Spring @value和@PropertySource注解使用方法解析

public class Cat {
  @Value("猫") //直接注入字符串
  private String name;
  @Value("#{12+2}") //支持EL表达式
  private int age;
  @Value("${parent}") //支持配置文件读取
  private String parent;
  public Cat() {
    System.out.println("猫被初始化");
  }

  @Override
  public String toString() {
    return "Cat{" +
        "name='" + name + '\'' +
        ", age=" + age +
        ", parent='" + parent + '\'' +
        '}';
  }
}

@Import({Cat.class})
@PropertySources({@PropertySource(value ="cat.properties")})
public class Appconfig {
}

public class Demo {
  public static void main(String[] args) {

    AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Appconfig.class);
    Cat bean = context.getBean(Cat.class);
    System.out.println(bean); //Cat{name='猫', age=14, parent='tiger'}
    ConfigurableEnvironment environment = context.getEnvironment();
    System.out.println(environment.getProperty("parent")); //tiger


  }
}