python 如何使用requests下载文件

login_url = "http://xxxx/api/auth/login"
login_data = {"username":"test3","password":"123456"}
login_res = requests.post(url=login_url,data = login_data)
token = login_res.json()["data"]["token"]

batch_url = "http://xxxx/api/models/batch"
batch_data = {"ids":"[4]","version_number":"[309]"}
headers = {"Authorization":"bearer %s" % token}
batch_res = requests.get(url=batch_url,params=batch_data,headers=headers)

file_path = batch_res.json()['data']['file_path']
file_name = batch_res.json()['data']['file_name']
down_url = "http://xxxx/api/report/down"
down_data = {"type":2,
             "file_path":file_path,
             "file_name":file_name,
             "token":token
             }
down_res = requests.get(url=down_url,params=down_data)
with open(file_name,"wb") as code:
    code.write(down_res.content)

def downloadfile(url,filename=None):
  if(not filename):							#如果参数没有指定文件名
    filename=os.path.basename(url)			#取用url的尾巴为文件名
  leng=1
  while(leng==1):
    torrent=requests.get(url,headers=headers)
    leng=len(list(torrent.iter_content(1024)))  #下载区块数
    if(leng==1):								#如果是1 就是空文件 重新下载
      print(filename,'下载失败,重新下载')
      sleep(1)
    else:
      print(path,'下载完成')
  with open(filename,'wb') as f:				
    for chunk in torrent.iter_content(1024):	#防止文件过大，以1024为单位一段段写入
      f.write(chunk)