ASIHttpRequest是一个非常好的库，只是直接使用稍嫌麻烦，以下就尝试来封装一下吧。
思路：每次请求时，须要创建一个ASIHttpRequest对象，设置它的属性（url，delegate。postValue，requestMethod等）之后就可以開始异步请求。所以我们能够创建一个类。对外提供一个请求方法，结构例如以下：
@interface RequestService : NSObject+ (void)requestWithUrlString:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id)delegate;@end
使用例如以下：
[RequestService requestWithUrlString:urlString params:params httpMethod:httpMethod delegate:delegate];看起来非常easy嘛，这样即可了吗？
考虑一个问题，此时传入的delegate是请发起请求的对象。假设我们想要对请求返回做统一的处理，就无法做到了。为了实现这一目的，能够将ASIHttpRequest的delegate设置成RequestService实例对象，请求返回昨晚处理后再将处理结果通知给发起请求的对象。
那么RequestService请求的方法就须要改成实例方法。
改动后代码例如以下：
@protocol RequestServiceDelegate注意除了将类方法改动成实例方法之外，我们去掉了方法传參ASIHttpRequestDelegate，同一时候给它加了自己的delegate属性。用于在请求返回处理完毕后通知发起请求的对象。- (void)requestWillBegin;- (void)requestDidSucceedWithData:(id)data;- (void)requestDidFailWithError:(NSError *)error;@end@interface RequestService : NSObject@property (nonatomic,assign)id delegate;- (void)requestWithUrlString:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod;@end
使用例如以下：
RequestService *request = [[RequestService alloc] init]; request.delegate = self; [request requestWithUrlString:urlString params:params httpMethod:httpMethod];在这里须要特别注意创建的request对象的生命周期，由于ASIHttpRequest运行的是异步请求，当请求完毕，通知request对象时。假设request对象已经销毁，那么代码就会报错。因此使用时，须要发起请求的对象持有此request。并在请求完毕后释放它。
让每一个对象管理请求，听起来就非常麻烦，又违背了想要统一管理的初衷，那么应该怎么办呢？
让我们来使用单例吧！
创建一个单例对象HttpClient。它有一个属性requestItems。
每次发起请求时，将请求的Item存入该属性。
请求结束后移除Item。
对外，它要提供一个request方法，并须要一个属性保存发起请求的对象。
HttpClient的结构例如以下：
@protocol HttpClientDelegate使用例如以下：- (void)requestDidFinishWithData:(NSDictionary *)data urlString:(NSString *)urlString nTag:(NSInteger)nTag sKey:(NSString *)sKey;- (void)requestDidFailWithError:(NSError *)error urlString:(NSString *)urlString nTag:(NSInteger)nTag sKey:(NSString *)sKey;@end@interface HttpClient : NSObject@property (nonatomic,strong)NSMutableDictionary *items;+ (HttpClient *)sharedClient;- (void)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate;@end
[[HttpClient sharedClient] requestWithUrl:kProductListURL params:params httpMethod:@"GET" delegate:self];HttpClient内部怎样实现对每次request的管理呢？首先在请求时，创建一个requestItem，调用requestItem的请求方法，然后将其增加requestItems。当requestItem接收到返回时，通知HttpClient，最后由HttpClient通知发起请求的对象，并移除该requestItem。
HttpClient的request方法例如以下：
- (void)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id用于接收RequestItem的通知方法例如以下：)delegate{ HttpRequestItem *item = [[HttpRequestItem alloc] init]; item.delegate = delegate; [item requestWithUrlString:urlString params:params httpMethod:httpMethod]; NSUInteger hashValue = [item hash]; [self.items addObject:item];}
- (void)didFinishWithItem:(HttpRequestItem *)item error:(NSError *)error{ if (error == nil) { // 请求成功 if (item.delegate && [item.delegate respondsToSelector:@selector(requestDidFinishWithData:urlString:nTag:sKey:)]) { NSDictionary *data = [NSJSONSerialization JSONObjectWithData:item.httpReq.responseData options:NSJSONReadingMutableContainers error:nil]; [item.delegate requestDidFinishWithData:data urlString:item.urlString nTag:item.nTag sKey:item.sKey]; } } else { // 请求出错 if (item.delegate && [item.delegate respondsToSelector:@selector(requestDidFailWithError:urlString:nTag:sKey:)]) { [item.delegate requestDidFailWithError:error urlString:item.urlString nTag:item.nTag sKey:item.sKey]; } } [self removeItem:item];}HttpRequestItem也就是我们之前的RequestService，它接收ASIHttpRequest的返回的方法例如以下： #pragma mark - ASIHTTPRequest delegate- (void)requestFinished:(ASIHTTPRequest *)request{ NSError *error = nil; // doSomething with response here.... if ([[HttpClient sharedClient] respondsToSelector:@selector(didFinishWithItem:error:)]) { [[HttpClient sharedClient] performSelector:@selector(didFinishWithItem:error:) withObject:self withObject:error]; }}- (void)requestFailed:(ASIHTTPRequest *)request{ if ([[HttpClient sharedClient] respondsToSelector:@selector(didFinishWithItem:error:)]) { [[HttpClient sharedClient] performSelector:@selector(didFinishWithItem:error:) withObject:self withObject:request.error]; }}以上，主要的雏形已经出来了~还有哪些能够改进的地方呢？ 考虑两个问题：
