python 自动下载 voa MP3

因为英语学习的需要，经常会去网上下载一些VOA的MP3，常去的一个网站是http://www.51voa.com/

要想下载该网站上的MP3，需要手动选择要下载的篇幅，打开之后再选择要下载的MP3文件。要下载单独一个MP3文件还好，但要是想把某一时间内的所有MP3文件都下载下来，就很繁琐，需要重复做那些无聊的操作。能否用python来做一个下载voa MP3的工具呢？

设计思路如下：

一、打开http://www.51voa.com/主页，分析html，解析出主页上 VOA美国之音听力最近更新 文件列表，生成<文件名，文件下载地址>的dictionary

二、对已生成的dictionary按照当前日期过滤，得到能下载的当天的VOA MP3

三、对过滤后的dictionary遍历，同时进行下载操作

其中所使用的技术：

一、解析html，可以使用standar library中的HTMLParser，或者SGMLParser，也可以选择3rd party的解析库，比如BeautifulSoup（对html和xml都能很好的支持），本文采用BeautifulSoup

二、下载MP3，采用urllib，为提高效率，使用多线程进行下载，url header中可以使用Range参数分片下载，这样一来就能多部分协同操作。

具体代码如下：

一、多线程下载部分代码

#!/usr/bin/env python

# -*- coding :utf-8 -*-
"""
 It is a multi-thread downloading tool
"""

import sys
import os
import time
import urllib2
import urllib
from threading import Thread

class MyWorkThread(Thread, urllib.FancyURLopener):
    """
    Multi-thread downloading class.
    run() is a vitual method of Thread
    """
    def __init__(self, threadname, url, filename, ranges = 0):
        Thread.__init__(self, name = threadname)
        urllib.FancyURLopener.__init__(self)
        self.name = threadname
        self.url = url
        self.filename = filename
        self.ranges = ranges
        self.downloaded = 0
    def run(self):
        """
        virtual function in Thread
        """
        try:
            self.downloaded = os.path.getsize(self.filename)
        except OSError:
            self.downloaded = 0
        #rebuild start point
        self.startpoint = self.ranges[0] + self.downloaded
        
        #if this part is completed
        if self.startpoint >= self.ranges[1]:
            print 'Part %s has been downloaded over.' % self.filename
            return
        self.oneTimeSize = 8 * 1024 #8K bytes / time
        print 'task %s will download from %d to %d' %(self.name, self.startpoint, self.ranges[1])
        self.addheader('Range', 'bytes=%d-%d' %(self.startpoint, self.ranges[1]))
        self.urlhandle = self.open(self.url)
        data = self.urlhandle.read(self.oneTimeSize)
        while data:
            filehandle = open(self.filename, 'ab+')
            filehandle.write(data)
            filehandle.close()
            self.downloaded += len(data)
            data = self.urlhandle.read(self.oneTimeSize)
            
def GetUrlFileSize(url):
    urlHandler = urllib.urlopen(url)
    headers = urlHandler.info().headers
    length = 0
    for header in headers:
        if header.find('Length') != -1:
            length = header.split(':')[-1].strip()
            length = int(length)
    return length
def SpliteBlocks(totalsize, blocknumber):
    blocksize = totalsize / blocknumber
    ranges = []
    for i in range(0, blocknumber -1):
        ranges.append((i * blocksize, i * blocksize + blocksize -1))
    ranges.append((blocksize * (blocknumber -1), totalsize -1))
    return ranges
def isLive(tasks):
    for task in tasks:
        if task.isAlive():
            return True
    return False
def downLoadFile(url, output, blocks = 6):
    sys.stdout.write('Begin to download from %s\n' %url )
    sys.stdout.flush()
    size = GetUrlFileSize(url)
    ranges = SpliteBlocks(size, blocks)
    
