SpringBoot之Order注解启动顺序

order的规则：

1. order的值越小，优先级越高
2. order如果不标注数字，默认最低优先级，因为其默认值是int最大值
3. 该注解等同于实现Ordered接口getOrder方法，并返回数字。

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD, ElementType.FIELD})
@Documented
public @interface Order {

	/**
	 * The order value.
	 * 
Default is {@link Ordered#LOWEST_PRECEDENCE}.
	 * @see Ordered#getOrder()
	 */
	int value() default Ordered.LOWEST_PRECEDENCE;

}

 

	int LOWEST_PRECEDENCE = Integer.MAX_VALUE;

@Aspect
@Component
public class DataSourceAspect implements Ordered {
   
    @Override
    public int getOrder() {
        return 1;
    }

}

见下： 

OrderRunner1.java

@Component
@Order(1)
public class OrderRunner1 implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        System.out.println("The OrderRunner1 start to initialize ...");
    }
}

 OrderRunner2.java

@Component
@Order(2)
public class OrderRunner2 implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        System.out.println("The OrderRunner2 start to initialize ...");
    }
}

 Runner.java

@Component
public class Runner implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        System.out.println("The Runner start to initialize ...");
    }
}

@SpringBootApplication
public class CommandLineRunnerApplication {

	public static void main(String[] args) {
		System.out.println("The service to start.");
		SpringApplication.run(CommandLineRunnerApplication.class, args);
		System.out.println("The service has started.");
	}
}

 

它们的启动日志：

The service to start.
...
...
The OrderRunner1 start to initialize ...
The OrderRunner2 start to initialize ...
The Runner start to initialize ...
The service has started.