Django的视图响应机制-一次性响应OR流式响应

一次性响应：HttpResponse类及其子类、JsonResponse类

流式响应：SteamingHttpResponse类、FileResponse类

文件下载为例

#HttpResponse方式，文件内容一次性响应，仅适合小文件
def file_download(request):
    with open('data.txt') as f:
        c=f.read()
    return HttpResponse(c)

#StreamingHttpResponse方式
def big_file_download(request):
    def file_iterator(file_name,chunk_size=512):
        with open(file_name) as f:
            while True:
                c=f.read(chunk_size)
                if c:
                    yield c
                else:
                    break
    fname="data.txt"
    response=StreamingHttpResponse(file_iterator(fname))
    return response

#FileResponse方式
#FileResponse是StreamingHttpResponse的子类，自动分段、自动迭代、适合二进制文件传输
def homeproc2(request):
    cwd=os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    response=FileResponse(open(cwd + "/msgapp/templates/PyLogo.jpg","rb"))
    #指定文件类型
    response['Content-type']='application/octet-stream'
    #指定文件名称
    response['Content-Disposition']='attachment;filename="pylogo.jpg'
    return response