方式一：使用HttpResponse
路由url：
    url(r'^download/',views.download,name="download"),
views.py代码
    from django.shortcuts import HttpResponse
    def download(request):
       file = open('crm/models.py', 'rb')
       response = HttpResponse(file)
       response['Content-Type'] = 'application/octet-stream' #设置头信息，告诉浏览器这是个文件
       response['Content-Disposition'] = 'attachment;filename="models.py"'
       return response

    方式二：使用StreamingHttpResponse, 其他逻辑不变，主要变化在后端处理:
      from django.http import StreamingHttpResponse
      def download(request):
         file=open('crm/models.py','rb')
         response =StreamingHttpResponse(file)
         response['Content-Type']='application/octet-stream'
         response['Content-Disposition']='attachment;filename="models.py"'
         return response

方式三：使用FileResponse
from django.http import FileResponse
def download(request):
 file=open('crm/models.py','rb')
 response =FileResponse(file)
 response['Content-Type']='application/octet-stream'
 response['Content-Disposition']='attachment;filename="models.py"'
 return response