    threadname = ["thread_%d" %i for i in range(0, blocks)]
    filename = ["tmpfile_%d" %i for i in range(0, blocks)]
    tasks = []
    for i in range(0, blocks):
        task = MyWorkThread(threadname[i], url, filename[i], ranges[i])
        task.setDaemon(True)
        task.start()
        tasks.append(task)
    time.sleep(2)
    while isLive(tasks):
        downloaded = sum([task.downloaded for task in tasks])
        process = downloaded / float(size) * 100
        show = u'\rFilesize: %d Downloaded:%d Completed: %.2f%%' %(size, downloaded, process)
        sys.stdout.write(show)
        sys.stdout.flush
        time.sleep(1)
        
    output = formatFileName(output)
    filehandle = open(output, 'wb+')
    for i in filename:
        f = open(i, 'rb')
        filehandle.write(f.read())
        f.close()
        os.remove(i)
    filehandle.close()
    sys.stdout.write("Completed!\n")
    sys.stdout.flush()
        
def formatFileName(filename):
    if isinstance(filename, str):
        header, tail = os.path.split(filename)
        if tail != '':
            tuple = ('\\','/',':', '*', '?', '"', '<', '>', '|')
            for char in tuple:
                if tail.find(char) != -1:
                    tail = tail.replace(char, '')
        filename = os.path.join(header, tail)
        #print filename
        return filename
    else:
        return 'None'
    
if __name__ == '__main__':
    url = r'http://www.51voa.com/path.asp?url=/201008/hennessy_africa_wildlife_18aug10-32b.mp3'
    output = r"D:\Voa\Study:'Shoot to Kill' Policy in Africa's Parks Abuses Human Rights.mp3"
    downLoadFile(url, output, blocks = 4)

二、解析voa页面部分代码

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import urllib2
import chardet
import os
import time
import string
import re
from HTMLParser import HTMLParser
import sys
from BeautifulSoup import BeautifulSoup
import multiThreadDownloadTool


VOA_URL = r'http://www.51voa.com'
DOWNLOAD_DIR = r'D:/Voa'

"""
File downloading from the web.
"""

def getURLContent(url):
    """
    get url content of the url, begin with html and ignor the doctype declarations
    """
    file = urllib2.urlopen(url)
    #print file.info()
    data = file.read()
    file.close()
    #return data.decode('utf-8')
    index = data.find('html')
    data = data[index - 1 :]
    return data
def getVOAURLs(content):
    """
    find the voa script urls in the content
    """
    urls = {}
    soup = BeautifulSoup(content)
    divs = soup.findAll('div', {'id':'rightContainer'})
    #print divs
    neededDiv = None
    if len(divs) >= 1:
        neededDiv = divs[0]
    if neededDiv != None:
        #pass the div
        #print neededDiv
        neededSpan = neededDiv.find('span', {'id' : 'list'})
        #print neededSpan
        lis = neededSpan.findAll('li')
        #print lis
        for li in lis:
            needAs = li.findAll('a')
            #got it
            #print needAs[1]
            #print needAs[1]['href']
            #print needAs[-1].string
            urls[needAs[-1].string] = VOA_URL + needAs[-1]['href']
    print "getVOAURLs() urls count is " , len(urls)
    return urls
def filterbyDate(urls ,date):
    """
    filter the urls by date
    """
    neededURLs = {}
    currentDate = time.localtime(time.time());
    #currentDateStr = time.strftime('%Y-%m-%d', currentDate)
    #currentDateStr = currentDate.tm_year + '-' + currentDate.tm_mon + ' ' + currentDate.tm_mday
    currentDateStr = "%s-%s-%s"  %(currentDate.tm_year, currentDate.tm_mon, currentDate.tm_mday)
    if(date != None):
        currentDateStr = date
    for url in urls.keys():
        name = url.lstrip().rstrip()
        length = len(name)
        publishDate = name[- len(currentDateStr) - 1 : -1]
        #print publishDate
        if publishDate == currentDateStr:
            neededURLs[name] = urls[url]
            print 'find ', name
    
