django提供文件下載時，若果文件較小，解決辦法是先將要傳送的內容全生成在內存中，然后再一次性傳入Response對象中：
def simple_file_download(request): # do something... content = open("simplefile", "rb").read() return HttPResponse(content)如果文件非常大時，最簡單的辦法就是使用靜態文件服務器，比如Apache或者Nginx服務器來處理下載。不過有時候，我們需要對用戶的權限做一下限定，或者不想向用戶暴露文件的真實地址，或者這個大內容是臨時生成的(比如臨時將多個文件合并而成的)，這時就不能使用靜態文件服務器了。
django文檔中提到，可以向HttpResponse傳遞一個迭代器，流式的向客戶端傳遞數據。
要自己寫迭代器的話，可以用yield：
def read_file(filename, buf_size=8192): with open(filename, "rb") as f: while True: content = f.read(buf_size) if content: yield content else: breakdef big_file_download(request): filename = "filename" response = HttpResponse(read_file(filename)) return response
或者使用生成器表達式，下面是django文檔中提供csv大文件下載的例子：
import csvfrom django.utils.six.moves import rangefrom django.http import StreamingHttpResponseclass Echo(object): """An object that implements just the write method of the file-like interface. """ def write(self, value): """Write the value by returning it, instead of storing in a buffer.""" return valuedef some_streaming_csv_view(request): """A view that streams a large CSV file.""" # Generate a sequence of rows. The range is based on the maximum number of # rows that can be handled by a single sheet in most spreadsheet # applications. rows = (["Row {0}".format(idx), str(idx)] for idx in range(65536)) pseudo_buffer = Echo() writer = csv.writer(pseudo_buffer) response = StreamingHttpResponse((writer.writerow(row) for row in rows), content_type="text/csv") response['Content-Disposition'] = 'attachment; filename="somefilename.csv"' return response
python也提供一個文件包裝器，將類文件對象包裝成一個迭代器：
class FileWrapper: """Wrapper to convert file-like objects to iterables""" def __init__(self, filelike, blksize=8192): self.filelike = filelike self.blksize = blksize if hasattr(filelike,'close'): self.close = filelike.close def __getitem__(self,key): data = self.filelike.read(self.blksize) if data: return data raise IndexError def __iter__(self): return self def next(self): data = self.filelike.read(self.blksize) if data: return data raise StopIteration
使用時：
from django.core.servers.basehttp import FileWrapperfrom django.http import HttpResponseimport osdef file_download(request,filename): wrapper = FileWrapper(file('filepath')) response = HttpResponse(wrapper, content_type='application/octet-stream') response['Content-Length'] = os.path.getsize(path) response['Content-Disposition'] = 'attachment; filename=%s' % filename return responsedjango也提供了StreamingHttpResponse類來代替HttpResponse對流數據進行處理。
壓縮為zip文件下載：
import os, tempfile, zipfile from django.http import HttpResponse from django.core.servers.basehttp import FileWrapper def send_zipfile(request): """ Create a ZIP file on disk and transmit it in chunks of 8KB, without loading the whole file into memory. A similar approach can be used for large dynamic PDF files. """ temp = tempfile.TemporaryFile() archive = zipfile.ZipFile(temp, 'w', zipfile.ZIP_DEFLATED) for index in range(10): filename = __file__ # Select your files here. archive.write(filename, 'file%d.txt' % index) archive.close() wrapper = FileWrapper(temp) response = HttpResponse(wrapper, content_type='application/zip') response['Content-Disposition'] = 'attachment; filename=test.zip' response['Content-Length'] = temp.tell() temp.seek(0) return response
不過不管怎么樣，使用django來處理大文件下載都不是一個很好的注意，最好的辦法是django做權限判斷，然后讓靜態服務器處理下載。
這需要使用sendfile的機制："傳統的Web服務器在處理文件下載的時候，總是先讀入文件內容到應用程序內存，然后再把內存當中的內容發送給客戶端瀏覽器。這種方式在應付當今大負載網站會消耗更多的服務器資源。sendfile是現代操作系統支持的一種高性能網絡IO方式，操作系統內核的sendfile調用可以將文件內容直接推送到網卡的buffer當中，從而避免了Web服務器讀寫文件的開銷，實現了“零拷貝”模式。 "
Apache服務器里需要mod_xsendfile模塊來實現，而Nginx是通過稱為X-Accel-Redirect的特性來實現。
nginx配置文件：
# Will serve /var/www/files/myfile.tar.gz# When passed URI /protected_files/myfile.tar.gzlocation /protected_files { internal; alias /var/www/files;}或者
# Will serve /var/www/protected_files/myfile.tar.gz# When passed URI /protected_files/myfile.tar.gzlocation /protected_files { internal; root /var/www;}注意alias和root的區別。
django中：
response['X-Accel-Redirect']='/protected_files/%s'%filename
這樣當向django view函數發起request時，django負責對用戶權限進行判斷或者做些其它事情，然后向nginx轉發url為/protected_files/filename的請求，nginx服務器負責文件/var/www/protected_files/filename的下載：
@login_requireddef document_view(request, document_id): book = Book.objects.get(id=document_id) response = HttpResponse() name=book.myBook.name.split('/')[-1] response['Content_Type']='application/octet-stream' response["Content-Disposition"] = "attachment; filename={0}".format( name.encode('utf-8')) response['Content-Length'] = os.path.getsize(book.myBook.path) response['X-Accel-Redirect'] = "/protected/{0}".format(book.myBook.name) return response
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