python，Pyqt5 实现FTP服务器与客户端文件上传，下载

PyQt5是一个Python绑定的Qt库，可以用来创建GUI应用程序。要实现FTP服务器与客户端文件上传和下载功能，你可以使用Python内置的ftplib库来处理FTP操作。

首先，你需要创建一个FTP服务器。可以使用Python的ftplib库来实现这一点。下面是一个简单的例子：

from ftplib import FTP

def start_ftp_server():
    ftp = FTP()
    ftp.set_pasv(True)
    ftp.bind(("localhost", 21))
    ftp.listen(5)
    
    while True:
        conn, addr = ftp.accept()
        print("Connected by", addr)
        
        conn.send("220 Welcome to the FTP server\r\n")
        
        while True:
            command = conn.recv(1024).decode().strip()
            
            if command == "QUIT":
                conn.send("221 Goodbye\r\n")
                conn.close()
                break
                
            elif command.startswith("STOR"):
                filename = command.split(" ")[1]
                conn.send("150 Ok to send data\r\n")
                with open(filename, "wb") as file:
                    while True:
                        data = conn.recv(1024)
                        if not data:
                            break
                        file.write(data)
                conn.send("226 Transfer complete\r\n")
                
            elif command.startswith("RETR"):
                filename = command.split(" ")[1]
                try:
                    file = open(filename, "rb")
                    conn.send("150 Ok to send data\r\n")
                    data = file.read(1024)
                    while data:
                        conn.send(data)
                        data = file.read(1024)
                    file.close()
                    conn.send("226 Transfer complete\r\n")
                except FileNotFoundError:
                    conn.send("550 File not found\r\n")
                    
            else:
                conn.send("500 Unknown command\r\n")

start_ftp_server()

上述代码创建了一个简单的FTP服务器，监听本地地址的21端口。它支持QUIT、STOR和RETR命令。QUIT命令用于断开连接，STOR命令用于上传文件，RETR命令用于下载文件。

接下来，你可以使用PyQt5创建一个FTP客户端的GUI应用程序。下面是一个示例：

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QFileDialog, QMessageBox
from PyQt5.uic import loadUi
from ftplib import FTP

class FTPClient(QMainWindow):
    def __init__(self):
        super(FTPClient, self).__init__()
        loadUi("ftp_client.ui", self)  # 使用Qt Designer设计的UI文件
        
        self.connectButton.clicked.connect(self.connect_to_server)
        self.uploadButton.clicked.connect(self.upload_file)
        self.downloadButton.clicked.connect(self.download_file)
        
        self.ftp = FTP()
        
    def connect_to_server(self):
        host = self.hostLineEdit.text()
        port = int(self.portLineEdit.text())
        username = self.usernameLineEdit.text()
        password = self.passwordLineEdit.text()
        
        try:
            self.ftp.connect(host, port)
            self.ftp.login(username, password)
            self.statusbar.showMessage("Connected to FTP server")
        except Exception as e:
            self.statusbar.showMessage("Failed to connect: " + str(e))
            
    def upload_file(self):
        file_path, _ = QFileDialog.getOpenFileName(self, "Select file to upload")
        if file_path:
            try:
                with open(file_path, "rb") as file:
                    self.ftp.storbinary("STOR " + file_path, file)
                self.statusbar.showMessage("File uploaded successfully")
            except Exception as e:
                self.statusbar.showMessage("Failed to upload file: " + str(e))
                
    def download_file(self):
        file_path, _ = QFileDialog.getSaveFileName(self, "Save file as")
        if file_path:
            try:
                with open(file_path, "wb") as file:
                    self.ftp.retrbinary("RETR " + file_path, file.write)
                self.statusbar.showMessage("File downloaded successfully")
            except Exception as e:
                self.statusbar.showMessage("Failed to download file: " + str(e))
                
if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = FTPClient()
    window.show()
    sys.exit(app.exec_())

上述代码使用PyQt5创建了一个简单的FTP客户端应用程序。它连接到指定的FTP服务器，并提供了上传和下载文件的功能。

你需要使用Qt Designer设计一个UI界面，并保存为ftp_client.ui文件。然后，使用`loadUi`函数加载UI文件。

这只是一个简单的示例，你可以根据自己的需求进行修改和扩展。希望对你有所帮助！