完成一个文本聊天室程序的设计 I.能识别各自身份，可具有单独一对一聊天的功能 II.能保留历史记录，能设置好友，只与好友聊天 -Complete the design of a text chat program I. to identify their own identity, separate one-on-one chat function II able to preserve the historical record, can set up a friend,