通过调用它提供的一些方法，实现连接FTP服务器，上传/下载文件，目录操作等基本功能，便能开发出容易上手，效率较高的FTP客户端应用程序。-By calling it provides a number of ways to connect FTP server, upload/download files, directories, operations and other basic functions, will be able to develop easy to use, efficie