如果你的意思是在应用程序启动后运行一次peace of code，你可以如下所示使用CommandLineRunner:

@SpringBootApplication
public class SpringBootApplication 
  implements CommandLineRunner {

private static Logger LOG = LoggerFactory
  .getLogger(SpringBootConsoleApplication.class);

public static void main(String[] args) {
    LOG.info("STARTING THE APPLICATION");
    SpringApplication.run(SpringBootConsoleApplication.class, args);
    LOG.info("APPLICATION FINISHED");
}

@Override
public void run(String... args) {
    // enter code you want to run after app loaded here
    LOG.info("EXECUTING : command line runner");

    for (int i = 0; i < args.length; ++i) {
        LOG.info("args[{}]: {}", i, args[i]);
    }
}

}

否则，您可以使用DevTools依赖项，它可以帮助您在不手动重新启动应用程序的情况下运行新代码。

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
    </dependency>
</dependencies>

不要忘记将这些代码添加到pom.xml中，以避免版本警告:

   <properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.3</spring-cloud.version>
    </properties>

 <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>${spring-cloud.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>

如果这对你有帮助，给它一个重击!

ApplicationReadyEvent仅在您希望执行的任务不是正确服务器操作所必需的情况下才有用。启动异步任务来监视某些内容的更改就是一个很好的例子。

然而，如果你的服务器在任务完成之前处于“未准备好”状态，那么最好实现SmartInitializingSingleton，因为你会在你的REST端口被打开和你的服务器为业务打开之前得到回调。

不要试图将@PostConstruct用于只应该发生一次的任务。当你注意到它被多次调用时，你会感到粗鲁的惊讶……

在春季> 4.1中使用SmartInitializingSingleton bean

@Bean
public SmartInitializingSingleton importProcessor() {
    return () -> {
        doStuff();
    };

}

作为备选方案，CommandLineRunner bean可以实现，也可以使用@PostConstruct注释bean方法。

你试过ApplicationReadyEvent吗?

@Component
public class ApplicationStartup 
implements ApplicationListener<ApplicationReadyEvent> {

  /**
   * This event is executed as late as conceivably possible to indicate that 
   * the application is ready to service requests.
   */
  @Override
  public void onApplicationEvent(final ApplicationReadyEvent event) {

    // here your code ...

    return;
  }
}

代码来自:http://blog.netgloo.com/2014/11/13/run-code-at-spring-boot-startup/

下面是文档中提到的启动事件:

... Application events are sent in the following order, as your application runs: An ApplicationStartedEvent is sent at the start of a run, but before any processing except the registration of listeners and initializers. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context is known, but before the context is created. An ApplicationPreparedEvent is sent just before the refresh is started, but after bean definitions have been loaded. An ApplicationReadyEvent is sent after the refresh and any related callbacks have been processed to indicate the application is ready to service requests. An ApplicationFailedEvent is sent if there is an exception on startup. ...

为Dave Syer的回答提供了一个例子，这就像一个魅力:

@Component
public class CommandLineAppStartupRunner implements CommandLineRunner {
    private static final Logger logger = LoggerFactory.getLogger(CommandLineAppStartupRunner.class);

    @Override
    public void run(String...args) throws Exception {
        logger.info("Application started with command-line arguments: {} . \n To kill this application, press Ctrl + C.", Arrays.toString(args));
    }
}

如果你的意思是在应用程序启动后运行一次peace of code，你可以如下所示使用CommandLineRunner:

@SpringBootApplication
public class SpringBootApplication 
  implements CommandLineRunner {

private static Logger LOG = LoggerFactory
  .getLogger(SpringBootConsoleApplication.class);

public static void main(String[] args) {
    LOG.info("STARTING THE APPLICATION");
    SpringApplication.run(SpringBootConsoleApplication.class, args);
    LOG.info("APPLICATION FINISHED");
}

@Override
public void run(String... args) {
    // enter code you want to run after app loaded here
    LOG.info("EXECUTING : command line runner");

    for (int i = 0; i < args.length; ++i) {
        LOG.info("args[{}]: {}", i, args[i]);
    }
}

}

否则，您可以使用DevTools依赖项，它可以帮助您在不手动重新启动应用程序的情况下运行新代码。

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
    </dependency>
</dependencies>

不要忘记将这些代码添加到pom.xml中，以避免版本警告:

   <properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.3</spring-cloud.version>
    </properties>

 <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>${spring-cloud.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>

如果这对你有帮助，给它一个重击!