Python ftplib使用问题：子目录文件下载与Zip文件解码错误

问题1：下载FTP子目录中的文件 #

有两种简单的实现方式：

方法1：先切换到目标子目录 #

使用ftp_server.cwd()方法切换到目标子目录，再执行下载操作：

import ftplib

HOSTNAME = "xxx"
USERNAME = "xxx"
PASSWORD = "xxx"

ftp_server = ftplib.FTP(HOSTNAME, USERNAME, PASSWORD)
ftp_server.encoding = "utf-8"

# 切换到指定子目录，示例路径为"docs/subfolder"
ftp_server.cwd("docs/subfolder")

filename = "gfg.txt"
with open(filename, "wb") as file:
    ftp_server.retrbinary(f"RETR {filename}", file.write)

ftp_server.dir()
ftp_server.quit()

方法2：直接指定文件完整路径 #

无需切换目录，直接在RETR命令中传入文件的完整路径：

import ftplib

HOSTNAME = "xxx"
USERNAME = "xxx"
PASSWORD = "xxx"

ftp_server = ftplib.FTP(HOSTNAME, USERNAME, PASSWORD)
ftp_server.encoding = "utf-8"

# 直接指定子目录下的文件完整路径
file_path = "docs/subfolder/gfg.txt"
# 提取文件名用于本地保存
filename = file_path.split("/")[-1]

with open(filename, "wb") as file:
    ftp_server.retrbinary(f"RETR {file_path}", file.write)

ftp_server.dir()
ftp_server.quit()

问题2：下载Zip文件时出现UnicodeDecodeError #

错误根源是你用**文本模式（"r"）**尝试读取二进制格式的Zip文件。Zip属于二进制文件，不能用文本编码解析。

修改方案（去掉无效的文本读取逻辑） #

import ftplib

HOSTNAME = "xxx"
USERNAME = "xxx"
PASSWORD = "xxx"

ftp_server = ftplib.FTP(HOSTNAME, USERNAME, PASSWORD)
ftp_server.encoding = "utf-8"

filename = "archive.zip"

with open(filename, "wb") as file:
    ftp_server.retrbinary(f"RETR {filename}", file.write)

ftp_server.dir()
ftp_server.quit()

如果需要解压Zip文件的示例 #

import ftplib
import zipfile

HOSTNAME = "xxx"
USERNAME = "xxx"
PASSWORD = "xxx"

ftp_server = ftplib.FTP(HOSTNAME, USERNAME, PASSWORD)
ftp_server.encoding = "utf-8"

filename = "archive.zip"

with open(filename, "wb") as file:
    ftp_server.retrbinary(f"RETR {filename}", file.write)

# 解压到指定目录
with zipfile.ZipFile(filename, 'r') as zip_ref:
    zip_ref.extractall("extracted_files")

ftp_server.dir()
ftp_server.quit()

内容的提问来源于stack exchange，提问作者alex1290