Spring---条件注解@Conditional

1、概述

　　　　1.1、Spring4  提供了一个更通用的  基于条件的Bean的创建，即使用@Conditional注解；

　　　　1.2、案例

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package com.an.config;   import com.an.conditon.WindowsCondition; import com.an.conditon.WindowsListService; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Conditional; import org.springframework.context.annotation.Configuration;   /**  * @description:  * @author: anpeiyong  * @date: Created in 2019/11/20 20:27  * @since:  */ @Configuration public class ConditionConfig {       @Bean     @Conditional(value = WindowsCondition.class)     WindowsListService listService(){         return new WindowsListService();     } }

　　

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package com.an.conditon;   import org.springframework.context.annotation.Condition; import org.springframework.context.annotation.ConditionContext; import org.springframework.core.type.AnnotatedTypeMetadata;   /**  * @description:  * @author: anpeiyong  * @date: Created in 2019/11/20 20:24  * @since:  */ public class WindowsCondition implements Condition {     @Override     public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {         return context.getEnvironment().getProperty("os.name").contains("Windows");     } }

　　

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package com.an.conditon;   /**  * @description:  * @author: anpeiyong  * @date: Created in 2019/11/20 20:26  * @since:  */ public class WindowsListService {       public String listCmd(){         return "dir";     } }

　　

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package com.an.main;   import com.an.conditon.WindowsListService; import com.an.config.ConditionConfig; import org.springframework.context.annotation.AnnotationConfigApplicationContext;   /**  * @description:  * @author: anpeiyong  * @date: Created in 2019/11/20 20:29  * @since:  */ public class ConditionMainTest {       public static void main(String[] args) {         AnnotationConfigApplicationContext annotationConfigApplicationContext=new AnnotationConfigApplicationContext(ConditionConfig.class);         WindowsListService windowsListService=annotationConfigApplicationContext.getBean(WindowsListService.class);         System.out.println(annotationConfigApplicationContext.getEnvironment().getProperty("os.name")+"该系统下的命令："+windowsListService.listCmd());     } }   结果： Windows 10该系统下的命令：dir