python django下载大的csv文件实现方法分析

def outputCSV(rows, fname="output.csv", headers=None):
  def getContent(fileObj):
    fileObj.seek(0)
    data = fileObj.read()
    fileObj.seek(0)
    fileObj.truncate()
    return data
  def genCSV(rows, headers):
    # 准备输出
    output = cStringIO.StringIO()
    # 写BOM
    output.write(bytearray([0xFF, 0xFE]))
    if headers != None and isinstance(headers, list):
      headers = codecs.encode("\t".join(headers) + "\n", "utf-16le")
      output.write(headers)
      yield getContent(output)
    for row in rows:
      rowData = codecs.encode("\t".join(row) + "\n", "utf-16le")
      output.write(rowData)
      yield getContent(output) #因为StreamingHttpResponse需要一个Iterator
    output.close()
  resp = StreamingHttpResponse(genCSV(rows, headers))
  resp["Content-Type"] = "application/vnd.ms-excel; charset=utf-16le"
  resp["Content-Type"] = "application/octet-stream"
  resp["Content-Disposition"] = "attachment;filename=" + fname
  resp["Content-Transfer-Encoding"] = "binary"
  return resp

headers = ["col1", "col2", ..., "coln"]
def genRows():
      for obj in objList:
        yield [obj.col1, obj.col2, ...obj.coln]   
#这样调用,返回response
return outputCSV(genRows(), "file.csv", headers)