ASINetworkQueue 队列下载

我们通过一个例子介绍一下请求队列使用，我们设计了一个应用，用户点击GO按钮从服务器同时下载两张图片显示在画面中。 

我们直接看看主视图控制器ViewController.h代码如下： 

#import “ASIHTTPRequest.h” 

#import “ASINetworkQueue.h” 

#import “NSNumber+Message.h” 

#import “NSString+URLEncoding.h” 



@interface ViewController : UIViewController 



@property (weak, nonatomic) IBOutlet UIImageView *imageView1; 

@property (weak, nonatomic) IBOutlet UIImageView *imageView2; 

@property (strong) ASINetworkQueue *networkQueue; 



- (IBAction)onClick:(id)sender; 

@end 

我们需要引入ASI框架的两个头文件ASIHTTPRequest.h和ASINetworkQueue.h。其中imageView1和 imageView2是与画面对应的两个图片视图控件。还定义了ASINetworkQueue 类型的networkQueue属性。我们直接看看主视图控制器ViewController.m中点击GO按钮调用方法，代码如下： 

- (IBAction)onClick:(id)sender { 

if (!_networkQueue) { 

_networkQueue = [[ASINetworkQueue alloc] init]; ① 

} 

// 停止以前的队列 

[_networkQueue cancelAllOperations]; ② 

// 创建ASI队列 

[_networkQueue setDelegate:self]; 

[_networkQueue setRequestDidFinishSelector:@selector(requestFinished:)]; ③ 

[_networkQueue setRequestDidFailSelector:@selector(requestFailed:)]; ④ 

[_networkQueue setQueueDidFinishSelector:@selector(queueFinished:)]; ⑤ 



for (int i=1; i<3; i++) { 

NSString *strURL = [[NSString alloc] initWithFormat: 

@”http://iosbook3/download.php?email=%@&FileName=test%i.jpg”, 

@”<你的iosbook1.com用户邮箱>”,i]; 

NSURL *url = [NSURL URLWithString:[strURL URLEncodedString]]; 

ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url]; 

request.tag = i; ⑥ 

[_networkQueue addOperation:request]; ⑦ 

} 

[_networkQueue go]; ⑧ 

} 

我们再看看它们的回调方法，代码： 

- (void)requestFinished:(ASIHTTPRequest *)request 

{ 

NSData *data = [request responseData]; 

NSError *eror; 

NSDictionary *resDict = [NSJSONSerialization JSONObjectWithData:data 

options:NSJSONReadingAllowFragments error:&eror]; 

if (!resDict) { 

UIImage *img = [UIImage imageWithData:data]; 

if (request.tag ==1) { ① 

_imageView1.image = img; 

} else { 

_imageView2.image = img; 

} 

} else { 

NSNumber *resultCodeObj = [resDict objectForKey:@"ResultCode"]; 

NSString *errorStr = [resultCodeObj errorMessage]; 

UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@”错误信息” 

message:errorStr 

delegate:nil 

cancelButtonTitle:@”OK” 

otherButtonTitles: nil]; 

[alertView show]; 

} 

if ([_networkQueue requestsCount] == 0) { ② 

[self setNetworkQueue:nil]; 

} 

NSLog(@”请求成功”); 

} 

- (void)requestFailed:(ASIHTTPRequest *)request ③ 

{ 

NSError *error = [request error]; 

NSLog(@”%@”,[error localizedDescription]); 

if ([_networkQueue requestsCount] == 0) { 

[self setNetworkQueue:nil]; 

} 

NSLog(@”请求失败”); 

} 

- (void)queueFinished:(ASIHTTPRequest *)request ④ 

{ 

if ([_networkQueue requestsCount] == 0) { 

[self setNetworkQueue:nil]; 

} 

NSLog(@”队列完成”); 

} 

requestFinished:方法是请求对象成功回调方法，因此有两个请求对象它会被调用两次，在第①行代码中我们根据GO按钮点击事件设定的 请求对象的tag属性，来判断是哪个请求对象的回调。进而加载到显示不同的图片视图。第②代码[_networkQueue requestsCount]可以判断队列中请求对象的个数。

 

 

//其他。。。

[networkQueueForSong reset];

//下载队列代理方法

[networkQueueForSong setRequestDidFailSelector:@selector(singleDownLoadFail:)];

[networkQueueForSong setRequestDidFinishSelector:@selector(singleDownloadFinished:)];

[networkQueueForSong setRequestDidReceiveResponseHeadersSelector:@selector(downLoadReceiveResponseHeader:)];

[networkQueueForSong setRequestDidStartSelector:@selector(singleDownLoadStart:)];

[networkQueueForSong setQueueDidFinishSelector:@selector(downLoadFinish)];

[networkQueueForSong setDelegate:self];

//设置下载队列属性，设置为1只允许下完一首再下另一首，默认是并行下载不分前后

[networkQueueForSong setMaxConcurrentOperationCount:1];