# -*- coding: utf-8 -*- # Author: ToughGuy # Email: wj0630@gmail.com # 写这玩意儿是为了初步了解下python的多线程机制 # 平时没写注释的习惯, 这次花时间在代码里面写上注释也是希望有问题的地方请各位指正, 因为可能我自己也没弄明白. # 测试平台 Ubuntu 13.04 X86_64 Python 2.7.4 import threading import urllib2 import sys max_thread = 10 # 初始化锁 lock = threading.RLock() class Downloader(threading.Thread):     def __init__(self, url, start_size, end_size, fobj, buffer):         self.url = url         self.buffer = buffer         self.start_size = start_size         self.end_size = end_size         self.fobj = fobj         threading.Thread.__init__(self)     def run(self):         """             马甲而已         """         with lock:             print 'starting: %s' % self.getName()         self._download()     def _download(self):         """             我才是搬砖的         """         req = urllib2.Request(self.url)         # 添加HTTP Header(RANGE)设置下载数据的范围         req.headers['Range'] = 'bytes=%s-%s' % (self.start_size, self.end_size)         f = urllib2.urlopen(req)         # 初始化当前线程文件对象偏移量         offset = self.start_size         while 1:             block = f.read(self.buffer)             # 当前线程数据获取完毕后则退出             if not block:                 with lock:                     print '%s done.' % self.getName()                 break             # 写如数据的时候当然要锁住线程             # 使用 with lock 替代传统的 lock.acquire().....lock.release()             # 需要python >= 2.5             with lock:                 sys.stdout.write('%s saveing block...' % self.getName())                 # 设置文件对象偏移地址                 self.fobj.seek(offset)                 # 写入获取到的数据                 self.fobj.write(block)                 offset = offset + len(block)                 sys.stdout.write('done.\n') def main(url, thread=3, save_file='', buffer=1024):     # 最大线程数量不能超过max_thread     thread = thread if thread <= max_thread else max_thread     # 获取文件的大小     req = urllib2.urlopen(url)     size = int(req.info().getheaders('Content-Length')[0])     # 初始化文件对象     fobj = open(save_file, 'wb')     # 根据线程数量计算 每个线程负责的http Range 大小     avg_size, pad_size = divmod(size, thread)     plist = []     for i in xrange(thread):         start_size = i*avg_size         end_size = start_size + avg_size - 1         if i == thread - 1:             # 最后一个线程加上pad_size             end_size = end_size + pad_size + 1         t = Downloader(url, start_size, end_size, fobj, buffer)         plist.append(t)     #  开始搬砖     for t in plist:         t.start()     # 等待所有线程结束     for t in plist:         t.join()     # 结束当然记得关闭文件对象     fobj.close()     print 'Download completed!' if __name__ == '__main__':     url = 'http://192.168.1.2:8082/downloads/10M.zip'     main(url=url, thread=10, save_file='test.iso', buffer=4096)