@Conditional的用法

@Conditional进行条件判断： 符合条件则加载该bean，不符合则不加载该bean 示例

1、用于测试的bean实体

package com.bean;

/**
 * @auto dh
 * @create 2020-04-25-15:10
 */
public class Animal {
}

package com.bean;

/**
 * @auto dh
 * @create 2020-04-25-11:00
 */
public class Person {
}

2、实现condition的类

package com.condition;


import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;

/**
 * @auto dh
 * @create 2020-04-25-15:11
 */
public class Condition001 implements Condition {
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata annotatedTypeMetadata) {
//      context 代表Ioc容器  context.getBeanFactory 从Ioc容器里获取容器工厂  
//　　　　调用该容器工厂，判断是否包含该bean名为animal
        if(context.getBeanFactory().containsBean("animal")){
            return true;
        }
        return false;
    }
}

3、配置类

package com.configuration;

import com.bean.Animal;
import com.bean.Person;
import com.condition.Condition001;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;

/**
 * @auto dh
 * @create 2020-04-25-15:15
 */
@Configuration
public class ConditionTest001 {
//    @Bean
    public Animal animal() {
        return new Animal();
    }

    @Bean
//    如果Condition001.class返回true,则加载该bean,
//        否则不加载该bean
    @Conditional(Condition001.class)
    public Person person() {
        return new Person();
    }

}
4、测试类

package com.test;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

/**
 * @auto dh
 * @create 2020-04-25-15:16
 */
public class ConditionTest001 {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx=new AnnotationConfigApplicationContext(com.configuration.ConditionTest001.class);
        String[] beans=ctx.getBeanDefinitionNames();
        for(String str:beans){
            System.out.println("bean信息："+str);
        }
    }
}