iOS网络——AFNetworking AFHttpSessionManager源码解析

你要知道的NSURLSession都在这里

转载请注明出处 http://blog.csdn.net/u014205968/article/details/78481519

本系列文章主要讲解iOS中网络请求类NSURLSession的使用方法进行详解，同时也会以此为扩展，讲解SDWebImage中图片下载功能的源码分析，讲解AFNetworking相关源码分析。本系列文章主要分为以下几篇进行讲解，读者可按需查阅。

• iOS网络——NSURLSession详解及SDWebImage源码解析
• iOS网络——SDWebImage SDImageDownloader源码解析
• iOS网络——AFNetworking AFURLSessionManager源码解析
• iOS网络——AFNetworking AFHttpSessionManager源码解析

AFNetworking AFHTTPSessionManager源码解析

前一篇文章我们讲解了AFURLSessionManager的源码，最后还给了一个只使用AFURLSessionManager来创建NSURLSessionDataTask和NSURLSessionDownloadTask的栗子，但是发现创建下载任务真的很简单了，只需要传入要下载文件的NSURL对象，在传入几个回调块就能将文件下载到指定的目录中，并且可以监控下载进度，真的很方便，但NSURLSessionDataTask创建的任务默认是GET请求，如果需要其他如POST请求还需要修改request就显得有些麻烦了，今天要介绍的AFHTTPSessionManager就是继承自AFURLSessionManager，通过名称就知道这个类为HTTP访问提供了更加便捷的方法。

直接看头文件的声明源码:

//继承自AFURLSessionManager类@interface AFHTTPSessionManager : AFURLSessionManager <NSSecureCoding, NSCopying>//网络请求要访问的URL@property (readonly, nonatomic, strong, nullable) NSURL *baseURL;//请求序列化@property (nonatomic, strong) AFHTTPRequestSerializer <AFURLRequestSerialization> * requestSerializer;//响应序列化@property (nonatomic, strong) AFHTTPResponseSerializer <AFURLResponseSerialization> * responseSerializer;///-------------------------------/// @name Managing Security Policy///-------------------------------//安全策略@property (nonatomic, strong) AFSecurityPolicy *securityPolicy;///---------------------/// @name Initialization///---------------------//类方法返回一个AFHTTPSessionManager对象，不是单例，每次调用都重新创建+ (instancetype)manager;//构造函数- (instancetype)initWithBaseURL:(nullable NSURL *)url;//构造函数- (instancetype)initWithBaseURL:(nullable NSURL *)url           sessionConfiguration:(nullable NSURLSessionConfiguration *)configuration NS_DESIGNATED_INITIALIZER;///---------------------------/// @name Making HTTP Requests///---------------------------//获取一个GET请求- (nullable NSURLSessionDataTask *)GET:(NSString *)URLString                   parameters:(nullable id)parameters                      success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                      failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure DEPRECATED_ATTRIBUTE;//获取一个GET请求- (nullable NSURLSessionDataTask *)GET:(NSString *)URLString                            parameters:(nullable id)parameters                              progress:(nullable void (^)(NSProgress *downloadProgress))downloadProgress                               success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                               failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;//获取一个HEAD请求- (nullable NSURLSessionDataTask *)HEAD:(NSString *)URLString                    parameters:(nullable id)parameters                       success:(nullable void (^)(NSURLSessionDataTask *task))success                       failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;//获取一个POST请求- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString                    parameters:(nullable id)parameters                       success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                       failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure DEPRECATED_ATTRIBUTE;//获取一个POST请求- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString                             parameters:(nullable id)parameters                               progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgress                                success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                                failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;//获取一个POST请求- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString                    parameters:(nullable id)parameters     constructingBodyWithBlock:(nullable void (^)(id <AFMultipartFormData> formData))block                       success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                       failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure DEPRECATED_ATTRIBUTE;//获取一个POST请求- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString                             parameters:(nullable id)parameters              constructingBodyWithBlock:(nullable void (^)(id <AFMultipartFormData> formData))block                               progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgress                                success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                                failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;//获取一个PUT请求- (nullable NSURLSessionDataTask *)PUT:(NSString *)URLString                   parameters:(nullable id)parameters                      success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                      failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;//获取一个PATCH请求- (nullable NSURLSessionDataTask *)PATCH:(NSString *)URLString                     parameters:(nullable id)parameters                        success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                        failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;//获取一个DELETE请求- (nullable NSURLSessionDataTask *)DELETE:(NSString *)URLString                      parameters:(nullable id)parameters                         success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success                         failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;@end

