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 Threadclass 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 = threadnameself.url = urlself.filename = filenameself.ranges = rangesself.downloaded = 0def run(self):"""virtual function in Thread"""try:self.downloaded = os.path.getsize(self.filename)except OSError:self.downloaded = 0#rebuild start pointself.startpoint = self.ranges[0] + self.downloaded#if this part is completedif self.startpoint >= self.ranges[1]:print 'Part %s has been downloaded over.' % self.filenamereturnself.oneTimeSize = 8 * 1024 #8K bytes / timeprint '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().headerslength = 0for header in headers:if header.find('Length') != -1:length = header.split(':')[-1].strip()length = int(length)return length
def SpliteBlocks(totalsize, blocknumber):blocksize = totalsize / blocknumberranges = []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 Truereturn 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) * 100show = u'\rFilesize: %d Downloaded:%d Completed: %.2f%%' %(size, downloaded, process)sys.stdout.write(show)sys.stdout.flushtime.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 filenamereturn filenameelse: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 fullURLmp3Names = findMP3FileInURL(fullURL)if len(mp3Names) == 1:#there is only on mp3 file in this file ,so we will use the formatednameneededDownloadMp3s[formatedName] = mp3Names[0]else:for name in mp3Names:print nameindex_begin = name.rfind('/')index_end = name.rfind('.')tmpName = name[index_begin + 1 : index_end]neededDownloadMp3s[tmpName] = nameprint '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 filefor 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(), exprint '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。
