Order注解启动顺序
order的规则
- order的值越小，优先级越高
- 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
- 该注解等同于实现Ordered接口getOrder方法，并返回数字。
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@Retention(RetentionPolicy.RUNTIME)@Target({ElementType.TYPE, ElementType.METHOD, ElementType.FIELD})@Documentedpublic @interface Order { /** * The order value. * <p>Default is {@link Ordered#LOWEST_PRECEDENCE}. * @see Ordered#getOrder() */ int value() default Ordered.LOWEST_PRECEDENCE; } |
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int LOWEST_PRECEDENCE = Integer.MAX_VALUE; |
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@Aspect@Componentpublic class DataSourceAspect implements Ordered { @Override public int getOrder() { return 1; } } |
见下
OrderRunner1.java
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@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
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@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
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@Componentpublic class Runner implements CommandLineRunner { @Override public void run(String... args) throws Exception { System.out.println("The Runner start to initialize ..."); }}@SpringBootApplicationpublic 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
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The service to start.......The OrderRunner1 start to initialize ...The OrderRunner2 start to initialize ...The Runner start to initialize ...The service has started. |
@Order注解提供消费顺序
Order注解可以做到集合bean依赖注入的时候，定义集合内部Bean的加载顺序，因此在需要有序消费bean的时候，不需要再次排序，直接定义好Order注解得value值就好。
但是这个order值并不影响bean本身实例化的顺序，因为实例化的顺序取决于依赖关系。
@org.springframework.core.annotation.Order
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@RestController@RequestMapping(value = "/pc/api/v1/monitor")@RequiredArgsConstructorpublic class AfterRepairConsumer { private final List<RepairCreatePostConsumer> postConsumers; @GetMapping(value = "/create") public ResponseData create() { final String repairId = "1"; if (CollectionUtils.isNotEmpty(postConsumers)) { postConsumers.forEach(e -> e.postHandler(repairId)); } return new ResponseData<>("success"); } } public interface RepairCreatePostConsumer { /** * 创建报修单后做什么 * * @param repairId 报修单ID */ void postHandler(String repairId);} import org.springframework.core.annotation.Order; @Service@RequiredArgsConstructor@Order(value = 3)public class SendEmail implements RepairCreatePostConsumer { @Override public void postHandler(String repairId) { System.out.println("为报修单" + repairId + "发送邮件"); }} import org.springframework.core.annotation.Order; @Service@RequiredArgsConstructor@Order(value = 2)public class SendInvoice implements RepairCreatePostConsumer { @Override public void postHandler(String repairId) { System.out.println("为报修单" + repairId + "发送发票"); }} import org.springframework.core.annotation.Order; @Service@RequiredArgsConstructor@Order(value = 1)public class SendMessage implements RepairCreatePostConsumer { @Override public void postHandler(String repairId) { System.out.println("为报修单" + repairId + "发送消息"); }} |
运行结果：
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/jiangxwa/article/details/87892577
