内容简介：AFNetWorking是使用AFNetWorking主要分为5个部分。整个AFNetWorking组织结构如下：
AFNetworking源码学习
简介
AFNetWorking是使用 Objective-c 开发iOS程序主流的网络请求开源库。
AFNetworking组织结构
AFNetWorking主要分为5个部分。 NSURLSession 、 Reachability 、 security 、 Serialization 、 UIKit 。其中NSURLSession是整个网络请求开源库的 灵魂 ，对外提供了丰富的网络请求接口。包括 GET 、 POST 、 HEAD 、 PUT 、 DELETE ，与及文件上传的接口。
整个AFNetWorking组织结构如下：
源码解读
1.NSURLSession
NSURLSession包括 AFURLSessionManager 和 AFHTTPSessionManager ，AFHTTPSessionManager继承了AFURLSessionManager，对外提供了网络请求的接口。我们最常使用的 GET 、 POST 接口，底层都调用了
- (NSURLSessionDataTask *)dataTaskWithHTTPMethod:(NSString *)method
URLString:(NSString *)URLString
parameters:(id)parameters
uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgress
downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgress
success:(void (^)(NSURLSessionDataTask *, id))success
failure:(void (^)(NSURLSessionDataTask *, NSError *))failure
整个方法的实现如下：
- (NSURLSessionDataTask *)dataTaskWithHTTPMethod:(NSString *)method
URLString:(NSString *)URLString
parameters:(id)parameters
uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgress
downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgress
success:(void (^)(NSURLSessionDataTask *, id))success
failure:(void (^)(NSURLSessionDataTask *, NSError *))failure
{
NSError *serializationError = nil;
NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:method URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters error:&serializationError];
if (serializationError) {
if (failure) {
dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{
failure(nil, serializationError);
});
}
return nil;
}
__block NSURLSessionDataTask *dataTask = nil;
dataTask = [self dataTaskWithRequest:request
uploadProgress:uploadProgress
downloadProgress:downloadProgress
completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {
if (error) {
if (failure) {
failure(dataTask, error);
}
} else {
if (success) {
success(dataTask, responseObject);
}
}
}];
return dataTask;
}
文件上传的接口例外，文件上传涉及到数据分片的问题，使用的是一个叫`- (NSURLSessionDataTask )POST:(NSString )URLString
parameters:(id)parameters
constructingBodyWithBlock:(void (^)(id <AFMultipartFormData> formData))block
progress:(nullable void (^)(NSProgress * _Nonnull))uploadProgress
success:(void (^)(NSURLSessionDataTask *task, id responseObject))success
failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure`接口，这个接口的全部实现如下：
- (NSURLSessionDataTask *)POST:(NSString *)URLString
parameters:(id)parameters
constructingBodyWithBlock:(void (^)(id <AFMultipartFormData> formData))block
progress:(nullable void (^)(NSProgress * _Nonnull))uploadProgress
success:(void (^)(NSURLSessionDataTask *task, id responseObject))success
failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure
{
NSError *serializationError = nil;
NSMutableURLRequest *request = [self.requestSerializer multipartFormRequestWithMethod:@"POST" URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters constructingBodyWithBlock:block error:&serializationError];
if (serializationError) {
if (failure) {
dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{
failure(nil, serializationError);
});
}
return nil;
}
__block NSURLSessionDataTask *task = [self uploadTaskWithStreamedRequest:request progress:uploadProgress completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {
if (error) {
if (failure) {
failure(task, error);
}
} else {
if (success) {
success(task, responseObject);
}
}
}];
[task resume];
return task;
}
AFURLSessionManager
AFURLSessionManager是整个网络请求框架的核心。
创建了 url_session_manager_creation_queue 、 url_session_manager_processing_queue 、
url_session_manager_completion_group，这三个都是单例的形式。
AFURLSessionManager是以 串行队列 的方式进行session管理的。安全策略使用的是默认策略。`- (NSURLSessionDataTask )dataTaskWithRequest:(NSURLRequest )request
uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgressBlock
downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler`以安全的方式，创建了一个dataTask，最后加入到mutableTask的**NSMutableDictionary**中。
AFURLSessionManager是AFHTTPSessionManager的基础，对AFHTTPSessionManager提供了 downloadTask 、 uploadTask 、 dataTask 等等的封装。
