【SpringBoot】15. Spring Boot核心注解

Spring Boot核心注解

1 @SpringBootApplication 代表是Spring Boot启动的类
2 @SpringBootConfiguration 通过bean对象来获取配置信息 (被@Configuration修饰所以才能够获取配置信息)
3 @Configuration 通过对bean对象的操作替代spring中的xml文件
4 @EnableAutoConfiguration 完成一些初始化环境的配置
5 @ComponentScan 完成spring的组件扫描。替代之前在xml文件中配置组件扫描的配置(context:component-scan pacage=”....”)
6 @RestController 1,表示一个 Controller。2,表示当前这个 Controller 下的所有的方法都会以 json 格式的数据响应。 和 @Controller + @ResponseBody组合使用一样。

1.@SpringBootApplication —— Spring Boot启动的类

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
		@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
		@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {

	@AliasFor(annotation = EnableAutoConfiguration.class, attribute = "exclude")
	Class<?>[] exclude() default {};

	@AliasFor(annotation = EnableAutoConfiguration.class, attribute = "excludeName")
	String[] excludeName() default {};

	@AliasFor(annotation = ComponentScan.class, attribute = "basePackages")
	String[] scanBasePackages() default {};

	@AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses")
	Class<?>[] scanBasePackageClasses() default {};

}

其中有3个注解是我们所关心的:

  1. @SpringBootConfiguration
  2. @EnableAutoConfiguration
  3. @ComponentScan

2.@SpringBootConfiguration —— 通过bean对象来获取配置信息

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Configuration
public @interface SpringBootConfiguration {

}

这个注解是空的,什么都没有,但是他被另一个注解所修饰——@Configuration

3.@Configuration —— 通过对bean对象的操作替代Spring中的xml文件

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Configuration {
	String value() default "";
}

4.@EnableAutoConfiguration —— 根据导入的jar包创建启动环境

@SuppressWarnings("deprecation")
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(EnableAutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {

	String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";

	/**
	 * Exclude specific auto-configuration classes such that they will never be applied.
	 * @return the classes to exclude
	 */
	Class<?>[] exclude() default {};

	/**
	 * Exclude specific auto-configuration class names such that they will never be
	 * applied.
	 * @return the class names to exclude
	 * @since 1.3.0
	 */
	String[] excludeName() default {};

}

5.@ComponentScan —— 完成spring的组件扫描

代替了xml文件中的:

<context:component-scan pacage=”....”></context:component-scan>

6.@RestController —— 一个Controller 且该controller下的所有数据以json格式的数据响应

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Controller
@ResponseBody
public @interface RestController {
	String value() default "";
}

他被@Controller 和 @ResponseBody 同时修饰 , 因此@RestController = @Controller + @ResponseBody

原文地址:https://www.cnblogs.com/isdxh/p/13529219.html