实现的是一个简单的日记本程序，主要运用JTree和设计模式中的观察者模式，该模式实现统计日志中的数字和字符，将其分开显示。还能随时打开关闭日志，甚至是删除。读者可以自己设置源码中存日志的路径。-To achieve a simple diary program, mainly in the use the JTree and design mode observer mode, the mode to achieve statistical log of numbers and characters, will be shown separately. Close the log can be opened at any time, or even deleted. Readers can set up their own source memory path of the log.