使用字典来保存其聊天用户、以及用链表来保存聊天记录；聊天界面中设有滚动条，其当页面每刷新滚动条总至底（自动滚动到最底部），望对你有所帮助-Use a dictionary to save their chat users, as well as a linked list to save chat history chat screen scroll bars, the scroll bar when the page is refreshed each total to the bottom