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应用程序的初始化和终止

You often need to execute custom actions when the application starts and clean up everything when the application stops. This guide explains how to:

  • Write a Quarkus application with a main method

  • Write command mode applications that run a task and then terminate

  • Be notified when the application starts

  • Be notified when the application stops

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 3.9.6

  • 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)

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 lifecycle-quickstart directory.

创建Maven项目

首先,我们需要一个新的项目。使用以下命令创建一个新项目:

CLI
quarkus create app org.acme:lifecycle-quickstart \
    --no-code
cd lifecycle-quickstart

创建Grade项目,请添加 --gradle 或者 --gradle-kotlin-dsl 参数。

For more information about how to install and use the Quarkus CLI, see the Quarkus CLI guide.

Maven
mvn io.quarkus.platform:quarkus-maven-plugin:3.11.3:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=lifecycle-quickstart \
    -DnoCode
cd lifecycle-quickstart

创建Grade项目,请添加 -DbuildTool=gradle 或者 -DbuildTool=gradle-kotlin-dsl 参数。

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=lifecycle-quickstart"

It generates:

  • Maven的结构

  • example Dockerfile files for both native and jvm modes

  • 应用程序的配置文件

The main method

By default, Quarkus will automatically generate a main method, that will bootstrap Quarkus and then just wait for shutdown to be initiated. Let’s provide our own main method:

package com.acme;

import io.quarkus.runtime.annotations.QuarkusMain;
import io.quarkus.runtime.Quarkus;

@QuarkusMain  (1)
public class Main {

    public static void main(String ... args) {
        System.out.println("Running main method");
        Quarkus.run(args); (2)
    }
}
1 This annotation tells Quarkus to use this as the main method, unless it is overridden in the config
2 This launches Quarkus

This main class will bootstrap Quarkus and run it until it stops. This is no different to the automatically generated main class, but has the advantage that you can just launch it directly from the IDE without needing to run a Maven or Gradle command.

It is not recommenced to do any business logic in this main method, as Quarkus has not been set up yet, and Quarkus may run in a different ClassLoader. If you want to perform logic on startup use an io.quarkus.runtime.QuarkusApplication as described below.

If we want to actually perform business logic on startup (or write applications that complete a task and then exit) we need to supply a io.quarkus.runtime.QuarkusApplication class to the run method. After Quarkus has been started the run method of the application will be invoked. When this method returns the Quarkus application will exit.

If you want to perform logic on startup you should call Quarkus.waitForExit(), this method will wait until a shutdown is requested (either from an external signal like when you press Ctrl+C or because a thread has called Quarkus.asyncExit()).

An example of what this looks like is below:

package com.acme;

import io.quarkus.runtime.Quarkus;
import io.quarkus.runtime.QuarkusApplication;
import io.quarkus.runtime.annotations.QuarkusMain;

@QuarkusMain
public class Main {
    public static void main(String... args) {
        Quarkus.run(MyApp.class, args);
    }

    public static class MyApp implements QuarkusApplication {

        @Override
        public int run(String... args) throws Exception {
            System.out.println("Do startup logic here");
            Quarkus.waitForExit();
            return 0;
        }
    }
}

Quarkus.run also provides a version that allows the code to handle errors. For example:

package com.acme;

import io.quarkus.runtime.Quarkus;
import io.quarkus.runtime.QuarkusApplication;
import io.quarkus.runtime.annotations.QuarkusMain;

@QuarkusMain
public class Main {
    public static void main(String... args) {
        Quarkus.run(MyApp.class,
        (exitCode, exception) -> {
            // do whatever
        },
        args);
    }

    public static class MyApp implements QuarkusApplication {

        @Override
        public int run(String... args) throws Exception {
            System.out.println("Do startup logic here");
            Quarkus.waitForExit();
            return 0;
        }
    }
}

Injecting the command line arguments

It is possible to inject the arguments that were passed in on the command line:

@Inject
@CommandLineArguments
String[] args;

Command line arguments can be passed to the application through the -D flag with the property quarkus.args:

  • For Quarkus dev mode:

    CLI
    quarkus dev -Dquarkus.args=cmd-args
    Maven
    ./mvnw quarkus:dev -Dquarkus.args=cmd-args
    Gradle
    ./gradlew --console=plain quarkusDev -Dquarkus.args=cmd-args
  • For a runner jar: java -Dquarkus.args=<cmd-args> -jar target/quarkus-app/quarkus-run.jar

  • For a native executable: ./target/lifecycle-quickstart-1.0-SNAPSHOT-runner -Dquarkus.args=<cmd-args>

Listening for startup and shutdown events

Create a new class named AppLifecycleBean (or pick another name) in the org.acme.lifecycle package, and copy the following content:

package org.acme.lifecycle;

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.enterprise.event.Observes;

import io.quarkus.runtime.ShutdownEvent;
import io.quarkus.runtime.StartupEvent;
import org.jboss.logging.Logger;

@ApplicationScoped
public class AppLifecycleBean {

    private static final Logger LOGGER = Logger.getLogger("ListenerBean");

    void onStart(@Observes StartupEvent ev) {               (1)
        LOGGER.info("The application is starting...");
    }

    void onStop(@Observes ShutdownEvent ev) {               (2)
        LOGGER.info("The application is stopping...");
    }

}
1 Method called when the application is starting
2 Method called when the application is terminating
The events are also called in dev mode between each redeployment.
The methods can access injected beans. Check the AppLifecycleBean.java class for details.

