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 <NSObject>
- (void)requestWillBegin;
- (void)requestDidSucceedWithData:(id)data;
- (void)requestDidFailWithError:(NSError *)error;
@end
@interface RequestService : NSObject
@property (nonatomic,assign)id<RequestServiceDelegate> delegate;
- (void)requestWithUrlString:(NSString *)urlString
params:(NSDictionary *)params
httpMethod:(NSString *)httpMethod;
@end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。
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 <NSObject>
- (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<HttpClientDelegate>)delegate;
@end使用例如以下：[[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<HttpClientDelegate>)delegate
{
HttpRequestItem *item = [[HttpRequestItem alloc] init];
item.delegate = delegate;
[item requestWithUrlString:urlString params:params httpMethod:httpMethod];
NSUInteger hashValue = [item hash];
[self.items addObject:item];
}用于接收RequestItem的通知方法例如以下：- (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
#import <Foundation/Foundation.h>
@protocol HttpClientDelegate <NSObject>
- (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<HttpClientDelegate>)delegate;
- (NSUInteger)requestWithUrl:(NSString *)urlString
params:(NSDictionary *)params
httpMethod:(NSString *)httpMethod
delegate:(id<HttpClientDelegate>)delegate
nTag:(NSInteger)nTag;
- (NSUInteger)requestWithUrl:(NSString *)urlString
params:(NSDictionary *)params
httpMethod:(NSString *)httpMethod
delegate:(id<HttpClientDelegate>)delegate
sKey:(NSString *)sKey;
- (NSUInteger)requestWithUrl:(NSString *)urlString
params:(NSDictionary *)params
httpMethod:(NSString *)httpMethod
delegate:(id<HttpClientDelegate>)delegate
nTag:(NSInteger)nTag
sKey:(NSString *)sKey;
// 取消请求
- (BOOL)cancelRequestWithHashValue:(NSUInteger)hashValue;
@endHttpClient.m#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<HttpClientDelegate>)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<HttpClientDelegate>)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<HttpClientDelegate>)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<HttpClientDelegate>)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 <Foundation/Foundation.h>
#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<HttpClientDelegate> 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
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