生成一段断点续传代码

断点续传（Resumable Upload）是一种在网络上传文件时常用的策略，当网络连接中断后，可以从上次断开的地方继续上传，而不是从头开始。这通常通过将大文件分割成小块，在服务器端保存进度信息来实现。下面是一个简单的Python示例，使用requests库模拟HTTP请求的断点续传功能：

import requests
from io import BytesIO
import os

# 文件路径和大小
file_path = 'path_to_your_file'
file_size = os.path.getsize(file_path)

# 每次上传的小块大小
chunk_size = 1024 * 1024  # 1MB

def upload_chunk(start, end):
    with open(file_path, 'rb') as file:
        file.seek(start)
        chunk = file.read(end - start)
    response = requests.put('http://your-server/upload', data=chunk, headers={'Range': f'bytes={start}-{end-1}'})
    return response.status_code

# 定义总块数和已上传的块索引
total_chunks = file_size // chunk_size + (file_size % chunk_size > 0)
uploaded_chunks = 0

while uploaded_chunks < total_chunks:
    try:
        # 开始位置
        start = uploaded_chunks * chunk_size
        # 如果文件剩余部分小于一块大小，则读取完整块
        if file_size - start < chunk_size:
            end = file_size
        else:
            end = start + chunk_size
        
        status_code = upload_chunk(start, end)
        
        if status_code == 200 or status_code == 206:  # 表示成功或部分成功
            uploaded_chunks += 1
        else:
            print(f"Upload failed with status code {status_code}")
            break

    except Exception as e:
        print(f"Error occurred: {e}")
        # 记录失败的位置并重新开始从那里继续
        os.system(f'touch {file_path}.upload_inprogress')
        start = os.path.getsize(file_path) - chunk_size
        continue

if uploaded_chunks == total_chunks:
    print("File upload completed successfully.")