AFHTTPSessionManager提供了一系列的构造方法以及HTTP访问的方法。

@interface AFHTTPSessionManager ()@property (readwrite, nonatomic, strong) NSURL *baseURL;@end@implementation AFHTTPSessionManager@dynamic responseSerializer;//类方法，返回一个新创建的AFHTTPSessionManager对象+ (instancetype)manager {    return [[[self class] alloc] initWithBaseURL:nil];}//构造函数- (instancetype)init {    return [self initWithBaseURL:nil];}//构造函数- (instancetype)initWithBaseURL:(NSURL *)url {    return [self initWithBaseURL:url sessionConfiguration:nil];}//构造函数- (instancetype)initWithSessionConfiguration:(NSURLSessionConfiguration *)configuration {    return [self initWithBaseURL:nil sessionConfiguration:configuration];}//构造函数- (instancetype)initWithBaseURL:(NSURL *)url           sessionConfiguration:(NSURLSessionConfiguration *)configuration{    //调用父类的构造函数    self = [super initWithSessionConfiguration:configuration];    if (!self) {        return nil;    }    // Ensure terminal slash for baseURL path, so that NSURL +URLWithString:relativeToURL: works as expected    if ([[url path] length] > 0 && ![[url absoluteString] hasSuffix:@"/"]) {        url = [url URLByAppendingPathComponent:@""];    }    self.baseURL = url;    //获取单例的请求序列化和响应序列化器    self.requestSerializer = [AFHTTPRequestSerializer serializer];    self.responseSerializer = [AFJSONResponseSerializer serializer];    return self;}#pragma mark -//setter- (void)setRequestSerializer:(AFHTTPRequestSerializer <AFURLRequestSerialization> *)requestSerializer {    NSParameterAssert(requestSerializer);    _requestSerializer = requestSerializer;}//setter- (void)setResponseSerializer:(AFHTTPResponseSerializer <AFURLResponseSerialization> *)responseSerializer {    NSParameterAssert(responseSerializer);    [super setResponseSerializer:responseSerializer];}@dynamic securityPolicy;//setter设置安全策略- (void)setSecurityPolicy:(AFSecurityPolicy *)securityPolicy {    if (securityPolicy.SSLPinningMode != AFSSLPinningModeNone && ![self.baseURL.scheme isEqualToString:@"https"]) {        NSString *pinningMode = @"Unknown Pinning Mode";        switch (securityPolicy.SSLPinningMode) {            case AFSSLPinningModeNone:        pinningMode = @"AFSSLPinningModeNone"; break;            case AFSSLPinningModeCertificate: pinningMode = @"AFSSLPinningModeCertificate"; break;            case AFSSLPinningModePublicKey:   pinningMode = @"AFSSLPinningModePublicKey"; break;        }        NSString *reason = [NSString stringWithFormat:@"A security policy configured with `%@` can only be applied on a manager with a secure base URL (i.e. https)", pinningMode];        @throw [NSException exceptionWithName:@"Invalid Security Policy" reason:reason userInfo:nil];    }    [super setSecurityPolicy:securityPolicy];}