1.同一个对象，可能会发起多次请求，怎样差别这些请求的返回？
2.假设想主动取消某个正在进行的请求，应该怎么办？
对于问题1，可在请求时传入參数，如tag、key等，由RequestItem保存这些參数，请求完毕后依据这些參数来区分不同的请求。
对于问题2。相应方法是记录每一个RequestItem的HashValue，并对外提供依据HashValue取消相应请求的方法。
完整的代码例如以下：
HttpClient.h
#importHttpClient.m@protocol HttpClientDelegate - (void)requestDidFinishWithData:(NSDictionary *)data urlString:(NSString *)urlString nTag:(NSInteger)nTag sKey:(NSString *)sKey;- (void)requestDidFailWithError:(NSError *)error urlString:(NSString *)urlString nTag:(NSInteger)nTag sKey:(NSString *)sKey;@end@interface HttpClient : NSObject@property (nonatomic,strong)NSMutableDictionary *items;+ (HttpClient *)sharedClient;- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate;- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate nTag:(NSInteger)nTag;- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate sKey:(NSString *)sKey;- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate nTag:(NSInteger)nTag sKey:(NSString *)sKey;// 取消请求- (BOOL)cancelRequestWithHashValue:(NSUInteger)hashValue;@end
#import "HttpClient.h"#import "HttpRequestItem.h"@implementation HttpClient+ (HttpClient *)sharedClient { static HttpClient *_sharedClient = nil; static dispatch_once_t oncePredicate; dispatch_once(&oncePredicate, ^{ _sharedClient = [[self alloc] init]; _sharedClient.items = [NSMutableDictionary dictionary]; }); return _sharedClient;}- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate{ return [self requestWithUrl:urlString params:params httpMethod:httpMethod delegate:delegate nTag:0 sKey:nil];}- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate nTag:(NSInteger)nTag{ return [self requestWithUrl:urlString params:params httpMethod:httpMethod delegate:delegate nTag:nTag sKey:nil];}- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate sKey:(NSString *)sKey{ return [self requestWithUrl:urlString params:params httpMethod:httpMethod delegate:delegate nTag:0 sKey:sKey];}- (NSUInteger)requestWithUrl:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod delegate:(id )delegate nTag:(NSInteger)nTag sKey:(NSString *)sKey{ HttpRequestItem *item = [[HttpRequestItem alloc] init]; item.delegate = delegate; item.nTag = nTag; item.sKey = sKey; [item requestWithUrlString:urlString params:params httpMethod:httpMethod]; NSUInteger hashValue = [item hash]; [self.items setObject:item forKey:@(hashValue)]; return hashValue;}- (BOOL)cancelRequestWithHashValue:(NSUInteger)hashValue{ HttpRequestItem *item = [_items objectForKey:@(hashValue)]; if (item) { [item.httpReq clearDelegatesAndCancel]; [_items removeObjectForKey:@(hashValue)]; } return YES;}#pragma mark - actions- (void)removeItem:(HttpRequestItem *)item{ NSUInteger hashValue = [item hash]; id object = [_items objectForKey:@(hashValue)]; if (object != nil) { [[(HttpRequestItem *)object httpReq] clearDelegatesAndCancel]; [_items removeObjectForKey:@(hashValue)]; }}#pragma mark - HttpRequestItem delegate// 请求结束- (void)didFinishWithItem:(HttpRequestItem *)item error:(NSError *)error{ if (error == nil) { // 请求成功 if (item.delegate && [item.delegate respondsToSelector:@selector(requestDidFinishWithData:urlString:nTag:sKey:)]) { NSDictionary *data = [NSJSONSerialization JSONObjectWithData:item.httpReq.responseData options:NSJSONReadingMutableContainers