[无限互联]AFNetworking核心类AFURLConnectionOperation的详解

无限互联AFNetworking核心类AFURLConnectionOperation的详解我们先看看AFURLConnectionOperation 作为AFNetworking最核心的类到底有什么神奇之处！1.线程先来看看 NSURLConnection 发送请求时的线程情况，NSURLConnection 是被设计成异步发送的，调用了start方法后，NSURLConnection 会新建一些线程用底层的 CFSocket 去发送和接收请求，在发送和接收的一些事件发生后通知原来线程的Runloop去回调事件。NSURLConnection 的同步方法 sendSynchronousRequest 方法也是基于异步的，同样要在其他线程去处理请求的发送和接收，只是同步方法会手动block住线程，发送状态的通知也不是通过 RunLoop 进行。NSURLConnection发送有以下三种方式 在主线程调异步接口 在子线程调同步接口 在子线程调异步接口AFNetworking使用的是最后一种方式方法，AFNetworking内部相关线程大致的关系如下图所示NSURLConnection是一个系统控件，所以我们可以把NSURLConnection当做一个黑盒，只管它的 start 和 callback 就行了。如果使用 AFHttpRequestOperationManager 的接口发送请求，这些请求会统一在一个 NSOperationQueue 里去发，所以多了上面 NSOperationQueue 的一个线程。相关代码：objc view plaincopyprint?1. /-线程- 2. /* 3. 子线程调用异步接口，子线程需要有 Runloop 去接收异步回调事件，这里也可以每个请求都新建一条 4. 带有 Runloop 的线程去侦听回调，但这一点好处都没有，既然是异步回调，除了处理回调内容，其他 5. 时间线程都是空闲可利用的，所有请求共用一个响应的线程就够了。 6. */ 7. /获取当前的NSRunLoop，子线程使用共同的Runloop 8. + (void)networkRequestThreadEntryPoint:(id)_unused object 9. autoreleasepool 10. NSThread currentThread setName:AFNetworking; 11. NSRunLoop *runLoop = NSRunLoop currentRunLoop; 12. runLoop addPort:NSMachPort port forMode:NSDefaultRunLoopMode; 13. runLoop run; 14. 15. 16. /创建新的子线程 17. + (NSThread *)networkRequestThread 18. static NSThread *_networkRequestThread = nil; 19. static dispatch_once_t oncePredicate; 20. dispatch_once(&oncePredicate, 21. _networkRequestThread = NSThread alloc initWithTarget:self selector:selector(networkRequestThreadEntryPoint:) object:nil; 22. _networkRequestThread start; 23. ); 24. return _networkRequestThread; 25. 26. /初始化NSURLConnection对象 27. - (instancetype)initWithRequest:(NSURLRequest *)urlRequest 28. NSParameterAssert(urlRequest); 29. self = super init; 30. if (!self) 31. return nil; 32. 33. _state = AFOperationReadyState; 34. self.lock = NSRecursiveLock alloc init; 35. = kAFNetworkingLockName; 36. self.runLoopModes = NSSet setWithObject:NSRunLoopCommonModes; 37. self.request = urlRequest; 38. self.shouldUseCredentialStorage = YES; 39. self.securityPolicy = AFSecurityPolicy defaultPolicy; 40. return self; 41. /-线程-/* 子线程调用异步接口，子线程需要有 Runloop 去接收异步回调事件，这里也可以每个请求都新建一条 带有 Runloop 的线程去侦听回调，但这一点好处都没有，既然是异步回调，除了处理回调内容，其他 时间线程都是空闲可利用的，所有请求共用一个响应的线程就够了。 */获取当前的NSRunLoop，子线程使用共同的Runloop+ (void)networkRequestThreadEntryPoint:(id)_unused object autoreleasepool NSThread currentThread setName:AFNetworking; NSRunLoop *runLoop = NSRunLoop currentRunLoop; runLoop addPort:NSMachPort port forMode:NSDefaultRunLoopMode; runLoop run; /创建新的子线程+ (NSThread *)networkRequestThread static NSThread *_networkRequestThread = nil; static dispatch_once_t oncePredicate; dispatch_once(&oncePredicate, _networkRequestThread = NSThread alloc initWithTarget:self selector:selector(networkRequestThreadEntryPoint:) object:nil; _networkRequestThread start; ); return _networkRequestThread;/初始化NSURLConnection对象- (instancetype)initWithRequest:(NSURLRequest *)urlRequest NSParameterAssert(urlRequest); self = super init; if (!self) return nil; _state = AFOperationReadyState; self.lock = NSRecursiveLock alloc init; = kAFNetworkingLockName; self.runLoopModes = NSSet setWithObject:NSRunLoopCommonModes; self.request = urlRequest; self.shouldUseCredentialStorage = YES; self.securityPolicy = AFSecurityPolicy defaultPolicy; return self;objc view plaincopyprint?1. /-线程- 2. /线程开始 3. - (void)start 4. /加锁，保护线程 5. self.lock lock; 6. if (self isCancelled) /取消线程 7. self performSelector:selector(cancelConnection) onThread:self class networkRequestThread withObject:nil waitUntilDone:NO modes:self.runLoopModes allObjects; 8. else if (self isReady) /线程已准备 9. self.state = AFOperationExecutingState; /将线程调为执行状态 10.11. self performSelector:selector(operationDidStart) onThread:self class networkRequestThread withObject:nil waitUntilDone:NO modes:self.runLoopModes allObjects; 12. 