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