Spring @Order注解详解

article/2025/11/10 17:33:47

注解@Order的作用是定义Spring容器加载Bean的顺序。

源码

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD, ElementType.FIELD})
@Documented
public @interface Order {/*** The order value.* <p>Default is {@link Ordered#LOWEST_PRECEDENCE}.* @see Ordered#getOrder()*/int value() default Ordered.LOWEST_PRECEDENCE;}

public interface Ordered {/*** Useful constant for the highest precedence value.* @see java.lang.Integer#MIN_VALUE*/int HIGHEST_PRECEDENCE = Integer.MIN_VALUE;/*** Useful constant for the lowest precedence value.* @see java.lang.Integer#MAX_VALUE*/int LOWEST_PRECEDENCE = Integer.MAX_VALUE;/*** Get the order value of this object.* <p>Higher values are interpreted as lower priority. As a consequence,* the object with the lowest value has the highest priority (somewhat* analogous to Servlet {@code load-on-startup} values).* <p>Same order values will result in arbitrary sort positions for the* affected objects.* @return the order value* @see #HIGHEST_PRECEDENCE* @see #LOWEST_PRECEDENCE*/int getOrder();}

通过源码解读，我们可以得到以下结论：

注解可以作用在类、方法、字段声明（包括枚举常量）
注解有一个int类型的参数，可以不传，默认是最低优先级
通过常量类的值我们可以推测参数值越小优先级越高；

案例

创建三个pojo类Cat1, Cat2, Cat3，使用@Component注解将其交给Spring容器自动加载，每个类分别加上@Order(1), @Order(2), @Order(3)注解。

@Component
@Order(1)
public class Cat1 {public Cat1() {System.out.println("Order:1");}
}@Component
@Order(2)
public class Cat2 {public Cat2() {System.out.println("Order:2");}
}@Component
@Order(3)
public class Cat3 {public Cat3() {System.out.println("Order:3");}
}