NSURLCache – 参数不工作的GET请求的磁盘caching

我试图使用NSURLCachecaching一些HTTP请求到磁盘。 在使用AFNetworking进行一些testing之后，我使用NSURLRequest创build了一个简单的示例。

我像这样初始化AppDelegate上的caching，将内存大小设置为0，强制它始终移到磁盘：

NSUInteger sz = 1024*1024*20; NSURLCache *cache = [[NSURLCache alloc] initWithMemoryCapacity:0 diskCapacity:sz diskPath:nil]; [NSURLCache setSharedURLCache:cache]; 

我使用下面的代码来存储响应：

NSURLCache * urlCache = [NSURLCache sharedURLCache];

 NSString *urlString = @"http://localhost:8000/cities/api/cities/?lang=en"; NSHTTPURLResponse *response = nil; NSError *error = nil; NSURL *finalUrl = [NSURL URLWithString:urlString]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:finalUrl]; request.cachePolicy = NSURLRequestReturnCacheDataElseLoad; NSData *data = nil; data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; NSCachedURLResponse *cachedResponse = [[NSCachedURLResponse alloc] initWithResponse:response data:data userInfo:nil storagePolicy:NSURLCacheStorageAllowed]; [urlCache storeCachedResponse:cachedResponse forRequest:request]; 

我的请求有HTTP头caching控制像：

响应['cache-control'] ='max-age = 36000，public'

我看到响应被caching在Cache.db文件中。

之后，在下一次执行中，甚至在同一次执行中，我使用以下代码尝试从caching中获取响应：

 NSCachedURLResponse *cachedResponse = [urlCache cachedResponseForRequest:request]; response = cachedResponse.response; data = cachedResponse.data; 

问题是， 当请求具有GET参数时 ，cachedResponse始终为空。 如果请求是“ http：// localhost：8000 / cities / api / cities / ”，则结果稍后存储和恢复。 但是，当它具有GET参数时，阻止[NSURLCache cachedResponseForRequest：request]方法find请求。

给了这个，我分类NSURLCache和实现这样的方法：

 - (id)initWithMemoryCapacity:(NSUInteger)memoryCapacity diskCapacity:(NSUInteger)diskCapacity diskPath:(NSString *)path { self = [super initWithMemoryCapacity:memoryCapacity diskCapacity:diskCapacity diskPath:path]; if (self) { NSArray *docPaths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES); NSString *dir = (NSString*)[docPaths objectAtIndex:0]; dir = [dir stringByAppendingString:@"/uk.co.airsource.TestURLCache/nsurlcache"]; NSString *path = [dir stringByAppendingFormat:@"/Cache.db"]; self.db = [[FMDatabase alloc] initWithPath:path]; [self.db open]; int o = 4; } return self; 

}

 - (NSCachedURLResponse *) cachedResponseForRequest:(NSURLRequest *)request { NSCachedURLResponse *cachedURLResponse = [super cachedResponseForRequest:request]; if (cachedURLResponse == nil && [request.HTTPMethod isEqualToString:@"GET"]) { //[db executeQuery:@"select * from test where a = ?", @"hi'", nil]; NSLog(@"%@", request.URL.absoluteString); FMResultSet *cfurl_cache_response = [self.db executeQuery:@"select * from cfurl_cache_response where request_key = ? limit 1", request.URL.absoluteString, nil]; if ([cfurl_cache_response next]) { id entry_ID = [cfurl_cache_response objectForColumnName:@"entry_ID"]; [cfurl_cache_response close]; if (entry_ID != [NSNull null]) { FMResultSet *cfurl_cache_blob_data = [self.db executeQuery:@"select * from cfurl_cache_blob_data where entry_ID = ? limit 1", entry_ID, nil]; if ([cfurl_cache_blob_data next]) { id response_object = [cfurl_cache_blob_data objectForColumnName:@"response_object"]; [cfurl_cache_blob_data close]; FMResultSet *cfurl_receiver_data = [self.db executeQuery:@"select * from cfurl_cache_receiver_data where entry_ID = ? limit 1", entry_ID, nil]; if ([cfurl_receiver_data next]) { id receiver_data = [cfurl_receiver_data objectForColumnName:@"receiver_data"]; [cfurl_receiver_data close]; if (response_object != [NSNull null] && receiver_data != [NSNull null] && response_object && receiver_data) { NSURLResponse *urlResponse = [[NSURLResponse alloc] initWithURL:request.URL MIMEType:[[request allHTTPHeaderFields] objectForKey:@"Accept"] expectedContentLength:[(NSData *)response_object length] textEncodingName:nil]; cachedURLResponse = [[NSCachedURLResponse alloc] initWithResponse:urlResponse data:receiver_data userInfo:nil storagePolicy:NSURLCacheStorageAllowed]; } } } } } } return cachedURLResponse; 

}

在这种情况下，带有参数的GET请求下，它会跟随每一行，直到获得之前被caching的NSURLResponse。

任何想法，为什么请求有GET参数时，它不正常工作？

Answer 1

问题似乎是没有指定内存容量，如果您指定的内存容量如下，

在这里，我指定的内存容量是1 MB的大小

 [[NSURLCache alloc] initWithMemoryCapacity:1*1024*1024 diskCapacity:sz diskPath:nil]; 

它会起作用，看起来好像内存容量是不pipe用的，容量有多小，但不能空着。 那么你将能够提取存储的caching如下，

 NSCachedURLResponse *cachedResponse = [[NSURLCache sharedURLCache] cachedResponseForRequest:request]; response = cachedResponse.response; data = cachedResponse.data; 

Answer 2

最后，我重写了NSURLCache，以便能够实现我正在寻找的内容：

1. GET请求（带参数）被caching到磁盘
2. 当“Cache-Control max-age”值表明它没有过期，并在到期后再次进入服务器，存储新的响应并开始到期时间
3. 如果处于脱机状态，则始终从caching中返回响应（如果存在）

NTURLCache – 覆盖NSURLCache

我认真地认为这是一个在iOS 8.1中无法正常工作的问题