安排周期性任务
现代应用程序经常需要定期运行特定的任务。在本指南中,你将学习如何安排定期任务。
If you need a clustered scheduler use the Quartz extension. |
先决条件
完成这个指南,你需要:
-
大概15分钟
-
编辑器
-
JDK 17+ installed with
JAVA_HOME
configured appropriately -
Apache Maven 3.9.8
-
如果你愿意的话,还可以选择使用Quarkus CLI
-
如果你想构建原生可执行程序,可以选择安装Mandrel或者GraalVM,并正确配置(或者使用Docker在容器中进行构建)
应用结构
In this guide, we create a straightforward application accessible using HTTP to get the current value of a counter. This counter is periodically (every 10 seconds) incremented.
解决方案
我们建议您按照下一节的说明逐步创建应用程序。然而,您可以直接转到已完成的示例。
克隆 Git 仓库: git clone https://github.com/quarkusio/quarkus-quickstarts.git
,或下载一个 存档 。
The solution is located in the scheduler-quickstart
directory.
创建Maven项目
首先,我们需要一个新的工程项目。用以下命令创建一个新项目:
For Windows users:
-
If using cmd, (don’t use backward slash
\
and put everything on the same line) -
If using Powershell, wrap
-D
parameters in double quotes e.g."-DprojectArtifactId=scheduler-quickstart"
It generates a new project including:
-
a landing page accessible on
http://localhost:8080
-
example
Dockerfile
files for bothnative
andjvm
modes -
应用程序的配置文件
The project also imports the Quarkus REST (formerly RESTEasy Reactive) and scheduler extensions.
If you already have your Quarkus project configured, you can add the scheduler
extension
to your project by running the following command in your project base directory:
quarkus extension add scheduler
./mvnw quarkus:add-extension -Dextensions='scheduler'
./gradlew addExtension --extensions='scheduler'
这会将以下内容添加到你的构建文件中:
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-scheduler</artifactId>
</dependency>
implementation("io.quarkus:quarkus-scheduler")
创建一个计划作业
In the org.acme.scheduler
package, create the CounterBean
class, with the following content:
package org.acme.scheduler;
import java.util.concurrent.atomic.AtomicInteger;
import jakarta.enterprise.context.ApplicationScoped;
import io.quarkus.scheduler.Scheduled;
import io.quarkus.scheduler.ScheduledExecution;
@ApplicationScoped (1)
public class CounterBean {
private AtomicInteger counter = new AtomicInteger();
public int get() { (2)
return counter.get();
}
@Scheduled(every="10s") (3)
void increment() {
counter.incrementAndGet(); (4)
}
@Scheduled(cron="0 15 10 * * ?") (5)
void cronJob(ScheduledExecution execution) {
counter.incrementAndGet();
System.out.println(execution.getScheduledFireTime());
}
@Scheduled(cron = "{cron.expr}") (6)
void cronJobWithExpressionInConfig() {
counter.incrementAndGet();
System.out.println("Cron expression configured in application.properties");
}
}
1 | Declare the bean in the application scope |
2 | get() 方法允许检索当前值。 |
3 | Use the @Scheduled annotation to instruct Quarkus to run this method every 10 seconds provided a worker thread is available
(Quarkus is using 10 worker threads for the scheduler). If it is not available the method invocation should be re-scheduled by default i.e.
it should be invoked as soon as possible. The invocation of the scheduled method does not depend on the status or result of the previous invocation. |
4 | The code is pretty straightforward. Every 10 seconds, the counter is incremented. |
5 | Define a job with a cron-like expression. The annotated method is executed at 10:15am every day. |
6 | 在 application.properties 中使用类似于cron表达式的方式定义一个名为 cron.expr 的作业。 |
更新该应用程序的配置文件
Edit the application.properties
file and add the cron.expr
configuration:
# By default, the syntax used for cron expressions is based on Quartz - https://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/crontrigger.html
# You can change the syntax using the following property:
# quarkus.scheduler.cron-type=unix
cron.expr=*/5 * * * * ?
Creating the REST resource
Create the CountResource
class as follows:
package org.acme.scheduler;
import jakarta.inject.Inject;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;
@Path("/count")
public class CountResource {
@Inject
CounterBean counter; (1)
@GET
@Produces(MediaType.TEXT_PLAIN)
public String hello() {
return "count: " + counter.get(); (2)
}
}
1 | 注入 CounterBean |
2 | 返回当前计数器的值 |
打包并运行该应用程序
使用以下命令运行该应用程序:
quarkus dev
./mvnw quarkus:dev
./gradlew --console=plain quarkusDev
在另一个终端,运行 curl localhost:8080/count
检查计数器的值。几秒钟后,重新运行 curl localhost:8080/count
,以验证计数器已被递增。
Observe the console to verify that the message Cron expression configured in application.properties
has been displayed indicating
that the cron job using an expression configured in application.properties
has been triggered.
像往常一样,该应用程序能够使用以下方式进行打包:
quarkus build
./mvnw install
./gradlew build
And executed with java -jar target/quarkus-app/quarkus-run.jar
.
你也可以通过以下命令生成本地可执行文件:
quarkus build --native
./mvnw install -Dnative
./gradlew build -Dquarkus.native.enabled=true
Scheduler Configuration Reference
Configuration property fixed at build time - All other configuration properties are overridable at runtime
Configuration property |
类型 |
默认 |
---|---|---|
The syntax used in CRON expressions. Environment variable: Show more |
|
|
Scheduled task metrics will be enabled if a metrics extension is present and this value is true. Environment variable: Show more |
boolean |
|
Controls whether tracing is enabled. If set to true and the OpenTelemetry extension is present, tracing will be enabled, creating automatic Spans for each scheduled task. Environment variable: Show more |
boolean |
|
By default, only one Scheduler implementations will be started depending on the value of Environment variable: Show more |
boolean |
|
If schedulers are enabled. Environment variable: Show more |
boolean |
|
Scheduled task will be flagged as overdue if next execution time is exceeded by this period. Environment variable: Show more |
|
|
Scheduler can be started in different modes. By default, the scheduler is not started unless a Environment variable: Show more |
|
About the Duration format
To write duration values, use the standard You can also use a simplified format, starting with a number:
In other cases, the simplified format is translated to the
|