13. /线程执行完毕，解锁 14. self.lock unlock; 15. 16. /线程已开始 17. - (void)operationDidStart 18. self.lock lock; 19. if (!self isCancelled) 20. /创建链接对象 21. self.connection = NSURLConnection alloc initWithRequest:self.request delegate:self startImmediately:NO; 22. /获取当前的NSRunLoop，用来接收异步回调事件 23. NSRunLoop *runLoop = NSRunLoop currentRunLoop; 24. for (NSString *runLoopMode in self.runLoopModes) 25. /执行线程 26. self.connection scheduleInRunLoop:runLoop forMode:runLoopMode; 27. self.outputStream scheduleInRunLoop:runLoop forMode:runLoopMode; 28. 29. /开始链接 30. self.connection start; 31. 32. self.lock unlock; 33. /回到主线程，发送线程开始通知 34. dispatch_async(dispatch_get_main_queue(), 35. NSNotificationCenter defaultCenter postNotificationName:AFNetworkingOperationDidStartNotification object:self; 36. ); 37. 38. /线程完成 39. - (void)finish 40. self.lock lock; 41. self.state = AFOperationFinishedState; 42. self.lock unlock; 43. /发送通知，链接完成 44. dispatch_async(dispatch_get_main_queue(), 45. NSNotificationCenter defaultCenter postNotificationName:AFNetworkingOperationDidFinishNotification object:self; 46. ); 47. 48. /线程取消 49. - (void)cancel 50. self.lock lock; 51. if (!self isFinished & !self isCancelled) 52. super cancel; 53.54. if (self isExecuting) 55. self performSelector:selector(cancelConnection) onThread:self class networkRequestThread withObject:nil waitUntilDone:NO modes:self.runLoopModes allObjects; 56. 57. 58. self.lock unlock; 59. 60. /取消链接 61. - (void)cancelConnection 62. NSDictionary *userInfo = nil; 63. if (self.request URL) 64. userInfo = NSDictionary dictionaryWithObject:self.request URL forKey:NSURLErrorFailingURLErrorKey; 65. 66. NSError *error = NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorCancelled userInfo:userInfo; 67. if (!self isFinished) /处于链接状态，取消链接 68. if (self.connection) 69. /取消链接 70. self.connection cancel; 71. self performSelector:selector(connection:didFailWithError:) withObject:self.connection withObject:error; 72. else /链接完成，则直接结束 73. / Accomodate race condition where self.connection has not yet been set before cancellation 74. self.error = error; 75. self finish; 76. 77. 78. /-线程-/线程开始- (void)start /加锁，保护线程 self.lock lock; if (self isCancelled) /取消线程 self performSelector:selector(cancelConnection) onThread:self class networkRequestThread withObject:nil waitUntilDone:NO modes:self.runLoopModes allObjects; else if (self isReady) /线程已准备 self.state = AFOperationExecutingState; /将线程调为执行状态 self performSelector:selector(operationDidStart) onThread:self class networkRequestThread withObject:nil waitUntilDone:NO modes:self.runLoopModes allObjects; /线程执行完毕，解锁 self.lock unlock;/线程已开始- (void)operationDidStart self.lock lock; if (!self isCancelled) /创建链接对象 self.connection = NSURLConnection alloc initWithRequest:self.request delegate:self startImmediately:NO; /获取当前的NSRunLoop，用来接收异步回调事件 NSRunLoop *runLoop = NSRunLoop currentRunLoop; for (NSString *runLoopMode in self.runLoopModes) /执行线程 self.connection scheduleInRunLoop:runLoop forMode:runLoopMode; self.outputStream scheduleInRunLoop:runLoop forMode:runLoopMode; /开始链接 self.connection start; self.lock unlock; /回到主线程，发送线程开始通知 dispatch_async(dispatch_get_main_queue(), NSNotificationCenter defaultCenter postNotificationName:AFNetworkingOperationDidStartNotification object:self; );/线程完成- (void)finish self.lock lock; self.state = AFOperationFinishedState; self.lock unlock; /发送通知，链接完成 dispatch_async(dispatch_get_main_queue(), NSNotificationCenter defaultCenter postNotificationName:AFNetworkingOperationDidFinishNotification object:self; );/线程取消- (void)cancel self.lock