# 文件名：ThreadDownload.py
import threading
from urllib.request import *


class Download:
  def __init__(self, link, file_path, thread_num):
    # 下载路径
    self.link = link
    # 保存位置
    self.file_path = file_path
    # 使用多少线程
    self.thread_num = thread_num
    # 初始化threads数组
    self.threads = []

  def download(self):
    req = Request(url=self.link, method='GET')
    req.add_header('Accept', '*/*')
    req.add_header('Charset', 'UTF-8')
    req.add_header('Connection', 'Keep-Alive')
    f = urlopen(req)
    # 获取要下载的文件的大小
    self.file_size = int(dict(f.headers).get('Content-Length', 0))
    f.close()
    # 计算每个线程要下载的资源的大小
    current_part_size = self.file_size // self.thread_num + 1
    for i in range(self.thread_num):
      # 计算每个线程下载的开始位置
      start_pos = i * current_part_size
      # 每个线程使用一个wb模式打开的文件进行下载
      t = open(self.file_path, 'wb')
      t.seek(start_pos, 0)
      # 创建下载线程
      td = ThreadDownload(self.link, start_pos, current_part_size, t)
      self.threads.append(td)
      td.start()

  # 获下载的完成百分比
  def get_complete_rate(self):
    sum_size = 0
    for i in range(self.thread_num):
      sum_size += self.threads[i].length
    return sum_size / self.file_size

class ThreadDownload(threading.Thread):
  def __init__(self, link, start_pos, current_part_size, current_part):
    super().__init__() 
    # 下载路径
    self.link = link
    # 当前线程的下载位置
    self.start_pos = start_pos
    # 定义当前线程负责下载的文件大小
    self.current_part_size = current_part_size
    # 当前文件需要下载的文件快
    self.current_part = current_part
    # 定义该线程已经下载的字节数
    self.length = 0
  
  def run(self):
    req = Request(url = self.link, method='GET')
    req.add_header('Accept', '*/*')
    req.add_header('Charset', 'UTF-8')
    req.add_header('Connection', 'Keep-Alive')

    f = urlopen(req)
    # 跳过self.start_pos个字节，表明该线程只负责下载自己负责的那部分内容
    for i in range(self.start_pos):
      f.read(1)
    # 读取网络数据，并写入本地
    while self.length < self.current_part_size:
      data = f.read(1024)
      if data is None or len(data) <= 0:
        break
      self.current_part.write(data)
      # 累计该线程下载的总大小
      self.length += len(data)
    self.current_part.close()
    f.close()

#!/usr/bin/env python 
# -*- coding: utf-8 -*- 
# 文件名：thread_download-master.py

import sys
import time

from ThreadDownload import *


def show_process(dl):
  while dl.get_complete_rate() < 1:
    complete_rate = int(dl.get_complete_rate()*100) 
    print('\r' + '下载中···（已下载' + str(complete_rate) + '%）', end='', flush=True)
    time.sleep(0.01)


def main():
  try:  
    Link = input('[+]' + 'Link: ')
    file_path = input('[+]' + 'File Path: ')
    thread_number = input('[+]' + 'Thread Number: ')
    thread_number = int(thread_number)
    dl = Download(Link, file_path, thread_number)
    dl.download()
    print('\n开始下载!')
    show_process(dl)
    print('\r' + '下载中···（已下载' + '100%)', end='', flush=True)
    print('\n下载完成!')
  except Exception:
      print('Parameter Setting Error')
      sys.exit(1)

if __name__=='__main__':
    main()