Python-通过urllib和python下载图片

Question

我正在尝试制作一个Python脚本，该脚本可以下载网络漫画并将其放入我桌面上的文件夹中。我在这里发现了一些类似的程序，它们的功能相似，但是却完全不符合我的需要。我发现最相似的代码就在这里（http://bytes.com/topic/python/answers/850927-problem-using-urllib-download-images）。我尝试使用此代码：

>>> import urllib
>>> image = urllib.URLopener()
>>> image.retrieve("http://www.gunnerkrigg.com//comics/00000001.jpg","00000001.jpg")
('00000001.jpg', <httplib.HTTPMessage instance at 0x1457a80>)

然后，我在计算机上搜索了文件“ 00000001.jpg”，但我发现的只是它的缓存图片。我什至不确定它是否已将文件保存到我的计算机中。一旦我了解了如何下载文件，我想我就会处理其余的事情。本质上，只需要使用for循环并在‘00000000’。’jpg’处拆分字符串，然后将‘00000000’递增至最大数，我必须以某种方式确定该数字。关于最佳方法或正确下载文件的任何建议？

这是完成的脚本，它将文件保存到你选择的任何目录中。由于某种奇怪的原因，文件没有下载，而只是下载了。任何有关如何清理它的建议将不胜感激。我目前正在研究如何查找网站上存在的许多漫画，因此我只能获取最新的漫画，而不是在引发一定数量的异常后退出程序。

import urllib
import os

comicCounter=len(os.listdir('/file'))+1  # reads the number of files in the folder to start downloading at the next comic
errorCount=0

def download_comic(url,comicName):
    """
    download a comic in the form of

    url = http://www.example.com
    comicName = '00000000.jpg'
    """
    image=urllib.URLopener()
    image.retrieve(url,comicName)  # download comicName at URL

while comicCounter <= 1000:  # not the most elegant solution
    os.chdir('/file')  # set where files download to
        try:
        if comicCounter < 10:  # needed to break into 10^n segments because comic names are a set of zeros followed by a number
            comicNumber=str('0000000'+str(comicCounter))  # string containing the eight digit comic number
            comicName=str(comicNumber+".jpg")  # string containing the file name
            url=str("http://www.gunnerkrigg.com//comics/"+comicName)  # creates the URL for the comic
            comicCounter+=1  # increments the comic counter to go to the next comic, must be before the download in case the download raises an exception
            download_comic(url,comicName)  # uses the function defined above to download the comic
            print url
        if 10 <= comicCounter < 100:
            comicNumber=str('000000'+str(comicCounter))
            comicName=str(comicNumber+".jpg")
            url=str("http://www.gunnerkrigg.com//comics/"+comicName)
            comicCounter+=1
            download_comic(url,comicName)
            print url
        if 100 <= comicCounter < 1000:
            comicNumber=str('00000'+str(comicCounter))
            comicName=str(comicNumber+".jpg")
            url=str("http://www.gunnerkrigg.com//comics/"+comicName)
            comicCounter+=1
            download_comic(url,comicName)
            print url
        else:  # quit the program if any number outside this range shows up
            quit
    except IOError:  # urllib raises an IOError for a 404 error, when the comic doesn't exist
        errorCount+=1  # add one to the error count
        if errorCount>3:  # if more than three errors occur during downloading, quit the program
            break
        else:
            print str("comic"+ ' ' + str(comicCounter) + ' ' + "does not exist")  # otherwise say that the certain comic number doesn't exist
print "all comics are up to date"  # prints if all comics are downloaded

Answer 1

使用urllib.urlretrieve：

import urllib
urllib.urlretrieve("http://www.gunnerkrigg.com//comics/00000001.jpg", "00000001.jpg")