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}) @Documented public @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 @Component public 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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@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
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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" ) @RequiredArgsConstructor public 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。
原文链接：https://blog.csdn.net/jiangxwa/article/details/87892577
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