Python URL检索限制率并恢复部分下载

Question

我正在使用此线程中的代码来限制下载速度。

如何合并使用限速代码恢复的部分下载？我发现的示例urlopen代替urlretrieve，而RateLimit类取决于urlretrieve。

我想要一个外部函数来控制部分下载，而无需更改RateLimit类：

from throttle import TokenBucket, RateLimit

def retrieve_limit_rate(url, filename, rate_limit):
    """Fetch the contents of urls"""
    bucket = TokenBucket(10*rate_limit, rate_limit)

    print "rate limit = %.1f kB/s" % (rate_limit,)

    print 'Downloading %s...' % filename
    rate_limiter = RateLimit(bucket, filename)
    #
    # What do I put here to allow resuming files?
    #
    return urllib.urlretrieve(url, filename, rate_limiter)

Answer 1

也许可以使用PyCurl代替：

def curl_progress(total, existing, upload_t, upload_d):
    try:
        frac = float(existing)/float(total)
    except:
        frac = 0
    print "Downloaded %d/%d (%0.2f%%)" % (existing, total, frac)

def curl_limit_rate(url, filename, rate_limit):
    """Rate limit in bytes"""
    import pycurl
    c = pycurl.Curl()
    c.setopt(c.URL, url)
    c.setopt(c.MAX_RECV_SPEED_LARGE, rate_limit)
    if os.path.exists(filename):
        file_id = open(filename, "ab")
        c.setopt(c.RESUME_FROM, os.path.getsize(filename))
    else:
        file_id = open(filename, "wb")

    c.setopt(c.WRITEDATA, file_id)
    c.setopt(c.NOPROGRESS, 0)
    c.setopt(c.PROGRESSFUNCTION, curl_progress)
    c.perform()