note:addon开发基础知识
a. 比较 addon simple 和addon advanced区别 addon simple 只有两个相关点，一个command ，一个operation，简单说就是提供命令，还有命令对应的操作，利用roo提供的工具类 完成对应操作。
b.Roo核心各部分关系
c.主要模块功能：
Support — The
org.springframework.roo.support module provides common utility classes used by all the core modules and add-ons. Some utility classes include Assert, FileCopyUtils, XmlUtils, StringUtils, FileUtils, etc. For example, if you want to copy the content of one file to the other file, you could use FileCopyUtils to do it for you. 工具类，所有的文件处理，字符处理的类
Metadata — The org.springframework.roo.metadata module provides a metadata service provider interface and implementation that includes dependency registration and caching.
存储 项目，类，方法的信息，以及依赖关系
File monitor — The org.springframework.roo.file.monitor module publishes events following detected file system changes (the default implementation uses auto-scaled disk polling).
文件系统监视器，监测磁盘文件变更，并把这些事件发布
File undo — The org.springframework.roo.file.undo module provides a file undo facility for use by the process manager.
当命令发生异常时起作用
Project — The org.springframework.roo.project module abstracts typical end-user project build systems like Apache Maven and Apache Ant.
项目构建
Process manager — The org.springframework.roo.process.manager module offers an ACID-like file system abstraction that includes disk rollback and process synchronization.
处理文件回滚，进程同步
Classpath — The org.springframework.roo.classpath module performs abstract syntax tree parsing and type binding of Java and AspectJ compilation units.
处理java文件，aj文件的语法树解析，还有绑定
