Springboot自定义Conditional学习笔记

1. 编写Condition实现类

   public class OnSystemPropertyCondition  implements Condition {
         
         
       @Override
       public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
         
         
           Map<String, Object> attributes =
                   metadata.getAnnotationAttributes(ConditionalOnSystemProperty.class.getName());
           String propertyName = (String) attributes.get("name") ;
           String propertyValue = (String) attributes.get("value") ;
           String systemPropertyValue = System.getProperty(propertyName) ;
           return propertyValue.equalsIgnoreCase(systemPropertyValue);
       }
   }
   

2. 编写Conditional注解类

   @Documented
   @Retention(RetentionPolicy.RUNTIME)
   @Target({
         
          ElementType.TYPE, ElementType.METHOD })
   @Conditional(OnSystemPropertyCondition.class)
   public @interface ConditionalOnSystemProperty{
         
         
       // Java 系统属性名称
       String name() default "" ;
       // Java 系统属性值
       String value() default "" ;
   }
   

3. 业务代码添加Conditional注解

   @ConditionalOnSystemProperty(name = "user.name", value = "yichengjie")//条件装配
   public class HelloWorldAutoConfiguration {
         
         
   }