@SpringBootApplication
声明让springboot进行自动配置，用于注解类
@SpringBootApplication=@Configuration+@EnableAutoConfiguration+@ComponentScan
@Configuration
声明项目的配置类
@EnableAutoConfiguration
用于自动配置
@ComponentScan
用于自动发现和装配bean
@Import
用来导入其他配置类
@ImportResource
用来加载xml配置文件
@ResponseBody
将返回结果写入HTTP response body，用于注解方法，一般在异步获取数据时使用，用于构建RESTful的api。不加@ResponseBody时，返回结果解析为路径跳转
@Controller
定义控制器，用于注解类，在spring 项目中由控制器负责将用户发来的URL请求转发到对应的服务接口（service层）
@RestController
用于标注控制层组件(如struts中的action)
@RestController=@ResponseBody+@Controller
@RequestMapping
提供路由信息，负责URL到Controller中的具体函数的映射
@Autowired和@Inject
两个注解都用来自动导入依赖的bean，只是@Inject注解没有required属性
@Compoent和@bean
@Component and its specializations (@Controller, @Service and @Repository) allow for auto-detection using classpath scanning.
| Annotation | Purpose | Annotation | Purpose |
|---|---|---|---|
| @Component | A candidate for auto-detection via classpath scanning. | @Component | A candidate for auto-detection via classpath scanning. |
| @Controller | A web controller, popularized by Spring MVC. | @Controller | A web controller, popularized by Spring MVC. |
| @Repository | Data manager / storage, ties to enterprise apps (DAO, DDD) | @Repository | Data manager / storage, ties to enterprise apps (DAO, DDD) |
| @Service | Meant to provide business logic – a (stateless) facade. | @Service | Meant to provide business logic – a (stateless) facade. |
@Bean on the other hand can only be used to explicitly declare a single bean in a configuration class.
@Qualifier
与@Autowired配合使用，当有多个同一类型的bean时，可以用@Qualifier(“name”)来指定。
