ASIHTTPRequest 断点续传

最近学习ASIHTTPRequest如何使用,所以利用ASIHTTPRequest自身的功能,写了个可断点下载的小demo

我利用tableview作为下载列表,所有自己custom了一个cell,用来控制下载

enum DownloadStatus {    DownloadNotStart = 0,    Downloading,    DownloadPause,    DownloadFinish};@interface DownloadFileListTableViewCell : UITableViewCell <ASIHTTPRequestDelegate, ASIProgressDelegate>{    UIProgressView *_progressView;    UIButton *_controlButton;    UILabel *_sizeTip;        ASIHTTPRequest *_asiRequest;    NSURL *_oriURL;    enum DownloadStatus _downloadStatus;    NSString *_saveFilePath;    NSString *_tmpFilePath;        long long _curSize;    long long _totalSize;}

最新的 ASIHTTPRequest 自己有一个支持断点下载的方法,

    [_asiRequest setTemporaryFileDownloadPath:_tmpFilePath];    [_asiRequest setAllowResumeForFileDownloads:YES];

只要设置了这两个,就可以实现断点下载

下面是我自己实现的几个控制下载的方法

- (void)startDownload{    _curSize = 0;    _totalSize = 0;        _asiRequest = [[ASIHTTPRequest alloc] initWithURL:_oriURL];    [_asiRequest setDelegate:self];    [_asiRequest setDownloadProgressDelegate:self];    [_asiRequest setShowAccurateProgress:YES];    [_asiRequest setDownloadDestinationPath:_saveFilePath];    [_asiRequest setTemporaryFileDownloadPath:_tmpFilePath];    [_asiRequest setAllowResumeForFileDownloads:YES];        _downloadStatus = Downloading;    [_controlButton setTitle:@"Pause" forState:UIControlStateNormal];    [_asiRequest startAsynchronous];}- (void)pauseDownload{    [_asiRequest clearDelegatesAndCancel];    [_asiRequest release], _asiRequest = nil;    _downloadStatus = DownloadPause;    [_controlButton setTitle:@"Resume" forState:UIControlStateNormal];}- (void)resumeDownload{    _curSize = 0;        _asiRequest = [[ASIHTTPRequest alloc] initWithURL:_oriURL];    [_asiRequest setDelegate:self];    [_asiRequest setDownloadProgressDelegate:self];    [_asiRequest setShowAccurateProgress:YES];    [_asiRequest setDownloadDestinationPath:_saveFilePath];    [_asiRequest setTemporaryFileDownloadPath:_tmpFilePath];    [_asiRequest setAllowResumeForFileDownloads:YES];        _downloadStatus = Downloading;    [_controlButton setTitle:@"Pause" forState:UIControlStateNormal];    [_asiRequest startAsynchronous];}- (void)finishDownload{    [_controlButton setTitle:@"Finish" forState:UIControlStateNormal];    _downloadStatus = DownloadFinish;    NSLog(@"success Finish Download");}

因为要利用progressview手动记录下载情况,所以,继承了ASIProgressDelegate,并实现了

- (void)request:(ASIHTTPRequest *)request didReceiveBytes:(long long)bytes{    // when resume download, the bytes is the size of the file which had down    _curSize += bytes;        float value = (_curSize*1.0)/(_totalSize*1.0);    [_progressView setProgress:value];        float tmp = 1024*1024.0;    NSString *tip = [NSString stringWithFormat:@"%.1lf/%.1lfM", _curSize/tmp, _totalSize/tmp];    [_sizeTip setText:tip];}

这样,就可以随时记录下载情况了.

写这个demo的过程中,还遇到了url redirect的问题,ASIHTTPRequest本身是可以auto redirect的,但是不知什么原因,我这里并没有auto redirect,所以,我自己手动控制它redirect(实现ASIHTTPRequestDelegate的requestFailed方法)

- (void)requestFailed:(ASIHTTPRequest *)request{    NSError *error = [request error];    [_controlButton setTitle:@"Fail" forState:UIControlStateNormal];    NSLog(@"Failed error : %@", [error localizedDescription]);        NSDictionary *resp = [request responseHeaders];    NSString *redirectURL = [resp valueForKey:@"Location"];    if([request responseStatusCode] == 302 && redirectURL){        [self redirectToDest:redirectURL];    }}

当然,status code = 301的时候也需要redirect,我这里就没加上了.

到这里,我还遇到个问题就是,每次下载都定死了文件名,当下载多个文件时,会导致文件重写,所以,要时不同文件不重复,且能很好的辨认,最后的办法就是能从头部中获取服务端返回的文件名,并以此命名.但是,在ASIHTTPRequet的responseHeader中却找不到这个值.经google后得知,需要自己解析header 的 Content-Disposition.所以,我想获取ASIHTTPRequest刚获取的header,不知怎么获取.

来源：https://www.cnblogs.com/mew7wo/archive/2011/10/09/2203381.html

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断点续传