客户机上传下载功能 可以输入用户名，密码，得到验证-From the client can download function to enter a user name, password, be verified

实现交互式FTP 客户端，在提示下各输入IP，用户名，密码和所传的文件-To achieve interactive FTP client, all at the prompt enter the IP, user name, password and the file transfer