上面的方法就是一系列构造函数，用于初始化父类对象以及序列化器，设置安全策略等，没有太多复杂的内容。

//GET请求，调用下面那个方法- (NSURLSessionDataTask *)GET:(NSString *)URLString                   parameters:(id)parameters                      success:(void (^)(NSURLSessionDataTask *task, id responseObject))success                      failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure{    return [self GET:URLString parameters:parameters progress:nil success:success failure:failure];}//GET请求- (NSURLSessionDataTask *)GET:(NSString *)URLString                   parameters:(id)parameters                     progress:(void (^)(NSProgress * _Nonnull))downloadProgress                      success:(void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success                      failure:(void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure{    //调用另一个方法构造GET请求    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"GET"                                                        URLString:URLString                                                       parameters:parameters                                                   uploadProgress:nil                                                 downloadProgress:downloadProgress                                                          success:success                                                          failure:failure];    /*    启动任务    使用AFHTTPSessionManager创建的任务默认都帮你启动了，所以不需要手动调用resume方法了    上一篇中讲解的AFURLSessionManager默认没有启动，所以获取任务后要手动启动    */    [dataTask resume];    return dataTask;}//获取HEAD请求- (NSURLSessionDataTask *)HEAD:(NSString *)URLString                    parameters:(id)parameters                       success:(void (^)(NSURLSessionDataTask *task))success                       failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure{    //同样调用下面的一个方法来获取    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"HEAD" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:^(NSURLSessionDataTask *task, __unused id responseObject) {        if (success) {            success(task);        }    } failure:failure];    //默认启动任务    [dataTask resume];    return dataTask;}//获取POST请求- (NSURLSessionDataTask *)POST:(NSString *)URLString                    parameters:(id)parameters                       success:(void (^)(NSURLSessionDataTask *task, id responseObject))success                       failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure{    //调用下面的方法获取    return [self POST:URLString parameters:parameters progress:nil success:success failure:failure];}//获取POST请求- (NSURLSessionDataTask *)POST:(NSString *)URLString                    parameters:(id)parameters                      progress:(void (^)(NSProgress * _Nonnull))uploadProgress                       success:(void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success                       failure:(void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure{    //同GET HEAD方法一样，调用一个方法获取任务    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"POST" URLString:URLString parameters:parameters uploadProgress:uploadProgress downloadProgress:nil success:success failure:failure];    //默认启动任务    [dataTask resume];    return dataTask;}//获取POST上传文件请求- (NSURLSessionDataTask *)POST:(NSString *)URLString                    parameters:(nullable id)parameters     constructingBodyWithBlock:(nullable void (^)(id<AFMultipartFormData> _Nonnull))block                       success:(nullable void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success                       failure:(nullable void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure{    //调用下面的方法来构造上传文件的POST请求    return [self POST:URLString parameters:parameters constructingBodyWithBlock:block progress:nil success:success failure:failure];}//上传文件POST请求- (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{    //构造一个request请求    NSError *serializationError = nil;    NSMutableURLRequest *request = [self.requestSerializer multipartFormRequestWithMethod:@"POST" URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters constructingBodyWithBlock:block error:&serializationError];    //如果在做序列化时出错在主线程调用failure回调块    if (serializationError) {        if (failure) {            dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{                failure(nil, serializationError);            });        }        return nil;    }    //调用父类的方法获取一个上传的任务    __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);            }        }    }];    //默认启动任务    [task resume];    return task;}//获取PUT请求- (NSURLSessionDataTask *)PUT:(NSString *)URLString                   parameters:(id)parameters                      success:(void (^)(NSURLSessionDataTask *task, id responseObject))success                      failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure{    //通过一个通用的方法来获取dataTask    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"PUT" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:success failure:failure];    //默认启动任务    [dataTask resume];    return dataTask;}//同上- (NSURLSessionDataTask *)PATCH:(NSString *)URLString                     parameters:(id)parameters                        success:(void (^)(NSURLSessionDataTask *task, id responseObject))success                        failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure{    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"PATCH" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:success failure:failure];    [dataTask resume];    return dataTask;}//同上- (NSURLSessionDataTask *)DELETE:(NSString *)URLString                      parameters:(id)parameters                         success:(void (^)(NSURLSessionDataTask *task, id responseObject))success                         failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure{    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"DELETE" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:success failure:failure];    [dataTask resume];    return dataTask;}//一个通用的方法来构造NSURLSessionDataTask- (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{    //通过请求序列化器构造一个request请求    //需要传入请求方法GET POST DELETE PUT这样的字符串 以及相关参数    NSError *serializationError = nil;    NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:method URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters error:&serializationError];    //如果序列化失败在主线程中执行failure回调块    if (serializationError) {        if (failure) {            dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{                failure(nil, serializationError);            });        }        return nil;    }    //序列化成功，调用父类的方法获取dataTask    __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);            }        }    }];    //返回dataTask    return dataTask;}

上面的代码也很简单，是在AFURLSessionManager之上做了一些处理，其中涉及的AFURLRequestSerialization和AFURLResponseSerialization由于不是本系列文章的关注点所以没有相关讲解，有需要的读者请自行查阅。

AFHTTPSessionManager继承自AFURLSessionManager并提供了更加便捷的网络请求接口，如果阅读了前一篇AFURLSessionManager可以发现它才是重点。AFHTTPSessionManager只是在它的基础上做了一些简单的封装，提供了更加便捷的接口。

通过AFURLSessionManager和AFHTTPSessionManager源码的阅读可以学习到AFNetworking在代码设计方面的优点，以及对NSURLSession的使用更清晰了。

备注

由于作者水平有限，难免出现纰漏，如有问题还请不吝赐教。