IOS开发网络篇之──ASIHTTPRequest下载示例(支持断点续传)

SoccerZZM 2011-08-16

    一、创建网络请求队列

    首先,创建网络请求队列,如下:

    ASINetworkQueue   *que = [[ASINetworkQueue alloc] init];

    self.netWorkQueue = que;

    [que release];

    [self.netWorkQueue reset];

    [self.netWorkQueue setShowAccurateProgress:YES];

    [self.netWorkQueue go];

  二、创建存放路径

    //初始化Documents路径

NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];

//初始化临时文件路径

NSString *folderPath = [path stringByAppendingPathComponent:@"temp"];

//创建文件管理器

NSFileManager *fileManager = [NSFileManager defaultManager];

//判断temp文件夹是否存在

BOOL fileExists = [fileManager fileExistsAtPath:folderPath];

if (!fileExists) {//如果不存在说创建,因为下载时,不会自动创建文件夹

[fileManager createDirectoryAtPath:folderPath 

               withIntermediateDirectories:YES 

                                attributes:nil

                                     error:nil];

}

        三、发送下载请求

        这里对下面几个对象说明一下:CustomCell是我自定义的cell,cell上面有下载和暂停两个按钮,其tag值为cell所在的行,因此这里的[sendertag]为下载按钮的tag值,self.downloadArray为array数组对象,存放要下载的资源字典信息,在该字典中有一键为URL,它对应的值就是我们下载链接。

   这些东西,根据自己的实际需要改动一下即可使用

    CustomCell *cell = (CustomCell *)[self.myTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:[sender tag] inSection:0]];

    NSString  *filePath = [[self.downloadArray objectAtIndex:[sender tag]] objectForKey:@"URL"];

    NSLog(@"filePath=%@",filePath);

    //初始下载路径

NSURL *url = [NSURL URLWithString:filePath];

//设置下载路径

ASIHTTPRequest *request = [[ASIHTTPRequest alloc] initWithURL:url];

//设置ASIHTTPRequest代理

request.delegate = self;

    //初始化保存ZIP文件路径

NSString *savePath = [path stringByAppendingPathComponent:[NSString stringWithFormat:@"book_%d.zip",[sender tag]]];

//初始化临时文件路径

NSString *tempPath = [path stringByAppendingPathComponent:[NSString stringWithFormat:@"temp/book_%d.zip.temp",[sender tag]]];

//设置文件保存路径

[request setDownloadDestinationPath:savePath];

//设置临时文件路径

[request setTemporaryFileDownloadPath:tempPath];

    //设置进度条的代理,

[request setDownloadProgressDelegate:cell];

//设置是是否支持断点下载

[request setAllowResumeForFileDownloads:YES];

//设置基本信息

[request setUserInfo:[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithInt:[sender tag]],@"bookID",nil]];

    NSLog(@"UserInfo=%@",request.userInfo);

//添加到ASINetworkQueue队列去下载

[self.netWorkQueue addOperation:request];

//收回request

[request release];

    三、暂停请求

    这里的cell下下载时的一样,

CustomCell *cell = (CustomCell *)[self.myTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:[sender tag] inSection:0]];

    for (ASIHTTPRequest *request in [self.netWorkQueue operations]) {

        NSInteger bookid = [[request.userInfo objectForKey:@"bookID"] intValue];//查看userinfo信息

        if ([sender tag] == bookid) {//判断ID是否匹配

            //暂停匹配对象

            [request clearDelegatesAndCancel];

        }

    }

    四、ASIHTTPRequestDelegate回调方法

          上面已经把下载请求与暂停请求实现,点击下载时,开始下载资源;当点暂停时,下载中断;当我们再点击下载按钮时,继续下载,在第二步的

[request setAllowResumeForFileDownloads:YES]设置是是否支持断点下载。下面要实现ASIHTTPRequestDelegate代理方法如下:

#pragma mark -

#pragma mark ASIHTTPRequestDelegate method

//ASIHTTPRequestDelegate,下载之前获取信息的方法,主要获取下载内容的大小,可以显示下载进度多少字节

- (void)request:(ASIHTTPRequest *)request didReceiveResponseHeaders:(NSDictionary *)responseHeaders {

NSLog(@"didReceiveResponseHeaders-%@",[responseHeaders valueForKey:@"Content-Length"]);

    NSLog(@"contentlength=%f",request.contentLength/1024.0/1024.0);

    int bookid = [[request.userInfo objectForKey:@"bookID"] intValue];

    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

    float tempConLen = [[userDefaults objectForKey:[NSString stringWithFormat:@"book_%d_contentLength",bookid]] floatValue];

    NSLog(@"tempConLen=%f",tempConLen);

    //如果没有保存,则持久化他的内容大小

    if (tempConLen == 0 ) {//如果没有保存,则持久化他的内容大小

        [userDefaults setObject:[NSNumber numberWithFloat:request.contentLength/1024.0/1024.0] forKey:[NSString stringWithFormat:@"book_%d_contentLength",bookid]];

    }

}

//ASIHTTPRequestDelegate,下载完成时,执行的方法

- (void)requestFinished:(ASIHTTPRequest *)request {

    int bookid = [[request.userInfo objectForKey:@"bookID"] intValue];

    CustomCell *cell = (CustomCell *)[self.myTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:bookid inSection:0]];

    cell.downloadCompleteStatus = YES;

    cell.progressView.progress = 0.0; 

}

    经过上述步骤,一个支持断点续传的功能程序实现了!

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