spring常用注解-@Value

@value将外部的值动态注入到Bean中

Bird

public class Bird {
    
    @Value("bider") //，注入普通字符串
    private String name;
    @Value("#{20-2}")//SpringEL 表达式
    private Integer age;
    @Value("${bird.color}")//读取配置文件
    private String color;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public String getColor() {
        return color;
    }
    public void setColor(String color) {
        this.color = color;
    }
    
    @Override
    public String toString() {
        return "Bird [name=" + name + ", age=" + age + ", color=" + color + "]";
    }
}

配置类

@Configuration
@PropertySource("classpath:bootstrap.properties")
public class MainConfig {
    
    @Bean
    public Bird Bird() {
        return new Bird();
    }
    

}

测试类

public class TestMain {

    

    public static void main(String[] args) {
        
        AnnotationConfigApplicationContext anno = new AnnotationConfigApplicationContext(MainConfig.class);
        
        for (String string : anno.getBeanDefinitionNames()) {
            System.out.println(string);
        }
                
        System.out.println("容器加载完成");
        
        Bird bird = (Bird) anno.getBean("Bird");
        System.out.println(bird.toString());
        //关闭容器
        anno.close();
        
        
    }
}

运行结果

:49:56.563 [main] DEBUG org.springframework.core.env.PropertySourcesPropertyResolver - Could not find key 'spring.liveBeansView.mbeanDomain' in any property source
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalRequiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
mainConfig
Bird
容器加载完成
21:49:56.566 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'Bird'
Bird [name=bider, age=18, color=red]
21:49:56.566 [main] INFO org.springframework.context.annotation.AnnotationConfigApplicationContext - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@6ea6d14e: startup date [Sun Sep 29 21:49:56 CST 2019]; root of context hierarchy
21:49:56.566 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'lifecycleProcessor'
21:49:56.566 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@2833cc44: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.event.internalEventListenerProcessor,org.springframework.context.event.internalEventListenerFactory,mainConfig,Bird]; root of factory hierarchy