    print 'After filter, the count is ' , len(neededURLs)
    return neededURLs

def findMP3FileInURL(url):
    """
    find MP3 files in a url
    """
    print 'parse the content of ', url
    urls = []
    #define a MP3 re string
    p = re.compile(r'/path.asp\?url=[-\w/]*\.mp3')
    #p = re.compile(r'/[-\w/]*\.mp3')
    content = getURLContent(url)
    matchLinks = p.findall(content)
    #print matchLinks
    for link in matchLinks:
        tmp = VOA_URL + link
        if tmp in urls: # check if exist already
            pass
        else:
            urls.append(tmp)
    print 'Current count of mp3 files is ', len(urls)
    return urls
def getHTMLFile(url, file_name):
    ifile = urllib2.urlopen(url)
    content = ifile.read()
    local_file = open(file_name, 'w')
    local_file.write(content)
    local_file.close()
    
def downloadFile(url, fileName2Store):
    """
    download file from url, and store it to local system using fileName2Store parameter
    """
    try:
        full_path = os.path.join(DOWNLOAD_DIR, fileName2Store)
        print 'begin to download url to ', full_path
        if os.path.isfile(full_path):
            #already exist
            print 'the file ', full_path, 'is alreasy exist, so just skip it!'
        else:
            print '\tDownloading the mp3 file...',  
            data=urllib2.urlopen(url).read()  
            print 'Done'  
            print '\tWriting data info file...',  
            f=file(full_path, 'wb')  
            f.write(data)  
            print 'Done'  
            f.close()
    except Exception, ex:
        print 'some exceptions occur when downloading ', ex
if __name__ == "__main__":
    try:
        #getHTMLFile(VOA_URL, r'.\Voa.html')
        context = getURLContent(VOA_URL)
        #file_read = open(r'.\Voa.html', 'r')
        #context = file_read.read()
        #print context
        #print '\n' * 5
        #print chardet.detect(context)
        print 'Begin to get download information, it may cost some minuts, please wait...'
        files2download = getVOAURLs(context)
        neededDownload = filterbyDate(files2download, None)
        neededDownloadMp3s = {}
        for name in neededDownload.keys():
            fullURL = neededDownload[name]
            formatedName = name[: -11].lstrip().rstrip()
            #formatedName = formatedName.replace(' ', '-')
            #print formatedName, ' ' * 5, fullURL
            #print fullURL
            mp3Names = findMP3FileInURL(fullURL)
            if len(mp3Names) == 1:
                #there is only on mp3 file in this file ,so we will use the formatedname
                neededDownloadMp3s[formatedName] = mp3Names[0]
            else:
                for name in mp3Names:
                    print name
                    index_begin = name.rfind('/')
                    index_end = name.rfind('.')
                    tmpName = name[index_begin + 1 : index_end]
                    neededDownloadMp3s[tmpName] = name
        
        print 'Now , the mp3 files  are :'
        print neededDownloadMp3s
        
        #findMP3FileInURL(r'http://www.51voa.com/VOA_Special_English/Phoning-Fertilizer-Philippine-Rice-Farmers--38545.html')
        #findMP3FileInURL(r'http://www.51voa.com/Voa_English_Learning/Learn_A_Word_38412.html')
        
        #down load file
        for filename in neededDownloadMp3s.keys():
            try:
                full_path = os.path.join(DOWNLOAD_DIR, filename)
                full_path = full_path + r'.mp3'
                if full_path == r'D:\Voa\hennessy_africa_wildlife_18aug10-32b.mp3':
                    multiThreadDownloadTool.downLoadFile(neededDownloadMp3s[filename], full_path)
            except Exception, ex:
                print 'Some exceptions occur, when downloading file from %s, exception messages are %s' %(neededDownloadMp3s[filename], ex)
                #downloadFile(r'http://www.51voa.com/path.asp?url=/201008/mercer_australia_election_16aug10-32b.mp3', 'test.mp3')
    except Exception, ex:
        print 'Exception caught, tracebacks are :',sys.exc_info(), ex
    print 'download all completed!'
    raw_input("Press any key to continue...")
    

需要注意的地方：

在使用BeautifulSoup进行html解析的时候发现，BeautifulSoup对于

<!DOCTYPE html PUBliC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" />
 的支持不是很好，经常解析不出来，所以为了方便，在解析的时候先将源文件解析，只将<html></html>之间的数据交与BeautifulSoup解析。具体为什么BeautifulSoup解析
DOCTYPE出错，我还没查出问题所在，希望有知道的朋友告知一声。