php - Alamofire 下载文件存在进度问题

Question

我想从服务器下载一个有进度的文件。这是我尝试过的代码:

let destination: (NSURL, NSHTTPURLResponse) -> (NSURL) = {
    (temporaryURL, response) in
    if let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as? NSURL {
        let path = directoryURL.URLByAppendingPathComponent(response.suggestedFilename!)
        return path
    }
    return temporaryURL
}

Alamofire.download(.GET, fileUrls[button.tag], destination: destination)
.progress { _, totalBytesRead, totalBytesExpectedToRead in
    dispatch_async(dispatch_get_main_queue()) {
        println("\(Float(totalBytesRead)) - \(Float(totalBytesExpectedToRead))")

        if totalBytesRead == totalBytesExpectedToRead {
            println("******************************")
            println("finished")
            println("******************************")
        }
    }
}
.response { (_, _, data, error) in
    println(data)
    println(error)
}

但是totalBytesExpectedToRead始终为-1。我搜索了这个问题，发现服务器端的Content-Length没有设置。

我尝试过设置，但似乎不起作用:

$attachment_location = $_GET["filepath"];
if (file_exists($attachment_location)) {
    header('Content-Description: File Transfer');
    header('Content-Type:' . mime_content_type($attachment_location));
    header('Content-Disposition: attachment; filename='.basename($attachment_location));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($attachment_location));
    readfile($attachment_location);
    die(); 
} else {
    die("Error: File not found.");
}

有人可以告诉我我做错了什么吗？谢谢。

Answer 1

通过将代码更改为以下内容来解决:

$attachment_location = $_GET["filepath"];
if (file_exists($attachment_location)) {
    header('Content-Description: File Transfer');
    header('Content-Type:' . mime_content_type($attachment_location));
    header('Content-Disposition: attachment; filename='.basename($attachment_location));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Encoding: chunked');
    header('Content-Length: ' . filesize($attachment_location), true);
    readfile($attachment_location);
    die(); 
} else {
    die("Error: File not found.");
}