方式一：读入内存后输出下载
此方式会耗费较大的内存，要服务器崩溃很容易。
def file_download(request):
downfilename = "filename.txt"
with open('filename.txt') as f:
c = f.read()
response = HttpResponse(c)
response['Content-Type'] = "application/octet-stream"
response['Content-Disposition'] = 'attachment;filename="%s.xlsx"' % (quote(downfilename))
return response
方式二：使用迭代器
block_size = 4096
downfilename = request.GET.get("filename", u"比赛排名").encode("utf-8")
filelike = file(file_full_path, "rb")
response = StreamingHttpResponse()
response.streaming_content = iter(lambda: filelike.read(block_size), '')
response['Content-Type'] = "application/octet-stream"
response['Content-Disposition'] = 'attachment;filename="%s.xlsx"' % (quote(downfilename))
方式三：yield，并使用with处理异常
downfilename = request.GET.get("filename", u"比赛排名").encode("utf-8")
def file_iterator(file_name, chunk_size=512):
with open(file_name, "rb") as f:
while True:
c = f.read(chunk_size)
if c:
yield c
else:
break
response = StreamingHttpResponse()
response.streaming_content = file_iterator(file_full_path)
response['Content-Type'] = "application/octet-stream"
response['Content-Disposition'] = 'attachment;filename="%s.xlsx"' % (quote(downfilename))
return response
注意使用rb方式打开，否则你的Excel将打不开。