spring @condition注解是用来在不同条件下注入不同实现的

demo如下:

package com.foreveross.service.weixin.test.condition;import org.springframework.context.annotation.Condition;import org.springframework.context.annotation.ConditionContext;import org.springframework.core.type.AnnotatedTypeMetadata;/** *  * windows下的环境 * */public class WindowsCondition implements Condition{    @Override    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {            return context.getEnvironment().getProperty("os.name").contains("Windows");    }    }

package com.foreveross.service.weixin.test.condition;import org.springframework.context.annotation.Condition;import org.springframework.context.annotation.ConditionContext;import org.springframework.core.type.AnnotatedTypeMetadata;public class LinuxCondition implements Condition{    @Override    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {                return context.getEnvironment().getProperty("os.name").contains("Linux");    }}

package com.foreveross.service.weixin.test.condition;public interface ListService {    String showListCmd();}

package com.foreveross.service.weixin.test.condition;import org.springframework.stereotype.Service;@Servicepublic class LinuxService implements ListService {    public String showListCmd(){        return "ls";    }    }

package com.foreveross.service.weixin.test.condition;import org.springframework.stereotype.Service;@Servicepublic class WindowsService implements ListService{    public String showListCmd(){        return "dir";    }    }

package com.foreveross.service.weixin.test.condition;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Conditional;import org.springframework.context.annotation.Configuration;@Configurationpublic class MyConfiguration {    @Bean(name = "service")    @Conditional(WindowsCondition.class)    public ListService windowsService() {        return new WindowsService();    }    @Bean(name = "service")    @Conditional(LinuxCondition.class)    public ListService linuxEmailerService() {        return new LinuxService();    }}

package com.foreveross.service.weixin.test.condition;import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class Test {    public static void main(String[] args) {                AnnotationConfigApplicationContext context=new AnnotationConfigApplicationContext(MyConfiguration.class);                ListService service= context.getBean(ListService.class);                System.out.println("操作符为:"+service.showListCmd()+",系统为:"+context.getEnvironment().getProperty("os.name"));                context.close();    }}