spring注解第03課 按條件加載Bean @Conditional

package com.atguigu.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;

import com.atguigu.bean.Person;
import com.atguigu.condition.LinuxCondition;
import com.atguigu.condition.WindowsCondition;
import com.atguigu.test.IOCTest;

//類中組件統一設置。滿足當前條件，這個類中配置的所有bean注冊都能生效；
@Conditional({WindowsCondition.class})
@Configuration
public class MainConfig2 {
    /**
     * @Conditional({Condition}) ： 按照一定的條件進行判斷，滿足條件給容器中注冊bean
     * 
     * 如果系統是windows，給容器中注冊("bill")
     * 如果是linux系統，給容器中注冊("linus")
     */
    @Conditional({WindowsCondition.class})
    @Bean("bill")
    public Person person01(){
        return new Person("Bill Gates",62);
    }
    
    @Conditional(LinuxCondition.class)
    @Bean("linus")
    public Person person02(){
        return new Person("linus", 48);
    }
}

2.條件1

package com.atguigu.condition;

import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotatedTypeMetadata;

//判斷是否linux系統
public class LinuxCondition implements Condition {

    /**
     * ConditionContext：判斷條件能使用的上下文（環境）
     * AnnotatedTypeMetadata：注釋信息
     */
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        // TODO是否linux系統
        //1、能獲取到ioc使用的beanfactory
        ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
        //2、獲取類加載器
        ClassLoader classLoader = context.getClassLoader();
        //3、獲取當前環境信息
        Environment environment = context.getEnvironment();
        //4、獲取到bean定義的注冊類
        BeanDefinitionRegistry registry = context.getRegistry();
        
        String property = environment.getProperty("os.name");
        
        //可以判斷容器中的bean注冊情況，也可以給容器中注冊bean
        boolean definition = registry.containsBeanDefinition("person");
        if(property.contains("linux")){
            return true;
        }
        
        return false;
    }

}

 

3.條件2

package com.atguigu.condition;

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

//判斷是否windows系統
public class WindowsCondition implements Condition {

    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        Environment environment = context.getEnvironment();
        String property = environment.getProperty("os.name");
        if(property.contains("Windows")){
            return true;
        }
        return false;
    }

}