并對結果進行了空值進行了排空。
其他的子類的封裝思路也都相似,不再一一贅述。注意的是不同的功能的子類對傳回值的類型支援是不同的。
如果文中有什麼錯誤,歡迎大家指正。