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responsereturn outputCSV(genRows(), "file.csv", headers)