Spring3.0新特性（三）
3、常见三种配置方式：XML、Annotation、JavaConfig（spring3.0新增）
JavaConfig配置：

@Configurationpublic class AppConfig {@Beanpublic UserDAO userDAO() {return new UserDAOImpl();}@Beanpublic UserService userService() {UserServiceImpl service = new UserServiceImpl();service.setUserDAO(userDAO());return service;}}