lock; if (!self isFinished & !self isCancelled) super cancel; if (self isExecuting) self performSelector:selector(cancelConnection) onThread:self class networkRequestThread withObject:nil waitUntilDone:NO modes:self.runLoopModes allObjects; self.lock unlock;/取消链接- (void)cancelConnection NSDictionary *userInfo = nil; if (self.request URL) userInfo = NSDictionary dictionaryWithObject:self.request URL forKey:NSURLErrorFailingURLErrorKey; NSError *error = NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorCancelled userInfo:userInfo; if (!self isFinished) /处于链接状态，取消链接 if (self.connection) /取消链接 self.connection cancel; self performSelector:selector(connection:didFailWithError:) withObject:self.connection withObject:error; else /链接完成，则直接结束 / Accomodate race condition where self.connection has not yet been set before cancellation self.error = error; self finish; 2.状态机继承 NSOperation 有个很麻烦的东西要处理，就是改变状态时需要发 KVO 通知，否则这个类加入 NSOperationQueue 不可用了。 NSOperationQueue 是用 KVO 方式侦听 NSOperation 状态的改变，以判断这个任务当前是否已完成，完成的任务需要在队列中除去并释放。AFURLConnectionOperation 对此做了个状态机，统一搞定状态切换以及发 KVO 通知的问题，内部要改变状态时，就只需要类似 self.state = AFOperationReadyState 的调用而不需要做其他了，状态改变的 KVO 通知在 setState 里发出。总的来说状态管理相关代码就三部分，一是限制一个状态可以切换到其他哪些状态，避免状态切换混乱，二是状态 Enum值 与 NSOperation 四个状态方法的对应，三是在 setState 时统一发 KVO 通知。相关代码如下：objc view plaincopyprint?1. /-状态机 2. /该方法的作用：状态 Enum值 与 NSOperation 四个状态方法的对应 3. static inline NSString * AFKeyPathFromOperationState(AFOperationState state) 4. switch (state) 5. case AFOperationReadyState: 6. return isReady; 7. case AFOperationExecutingState: 8. return isExecuting; 9. case AFOperationFinishedState: 10. return isFinished; 11. case AFOperationPausedState: 12. return isPaused; 13. default: 14. #pragma clang diagnostic push 15. #pragma clang diagnostic ignored -Wunreachable-code 16. return state; 17. #pragma clang diagnostic pop 18. 19. 20. 21. /NSOperation 状态的切换：限制一个状态可以切换到其他哪些状态，避免状态切换混乱 22. static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperationState toState, BOOL isCancelled) 23. switch (fromState) 24. case AFOperationReadyState: 25. switch (toState) 26. case AFOperationPausedState: 27. case AFOperationExecutingState: 28. return YES; 29. case AFOperationFinishedState: 30. return isCancelled; 31. default: 32. return NO; 33. 34. case AFOperationExecutingState: 35. switch (toState) 36. case AFOperationPausedState: 37. case AFOperationFinishedState: 38. return YES; 39. default: 40. return NO; 41. 42. case AFOperationFinishedState: 43. return NO; 44. case AFOperationPausedState: 45. return toState = AFOperationReadyState; 46. default: 47. #pragma clang diagnostic push 48. #pragma clang diagnostic ignored -Wunreachable-code 49. switch (toState) 50. case AFOperationPausedState: 51. case AFOperationReadyState: 52. case AFOperationExecutingState: 53. case AFOperationFinishedState: 54. return YES; 55. default: 56. return NO; 57. 58. 59. #pragma clang diagnostic pop 60. 61. /-状态机/该方法的作用：状态 Enum值 与 NSOperation 四个状态方法的对应static inline NSString * AFKeyPathFromOperationState(AFOperationState state) switch (state) case AFOperationReadyState: return isReady; case AFOperationExecutingState: return isExecuting; case AFOperationFinishedState: return isFinished; case AFOperationPausedState: return isPaused; default: #pragma clang diagnostic push#pragma clang diagnostic ignored -Wunreachable-code return state;#pragma clang diagnostic pop /NSOperation 状态的切换：限制一个状态可以切换到其他哪些状态，避免状态切换混乱static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperationState toState, BOOL isCancelled) switch (fromState) case AFOperationReadyState: switch (toState) case AFOperationPausedState: case AFOperationExecutingState: return YES; case AFOperationFinishedState: return isCancelled; default: