使用@Value注解对bean进行属性注入

import org.springframework.beans.factory.annotation.Value;

public class Bottle {

    //使用字面量注入属性
    @Value(value = "red")
    private String color;

    //使用el表达式注入属性
    @Value(value = "#{30 / 3.14}")
    private double diameter;

    //使用占位符注入属性，需要在容器中引入配置文件
    @Value(value = "${bottle.source}")
    private String source;

    ……
    
}

/**
 * 配置类，使用@Value注解进行属性注入
 * 引入配置文件
 */
@Configuration
@PropertySource(value = {"classpath:/config.properties"})
public class BeanConfig {

    //使用无参构造器注册Bottle
    @Bean(value = "bottle")
    @Scope("singleton")
    public Bottle bottle() {
        return new Bottle();
    }
}

    @Test
    public void test() {
        //创建容器
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(ValueBeanConfig.class);
        //从容器中获取Bottle实例
        Bottle bottle = (Bottle) applicationContext.getBean("bottle");
        //控制台输出
        System.out.println(bottle.toString());
        //关闭容器
        ((AnnotationConfigApplicationContext)applicationContext).registerShutdownHook();
    }

bottle.source=laboratory
bottle.size=1599
bottle.nickname=frankie

//创建容器
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(ValueBeanConfig.class);
//从容器中获取环境变量
Environment environment = applicationContext.getEnvironment();
String source = environment.getProperty("bottle.source");