error:nil]; [item.delegate requestDidFinishWithData:data urlString:item.urlString nTag:item.nTag sKey:item.sKey]; } } else { // 请求出错 if (item.delegate && [item.delegate respondsToSelector:@selector(requestDidFailWithError:urlString:nTag:sKey:)]) { [item.delegate requestDidFailWithError:error urlString:item.urlString nTag:item.nTag sKey:item.sKey]; } } [self removeItem:item];}@end HttpRequestItem.h #import#import "ASIFormDataRequest.h"#import "RequestConstants.h"#import "HttpClient.h"@interface HttpRequestItem : NSObject@property (nonatomic,strong)ASIHTTPRequest *httpReq;@property (nonatomic,copy)NSString *urlString;@property (nonatomic,assign)NSInteger nTag;@property (nonatomic,copy)NSString *sKey;@property (nonatomic,assign)id delegate;- (void)requestWithUrlString:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod;@end
HttpRequestItem.m
#import "HttpRequestItem.h"NSString * const kHttpBaseURLString = @"http://192.168.33.6:8080/";@implementation HttpRequestItem- (void)requestWithUrlString:(NSString *)urlString params:(NSDictionary *)params httpMethod:(NSString *)httpMethod{ ASIFormDataRequest *request; NSURL *url; urlString = [kHttpBaseURLString stringByAppendingString:urlString]; if ([[httpMethod lowercaseString] isEqualToString:@"post"]) { // post方式訪问接口 url = [NSURL URLWithString:urlString]; request = [ASIFormDataRequest requestWithURL:url]; [request setRequestMethod:@"POST"]; for (NSString *key in params) { id value = [params objectForKey:key]; if (![value isKindOfClass:[NSData class]]) { [request addPostValue:value forKey:key]; } else { [request addData:value forKey:key]; } } } else { // get方式訪问接口 urlString = [urlString stringByAppendingString:@"?format=json"]; for (NSString *key in params) { urlString = [urlString stringByAppendingFormat:@"&%@=%@", key, [params objectForKey:key]]; } NSLog(@"-----------url:%@-----------",urlString); NSURL *url = [NSURL URLWithString:urlString]; request = [ASIFormDataRequest requestWithURL:url]; //设置缓存方式 //[request setSecondsToCache:60*60*24*30]; //[request setDownloadCache:[DFAppDelegate myCache]]; //设置缓存数据存储策略。这里採取的是假设无更新或无法联网就读取缓存数据 [request setCachePolicy:ASIAskServerIfModifiedCachePolicy|ASIFallbackToCacheIfLoadFailsCachePolicy]; [request setCacheStoragePolicy:ASICachePermanentlyCacheStoragePolicy]; [request setRequestMethod:@"GET"]; } request.delegate = self; request.timeOutSeconds = 60; [request startAsynchronous]; self.httpReq = request; self.urlString = urlString;}#pragma mark - ASIHTTPRequest delegate- (void)requestFinished:(ASIHTTPRequest *)request{ NSError *error = nil; if (request.responseStatusCode == 500) { // server状态500 error = [NSError errorWithDomain:@"server出错" code:-10000 userInfo:nil]; } id result = [NSJSONSerialization JSONObjectWithData:request.responseData options:NSJSONReadingMutableContainers error:nil]; if ([result isKindOfClass:[NSDictionary class]]) { NSString *status = [result objectForKey:@"status"]; if (![status isEqualToString:@"success"]) { // 请求返回errorCode error = [NSError errorWithDomain:[result objectForKey:@"info"] code:-9998 userInfo:nil]; } } else { error = [NSError errorWithDomain:@"server返回值出错" code:-9999 userInfo:nil]; } if ([[HttpClient sharedClient] respondsToSelector:@selector(didFinishWithItem:error:)]) { [[HttpClient sharedClient] performSelector:@selector(didFinishWithItem:error:) withObject:self withObject:error]; }}- (void)requestFailed:(ASIHTTPRequest *)request{ if ([[HttpClient sharedClient] respondsToSelector:@selector(didFinishWithItem:error:)]) { [[HttpClient sharedClient] performSelector:@selector(didFinishWithItem:error:) withObject:self withObject:request.error]; }}@end