httpx 监视下载进度

如果需要监视大型响应的下载进度，可以使用响应流式处理并检查​response.num_bytes_downloaded​属性。

正确确定下载进度需要此接口，因为如果使用 HTTP 响应压缩，则返回的总字节数​response.content​或​response.iter_content()​并不总是与响应的原始内容长度相对应。

 注：下文的tqdm库和rich库都要使用pip进行安装，可以使用 ​pip install tqdm​ 来安装tqdm库，使用​ pip install rich​ 来安装rich库

例如，在下载响应时使用tqdm库显示进度条可以像这样完成...

import tempfile

import httpx
from tqdm import tqdm

with tempfile.NamedTemporaryFile() as download_file:
    url = "https://speed.hetzner.de/100MB.bin"
    with httpx.stream("GET", url) as response:
        total = int(response.headers["Content-Length"])

        with tqdm(total=total, unit_scale=True, unit_divisor=1024, unit="B") as progress:
            num_bytes_downloaded = response.num_bytes_downloaded
            for chunk in response.iter_bytes():
                download_file.write(chunk)
                progress.update(response.num_bytes_downloaded - num_bytes_downloaded)
                num_bytes_downloaded = response.num_bytes_downloaded

或者另一个例子，这次使用rich库...

import tempfile
import httpx
import rich.progress

with tempfile.NamedTemporaryFile() as download_file:
    url = "https://speed.hetzner.de/100MB.bin"
    with httpx.stream("GET", url) as response:
        total = int(response.headers["Content-Length"])

        with rich.progress.Progress(
            "[progress.percentage]{task.percentage:>3.0f}%",
            rich.progress.BarColumn(bar_width=None),
            rich.progress.DownloadColumn(),
            rich.progress.TransferSpeedColumn(),
        ) as progress:
            download_task = progress.add_task("Download", total=total)
            for chunk in response.iter_bytes():
                download_file.write(chunk)
                progress.update(download_task, completed=response.num_bytes_downloaded)