asihttp 源码分析一

一：发起一个同步请求

 

 ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
 [request startSynchronous];

 首先看一下ASIHTTPRequest 类

 

 @interface ASIHTTPRequest : NSOperation <NSCopying>

该类是NSOperation 的子类，所以该类的实例可以添加进 NSOperationQueue 队列中进行异步的请求。

 

发起synshronous请求的方法

 

 - (void)startSynchronous
 {
 #if DEBUG_REQUEST_STATUS || DEBUG_THROTTLING
     NSLog(@"Starting synchronous request %@",self);
 #endif
     [self setSynchronous:YES];
     [self setRunLoopMode:ASIHTTPRequestRunLoopMode];
     [self setInProgress:YES];

     if (![self isCancelled] && ![self complete]) {
         [self main];
         while (!complete) {
             [[NSRunLoop currentRunLoop] runMode:[self runLoopMode] beforeDate:[NSDate distantFuture]];
         }
     }

     [self setInProgress:NO];
 }

 

直接调用了[self main] 。

并且把runloopmode 设置为 ASIHTTPRequestRunLoopMode。

 

二：发起一个异步请求

 

   ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

   [request startAsynchronous];

 

startAsynchronous方法的实际内容为：

 

 - (void)startAsynchronous

     [sharedQueue addOperation:self];

 
request被加入到sharedQueue 队列中，在这里并没有看到该变量的初始化，那么它是在哪里被初始化的呢？？

 //在程序运行过程中，它会在你程序中每个类调用一次initialize。这个调用的时间发生在你的类接收到消息之前，但是在它的超类接收到initialize之后。

 + (void)initialize
 {
     if (self == [ASIHTTPRequest class]) {
         persistentConnectionsPool = [[NSMutableArray alloc] init];
         connectionsLock = [[NSRecursiveLock alloc] init];
         progressLock = [[NSRecursiveLock alloc] init];
         bandwidthThrottlingLock = [[NSLock alloc] init];
         sessionCookiesLock = [[NSRecursiveLock alloc] init];
         sessionCredentialsLock = [[NSRecursiveLock alloc] init];
         delegateAuthenticationLock = [[NSRecursiveLock alloc] init];
         bandwidthUsageTracker = [[NSMutableArray alloc] initWithCapacity:5];
         ASIRequestTimedOutError = [[NSError alloc] initWithDomain:NetworkRequestErrorDomain code:ASIRequestTimedOutErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"The request timed out",NSLocalizedDescriptionKey,nil]];
         ASIAuthenticationError = [[NSError alloc] initWithDomain:NetworkRequestErrorDomain code:ASIAuthenticationErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"Authentication needed",NSLocalizedDescriptionKey,nil]];
         ASIRequestCancelledError = [[NSError alloc] initWithDomain:NetworkRequestErrorDomain code:ASIRequestCancelledErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"The request was cancelled",NSLocalizedDescriptionKey,nil]];
         ASIUnableToCreateRequestError = [[NSError alloc] initWithDomain:NetworkRequestErrorDomain code:ASIUnableToCreateRequestErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"Unable to create request (bad url?)",NSLocalizedDescriptionKey,nil]];
         ASITooMuchRedirectionError = [[NSError alloc] initWithDomain:NetworkRequestErrorDomain code:ASITooMuchRedirectionErrorType userInfo:[NSDictionary dictionaryWithObjectsAndKeys:@"The request failed because it redirected too many times",NSLocalizedDescriptionKey,nil]];
         sharedQueue = [[NSOperationQueue alloc] init];
         [sharedQueue setMaxConcurrentOperationCount:4];

     }
 }

 

就是这个方法了。

并且sharedQueue的类型为NSOperationQueue 。并不是ASINetworkQueue，关于ASINetworkQueue类后面介绍

 

sharedQueue = [[NSOperationQueue alloc] init];
[sharedQueue setMaxConcurrentOperationCount:4];

 

 

三：关于http的一些信息

 

 

+ (id)requestWithURL:(NSURL *)newURL;

+ (id)requestWithURL:(NSURL *)newURL usingCache:(id <ASICacheDelegate>)cache;
+ (id)requestWithURL:(NSURL *)newURL usingCache:(id <ASICacheDelegate>)cache andCachePolicy:(ASICachePolicy)policy;

 

以上三种ASIHTTPRequest 的构建都是通过调用- (id)initWithURL:(NSURL *)newURL 方法。

 

 

 - (id)initWithURL:(NSURL *)newURL
 {
     self = [self init];
     [self setRequestMethod:@"GET"];
     [self setRunLoopMode:NSDefaultRunLoopMode];
     [self setShouldAttemptPersistentConnection:YES];
     [self setPersistentConnectionTimeoutSeconds:60.0];
     [self setShouldPresentCredentialsBeforeChallenge:YES];
     [self setShouldRedirect:YES];
     [self setShowAccurateProgress:YES];
     [self setShouldResetDownloadProgress:YES];
     [self setShouldResetUploadProgress:YES];
     [self setAllowCompressedResponse:YES];
     [self setShouldWaitToInflateCompressedResponses:YES];
     [self setDefaultResponseEncoding:NSISOLatin1StringEncoding];
     [self setShouldPresentProxyAuthenticationDialog:YES];

     [self setTimeOutSeconds:[ASIHTTPRequest defaultTimeOutSeconds]];
     [self setUseSessionPersistence:YES];
     [self setUseCookiePersistence:YES];
     [self setValidatesSecureCertificate:YES];
     [self setRequestCookies:[[[NSMutableArray alloc] init] autorelease]];
     [self setDidStartSelector:@selector(requestStarted:)];
     [self setDidReceiveResponseHeadersSelector:@selector(request:didReceiveResponseHeaders:)];
     [self setWillRedirectSelector:@selector(request:willRedirectToURL:)];
     [self setDidFinishSelector:@selector(requestFinished:)];
     [self setDidFailSelector:@selector(requestFailed:)];
     [self setDidReceiveDataSelector:@selector(request:didReceiveData:)];
     [self setURL:newURL];
     [self setCancelledLock:[[[NSRecursiveLock alloc] init] autorelease]];
     [self setDownloadCache:[[self class] defaultCache]];
     return self;
 }

 

该方法设置一个http请求相关的属性，已经一些lock 的初始化。

 

四：下面看看实际联网的方法 main（）

 

// Create the request
- (void)main{

 

}

改方法包含实际的请求逻辑，是整个的核心。

由于该方法过于庞大，在这里就不列出了，可以到ASIHTTPRequest.m文件中自行查找