# 創建Download項目
django-admin startproject Download
# 創建down_app app
python manage.py startapp down_app

import os
from django.http import HttpResponse
from django.http import StreamingHttpResponse


def image_down(request):
    """
    下載圖片
    """
    img_name = request.GET.get("username") + ".png"  # 二維碼圖片名
    base_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))  # 項目根目錄
    file_path = os.path.join(base_dir, 'antirisk/CodeGenerate/image/code', img_name)  # 二維碼的絕對路徑

    if not os.path.isfile(file_path):  # 判斷下載文件是否存在
        return HttpResponse("Sorry but Not Found the File")

    def file_iterator(file_path, chunk_size=512):
        """
        文件生成器,防止文件過大，導致內存溢出
        :param file_path: 文件絕對路徑
        :param chunk_size: 塊大小
        :return: 生成器
        """
        with open(file_path, mode='rb') as f:
            while True:
                c = f.read(chunk_size)
                if c:
                    yield c
                else:
                    break

    try:
        # 設置響應頭
        # StreamingHttpResponse將文件內容進行流式傳輸，數據量大可以用這個方法
        response = StreamingHttpResponse(file_iterator(file_path))
        # 以流的形式下載文件,這樣可以實現任意格式的文件下載
        response['Content-Type'] = 'application/octet-stream'
        # Content-Disposition就是當用戶想把請求所得的內容存為一個文件的時候提供一個默認的文件名
        response['Content-Disposition'] = f'attachment;filename="1.png"'  # 文件名不可設置為中文
    except:
        return HttpResponse("Sorry but Not Found the File")

    return response

from django.contrib import admin
from django.urls import path, re_path
from down_app import views

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', views.index),
    re_path('download/)', views.image_down, name="download"),
]

!DOCTYPE html>
html lang="en">
head>
    meta charset="UTF-8">
    title>Title/title>
/head>
body>
a href="/download/" rel="external nofollow" >下載圖片/a>
/body>
/html>

# 運行項目
python manage.py runserver