python多线程下载文件合并

Python中使用多线程下载文件并合并，通常可以利用`concurrent.futures`模块，它提供了一个高级API来异步执行函数。下面是一个简单的示例，展示如何创建一个线程池来并发下载文件，然后将它们合并：

import concurrent.futures
import requests
import os

def download_file(url, filename):
    response = requests.get(url, stream=True)
    with open(filename, 'wb') as f:
        for chunk in response.iter_content(chunk_size=1024): 
            if chunk: # filter out keep-alive new chunks
                f.write(chunk)

# 指定要下载的URL列表和目标文件夹
urls = ['http://example.com/file1', 'http://example.com/file2', 'http://example.com/file3']
target_folder = 'downloaded_files'

with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
    future_to_url = {executor.submit(download_file, url, os.path.join(target_folder, os.path.basename(url))): url for url in urls}
    for future in concurrent.futures.as_completed(future_to_url):
        url = future_to_url[future]
        try:
            future.result()  # 等待任务完成
        except Exception as exc:
            print(f"Failed to download {url}: {exc}")

# 合并文件（这里假设所有文件都是二进制流，如果需要文本内容合并，操作会更复杂）
# 这一步通常是在所有文件都下载完成后，通过追加的方式将内容合并到一个大文件中
# merge_files(os.path.join(target_folder, '*.txt'), 'merged.txt')