The technical principles of the vert.x cron framework in the Java library detailed explanation
The vert.x cron framework is a library for scheduling the task in the Vert.x application.It is based on the CRON expression and can help developers perform repetitive tasks in accordance with the specified timetable.This article will introduce the technical principles of the vert.x cron framework in the Java class library in detail, and provide relevant Java code examples.
1. 1. Background
Vert.x is a toolkit for building high -performance, responsive applications. It is a scalable asynchronous framework based on JVM.It provides many modules and tools to help developers build various types of applications.CRON is a time expression for performing tasks in a specific time interval.Combining CRON and Vert.x can easily implement the function of timing tasks in the vert.x application, such as sending emails regularly, regular cleaning databases, etc.
Second, the working principle of the Vert.x Cron framework
1. Introduce vert.x cron dependencies
To use the Vert.x Cron framework in the Java application, we first need to introduce the dependencies of Vert.x Cron in the project construction tool (such as Maven, Gradle).For example, you can add the following code to the pom.xml file of the project in Maven:
<dependency>
<groupId>io.vertx</groupId>
<artifactId>vertx-cron</artifactId>
<version>3.9.2</version>
</dependency>
2. Create CRON expression
CRON expression is a time expression for describing timing tasks.By specifying different time fields and passing, various types of duplicate tasks can be defined.The following is an example of a CRON expression:
"0 0 12 * * ?"
The above expression indicates the task of performing the task at 12 noon every day.
3. Create an vert.x cron instance
In the Java code, you need to create a Vert.x Cron instance and specify the task that needs to be executed and the time expression of trigger tasks.You can use the method of `cronexpression.create ()` to create a cron instance, and use the `cron.register () method to register the task.
The following is an example code:
import io.vertx.cron.CronEvent;
import io.vertx.cron.CronExpression;
import io.vertx.core.AbstractVerticle;
import io.vertx.core.Future;
import io.vertx.core.Vertx;
public class MyCronVerticle extends AbstractVerticle {
@Override
public void start(Future<Void> startFuture) {
Vertx vertx = getVertx();
CronExpression cronExpression = CronExpression.create("0 0 12 * * ?");
CronEvent cronEvent = CronEvent.create(cronExpression, event -> {
// The logical code of executing the task
System.out.println ("Perform Time Mission");
});
Cron cron = Cron.create(vertx);
cron.register(cronEvent);
startFuture.complete();
}
}
In the above example code, we created a cron instance `cron`, and registered a task called` Cronevent`.The task executes a simple code when the specified time expression triggered.
4. Deploy verticle
Finally, in the main class of the application, we need to deploy the Vert.x Cron Verticle created above.You can use the method of `vertx.DepLoyVerticle () to deploy verticle.
The following is an example code:
import io.vertx.core.Vertx;
public class Main {
public static void main(String[] args) {
Vertx vertx = Vertx.vertx();
vertx.deployVerticle(new MyCronVerticle());
}
}
In the above example code, we created a vertx instance and used the method of `deployverticle ()` to deploy the `mycronVerticle`.
3. Summary
Through the Vert.x Cron framework, developers can easily implement the timing task function in the vert.x application.By introducing Vert.x Cron dependencies and creating a CRON instance based on CRON expressions, developers can register tasks and perform corresponding logical code when triging a specified time.The above is the technical principle of the Vert.x Cron framework in the Java class library and related example code.
