ASIHTTPRequest下载示例（支持断点续传）

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！