What is the difference from @Initialized(ApplicationScoped.class) and @Destroyed(ApplicationScoped.class)

In the JVM mode, there is no real difference, except that StartupEvent is always fired after @Initialized(ApplicationScoped.class) and ShutdownEvent is fired before @Destroyed(ApplicationScoped.class). For a native executable build, however, @Initialized(ApplicationScoped.class) is fired as part of the native build process, whereas StartupEvent is fired when the native image is executed. See Three Phases of Bootstrap and Quarkus Philosophy for more details.

In CDI applications, an event with qualifier @Initialized(ApplicationScoped.class) is fired when the application context is initialized. See the spec for more info.

Using @Startup to initialize a CDI bean at application startup

A bean represented by a class, producer method or field annotated with @Startup is initialized at application startup:

package org.acme.lifecycle;

import io.quarkus.runtime.Startup;
import jakarta.enterprise.context.ApplicationScoped;

@Startup (1)
@ApplicationScoped
public class EagerAppBean {

   private final String name;

   EagerAppBean(NameGenerator generator) { (2)
     this.name = generator.createName();
   }
}
1 For each bean annotated with @Startup a synthetic observer of StartupEvent is generated. The default priority is used.
2 The bean constructor is called when the application starts and the resulting contextual instance is stored in the application context.
@Dependent beans are destroyed immediately afterwards to follow the behavior of observers declared on @Dependent beans.
If a class is annotated with @Startup but with no scope annotation then @ApplicationScoped is added automatically.

The @Startup annotation can be also declared on a non-static non-producer no-args method:

package org.acme.lifecycle;

import io.quarkus.runtime.Startup;
import jakarta.enterprise.context.ApplicationScoped;

@ApplicationScoped
public class EagerAppBean {

   @Startup
   void init() { (1)
     doSomeCoolInit();
   }
}
1 The bean is created and the init() method is invoked upon the contextual instance when the application starts.

Using @Shutdown to execute a business method of a CDI bean during application shutdown

The @io.quarkus.runtime.Shutdown annotation is used to mark a business method of a CDI bean that should be executed during application shutdown. The annotated method must be non-private and non-static and declare no arguments. The behavior is similar to a declaration of a ShutdownEvent observer. The following examples are functionally equivalent.

import io.quarkus.runtime.Shutdown;
import io.quarkus.runtime.ShutdownEvent;
import jakarta.enterprise.context.ApplicationScoped;

@ApplicationScoped
class Bean1 {
   void onShutdown(@Observes ShutdownEvent event) {
      // place the logic here
   }
}

@ApplicationScoped
class Bean2 {

   @Shutdown
   void shutdown() {
      // place the logic here
   }
}

打包并运行该应用程序

使用以下命令运行该应用程序:

CLI
quarkus dev
Maven
./mvnw quarkus:dev
Gradle
./gradlew --console=plain quarkusDev

The logged message is printed. When the application is stopped, the second log message is printed.

像往常一样,该应用程序可以用以下方式打包:

CLI
quarkus build
Maven
./mvnw install
Gradle
./gradlew build

and executed using java -jar target/quarkus-app/quarkus-run.jar.

You can also generate the native executable using:

CLI
quarkus build --native
Maven
./mvnw install -Dnative
Gradle
./gradlew build -Dquarkus.native.enabled=true

Launch Modes

Quarkus has 3 different launch modes, NORMAL (i.e. production), DEVELOPMENT and TEST. If you are running quarkus:dev then the mode will be DEVELOPMENT, if you are running a JUnit test it will be TEST, otherwise it will be NORMAL.

Your application can get the launch mode by injecting the io.quarkus.runtime.LaunchMode enum into a CDI bean, or by invoking the static method io.quarkus.runtime.LaunchMode.current().

Graceful Shutdown

Quarkus includes support for graceful shutdown, this allows Quarkus to wait for running requests to finish, up till a set timeout. By default, this is disabled, however you can configure this by setting the quarkus.shutdown.timeout config property. When this is set shutdown will not happen until all running requests have completed, or until this timeout has elapsed.

Extensions that accept requests need to add support for this on an individual basis. At the moment only the HTTP extension supports this, so shutdown may still happen when messaging requests are active.

Quarkus supports a delay time, where the application instance still responds to requests, but the readiness probe fails. This gives the infrastructure time to recognize that the instance is shutting down and stop routing traffic to the instance. This feature can be enabled by setting the build-time property quarkus.shutdown.delay-enabled to true. The delay can then be configured by setting the runtime property quarkus.shutdown.delay. It is not set by default, thus no delay is applied.

To write duration values, use the standard java.time.Duration format. See the Duration#parse() javadoc for more information.

You can also use a simplified format, starting with a number:

  • If the value is only a number, it represents time in seconds.

  • If the value is a number followed by ms, it represents time in milliseconds.

In other cases, the simplified format is translated to the java.time.Duration format for parsing:

  • If the value is a number followed by h, m, or s, it is prefixed with PT.

  • If the value is a number followed by d, it is prefixed with P.

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