return NO; case AFOperationExecutingState: switch (toState) case AFOperationPausedState: case AFOperationFinishedState: return YES; default: return NO; case AFOperationFinishedState: return NO; case AFOperationPausedState: return toState = AFOperationReadyState; default: #pragma clang diagnostic push#pragma clang diagnostic ignored -Wunreachable-code switch (toState) case AFOperationPausedState: case AFOperationReadyState: case AFOperationExecutingState: case AFOperationFinishedState: return YES; default: return NO; #pragma clang diagnostic pop objc view plaincopyprint?1. /-状态机 2. /NSOperationQueue 是用KVO方式侦听 NSOperation 状态的改变 3. /在该方法里统一发 KVO 通知给 NSOperationQueue，以判断这个任务当前是否已完成，完成的任务需要在队列中除去并释放。 4. - (void)setState:(AFOperationState)state 5. if (!AFStateTransitionIsValid(self.state, state, self isCancelled) 6. return; 7. 8. self.lock lock; 9. NSString *oldStateKey = AFKeyPathFromOperationState(self.state); 10. NSString *newStateKey = AFKeyPathFromOperationState(state); 11. self willChangeValueForKey:newStateKey; 12. self willChangeValueForKey:oldStateKey; 13. _state = state; 14. self didChangeValueForKey:oldStateKey; 15. self didChangeValueForKey:newStateKey; 16. self.lock unlock; 17. /-状态机/NSOperationQueue 是用KVO方式侦听 NSOperation 状态的改变/在该方法里统一发 KVO 通知给 NSOperationQueue，以判断这个任务当前是否已完成，完成的任务需要在队列中除去并释放。- (void)setState:(AFOperationState)state if (!AFStateTransitionIsValid(self.state, state, self isCancelled) return; self.lock lock; NSString *oldStateKey = AFKeyPathFromOperationState(self.state); NSString *newStateKey = AFKeyPathFromOperationState(state); self willChangeValueForKey:newStateKey; self willChangeValueForKey:oldStateKey; _state = state; self didChangeValueForKey:oldStateKey; self didChangeValueForKey:newStateKey; self.lock unlock;objc view plaincopyprint?1. 还有其他相关代码：-setState:, -isPaused:, -isReady:, -isExecuting:, -isFinished:. 还有其他相关代码：-setState:, -isPaused:, -isReady:, -isExecuting:, -isFinished:.3.NSURLConnectionDelegate处理 NSURLConnection Delegate 的内容不多，代码也是按请求回调的顺序排列下去，十分易读，主要流程就是接收到响应的时候打开 outputStream，接着有数据过来就往 outputStream 写，在上传/接收数据过程中会回调上层传进来的相应的callback，在请求完成回调到 connectionDidFinishLoading 时，关闭 outputStream，用 outputStream 组装 responseData 作为接收到的数据，把 NSOperation 状态设为 finished，表示任务完成，NSOperation 会自动调用 completeBlock，再回调到上层。相关代码如下：objc view plaincopyprint?1. /使用NSURLConnection时，用该方法检查证书的有效性 2. - (void)connection:(NSURLConnection *)connection 3. willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge /使用NSURLConnection时，用该方法检查证书的有效性- (void)connection:(NSURLConnection *)connectionwillSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challengeobjc view plaincopyprint?1. /* 2. connection: willSendRequest: redirectResponse: 3. 这个方法在请求将要被发送出去之前会调用 4. 返回值是一个NSURLRequest,就是那个真正将要被发送的请求 5. 第二个参数request就是被重定向处理过后的请求 6. 第三个参数redirectResponse是触发重定向请求的响应包.默认是支持跳转的。 7. */ 8. - (NSURLRequest *)connection:(NSURLConnection *)connection 9. willSendRequest:(NSURLRequest *)request 10. redirectResponse:(NSURLResponse *)redirectResponse 11. 12. if (self.redirectResponse) 13. return self.redirectResponse(connection, request, redirectResponse); 14. else 15. return request; 16. 17. 18. /上传数据 19. - (void)connection:(NSURLConnection _unused *)connection 20. didSendBodyData:(NSInteger)bytesWritten 21. totalBytesWritten:(NSInteger)totalBytesWritten 22. totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite 23. 24. /上传数据过程中回调上层传进来的相应的callback 25. if (self.uploadProgress) 26. dispatch_async(dispatch_get_main_queue(), 27. self.uploadProgress(NSUInteger)bytesWritten, totalBytesWritten, totalBytesExpectedToWrite); 28. ); 29. 30. 31. /代理对象接收到响应的时候打开 outputStream 32. - (void)connection:(NSURLConnection _unused *)connection 33. didReceiveRe