@Service注解

古城微笑少年丶 2023-07-17 15:40 4阅读 0赞

package org.springframework.stereotype;
    
    import java.lang.annotation.Documented;
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /** * Indicates that an annotated class is a "Service", originally defined by Domain-Driven * Design (Evans, 2003) as "an operation offered as an interface that stands alone in the * model, with no encapsulated state." * * <p>May also indicate that a class is a "Business Service Facade" (in the Core J2EE * patterns sense), or something similar. This annotation is a general-purpose stereotype * and individual teams may narrow their semantics and use as appropriate. * * <p>This annotation serves as a specialization of {@link Component @Component}, * allowing for implementation classes to be autodetected through classpath scanning. * * @author Juergen Hoeller * @since 2.5 * @see Component * @see Repository */
    @Target({ ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Component
    public @interface Service { 
    
    	/** * The value may indicate a suggestion for a logical component name, * to be turned into a Spring bean in case of an autodetected component. * @return the suggested component name, if any */
    	String value() default "";
    
    }

`@Service`注解：

*  在类上 使用该注解，表示其是一个`Service`
 *  最初由领域驱动设计（`Domain-Driven Design（Evans，2003）`)定义为“作为接口提供的操作，该操作在模型中独立存在，没有封装状态
 *  可能还表明某个类是“业务服务门面”（就核心J2EE模式而言），或类似的内容
 *  该注解是`@Component`注解的一个专业化的注解
 *  允许通过类路径扫描自动检测实现类

默认方法`value()`：

*  返回值类型是`String`类型
 *  无参数，`value`默认值是空
 *  该值可能表示对逻辑组件名称的建议  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI5MzQzMjU_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI5MzQzMjU_size_16_color_FFFFFF_t_70]: /images/20230528/4f623cf097734ef09505902c56f422d8.png