2.AFNetworkReachabilityManager
AFNetworkReachabilityManager监测网络状态。方法如下：
static AFNetworkReachabilityStatus AFNetworkReachabilityStatusForFlags(SCNetworkReachabilityFlags flags) {
BOOL isReachable = ((flags & kSCNetworkReachabilityFlagsReachable) != 0);
BOOL needsConnection = ((flags & kSCNetworkReachabilityFlagsConnectionRequired) != 0);
BOOL canConnectionAutomatically = (((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) || ((flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0));
BOOL canConnectWithoutUserInteraction = (canConnectionAutomatically && (flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0);
BOOL isNetworkReachable = (isReachable && (!needsConnection || canConnectWithoutUserInteraction));
AFNetworkReachabilityStatus status = AFNetworkReachabilityStatusUnknown;
if (isNetworkReachable == NO) {
status = AFNetworkReachabilityStatusNotReachable;
}
#if TARGET_OS_IPHONE
else if ((flags & kSCNetworkReachabilityFlagsIsWWAN) != 0) {
status = AFNetworkReachabilityStatusReachableViaWWAN;
}
#endif
else {
status = AFNetworkReachabilityStatusReachableViaWiFi;
}
return status;
}
根据传入的 SCNetworkReachabilityFlags 标志进行判断，返回对应的网络状态。
3.AFSecurityPolicy
AFSecurityPolicy，网络请求的安全策略。该类提供了三种安全策略：
typedef NS_ENUM(NSUInteger, AFSSLPinningMode) {
AFSSLPinningModeNone,
AFSSLPinningModePublicKey,
AFSSLPinningModeCertificate,
};
默认的安全策略是 AFSSLPinningModeNone ，我们可以根据需要设置对应的安全策略。
开发中实际的设置栗子如下：
- (void)setupSecurityPolicy {
AFSecurityPolicy *securityPolicy = [AFSecurityPolicy policyWithPinningMode:AFSSLPinningModePublicKey];
[securityPolicy setAllowInvalidCertificates:YES];
[securityPolicy setValidatesDomainName:YES];
self.sessionManager.securityPolicy = securityPolicy;
}
我们当时使用的是 SSL 对传输的数据进行加密，来达到数据的安全传输。
4.AFURLRequestSerialization
里面是对客户端发起的请求的序列化。
- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
withParameters:(id)parameters
error:(NSError *__autoreleasing *)error
{
NSParameterAssert(request);
NSMutableURLRequest *mutableRequest = [request mutableCopy];
[self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
if (![request valueForHTTPHeaderField:field]) {
[mutableRequest setValue:value forHTTPHeaderField:field];
}
}];
NSString *query = nil;
if (parameters) {
if (self.queryStringSerialization) {
NSError *serializationError;
query = self.queryStringSerialization(request, parameters, &serializationError);
if (serializationError) {
if (error) {
*error = serializationError;
}
return nil;
}
} else {
switch (self.queryStringSerializationStyle) {
case AFHTTPRequestQueryStringDefaultStyle:
query = AFQueryStringFromParameters(parameters);
break;
}
}
}
if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
if (query && query.length > 0) {
mutableRequest.URL = [NSURL URLWithString:[[mutableRequest.URL absoluteString] stringByAppendingFormat:mutableRequest.URL.query ? @"&%@" : @"?%@", query]];
}
} else {
// #2864: an empty string is a valid x-www-form-urlencoded payload
if (!query) {
query = @"";
}
if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
[mutableRequest setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
}
[mutableRequest setHTTPBody:[query dataUsingEncoding:self.stringEncoding]];
}
return mutableRequest;
}
对请求参数进行拼接，序列化，设置request的 Content-Type ，然后把序列化后的参数设置到 HTTPBody 中。
还有对应的序列化类 AFJSONRequestSerializer & AFPropertyListRequestSerializer ，可以把请求参数根据 Content-Type 序列化成 application/json 或者 application/x-plist 格式。
5.AFURLResponseSerialization
response序列化就是把响应数据使用数据解析器解析成对应的格式。 AFURLResponseSerialization 提供的解析器有：
- AFJSONResponseSerializer -> application/json / text/json / text/javascript
- AFXMLParserResponseSerializer -> application/xml / text/xml
- AFPropertyListResponseSerializer -> application/x-plist
- AFImageResponseSerializer -> image/jpeg / image/gif / image/png ，这三种是常用的，还有其他好几种，可以到源码中查看。
- AFCompoundResponseSerializer 合成解析器，是上面几种的集合。
以上所述就是小编给大家介绍的《AFNetworking源码学习》，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对 码农网 的支持！
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