ASIHTTPRequest框架使用总结系列之阿堂教程4（下载数据）

从本篇开始，阿堂准备进一步介绍ASIHTTPRequest框架下载数据和上传数据的实际应用。

为了实现多线程并发请求网络能力，ASIHTTPRequest被设计成 NSOperation的子类。ASINetworkQueue被设计成NSOpertaionQueue的子类。如果NSOpertaionQueue是线程管理器，NSOperation就相当于一个线程。它们被添加到NSOperationQueue队列中有序执行。ASINetworkQueue 和ASIHTTPRequest也有同样的概念，只是ASINetworkQueue线程管理器提供更多的与网络相关的服务，如获得下载进度等。所以，下面阿堂就主要介绍ASINetworkQueue管理请求队列的demo了。

下面，请随阿堂看一个例子介绍队列的用法。当我们点击go按钮时，从服务器端同时下载两张图片并将它们显示在界面中。

其中两个文件的完整源代码如下

ViewController.h, ViewController.m

#import

#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

---------------------------------------------------------

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad

{

[super viewDidLoad];

}

- (void)didReceiveMemoryWarning

{

[super didReceiveMemoryWarning];

}

- (IBAction)onClick:(id)sender {

if (!_networkQueue) {

_networkQueue = [[ASINetworkQueue alloc] init];

}

// 停止以前的队列

[_networkQueue cancelAllOperations];

// 创建ASI队列

[_networkQueue setDelegate:self];

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

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

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

for (int i=1; i<<span style="color: #272ad8">3; i++) {

NSString *strURL = [[NSString alloc] initWithFormat:@"http://www.crazyit.com/service/download.php?email=%@&FileName=test%i.jpg",@"heyitang@qq.com",i];

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

ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];

request.tag = i;

[_networkQueue addOperation:request];

}

[_networkQueue go];

}

- (void)requestFinished:(ASIHTTPRequest *)request

{

NSData *data = [request responseData];

// NSLog(@"data = %@",data);

NSError *eror;

NSDictionary *resDict = [NSJSONSerialization JSONObjectWithData:dataoptions:NSJSONReadingAllowFragments error:&eror];

//如果服务器是返回的图片过来，那是通过数据io流过来的，这里的 resDict值一定会为null, 因为 data不是json格式，所以NSJSONSerialization处理后是不能正解成json格式的。

NSLog(@"resDict = %@",resDict);

if (!resDict) {

UIImage *img = [UIImage imageWithData:data];

if (request.tag ==1) {

_imageView1.image = img;

} else {

_imageView2.image = img;

}

} else {

//如果是返回 json格式，一般类似于｛"ResultCode":-1｝格式，如果是图片io流返回，一定不是json格式返回了

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) {

[self setNetworkQueue:nil];

}

NSLog(@"请求成功");

}

- (void)requestFailed:(ASIHTTPRequest *)request

{

NSError *error = [request error];

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

if ([_networkQueue requestsCount] == 0) {

[self setNetworkQueue:nil];

}

NSLog(@"请求失败");

}

- (void)queueFinished:(ASIHTTPRequest *)request

{

if ([_networkQueue requestsCount] == 0) {

[self setNetworkQueue:nil];

}

NSLog(@"队列完成");

}

@end

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#import

@interface NSNumber (Message)

-(NSString *)errorMessage;

@end

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#import "NSNumber+Message.h"

@implementation NSNumber (Message)

-(NSString *)errorMessage

{

NSString *errorStr = @"";

switch ([self integerValue]) {

case -9:

errorStr = @"文件没有指定。";

break;

case -8:

errorStr = @"文件找不到。";

break;

case -7:

errorStr = @"没有数据。";

break;

case -6:

errorStr = @"日期没有输入。";

break;

case -5:

errorStr = @"内容没有输入。";

break;

case -4:

errorStr = @"ID没有输入。";

break;

case -3:

errorStr = @"据访问失败。";

break;

case -2:

errorStr = @"您的账号最多能插入10条数据。";

break;

case -1:

errorStr = @"用户不存在，请到http://www.crazyit.com注册。";

default:

break;

}

return errorStr;

}

@end