java - 在使用 Spring Batch 和 Spring Boot 时，如何始终为每次运行启动一个新的作业实例？

Question

在使用 Spring Batch 和 Spring Boot 时，我们将得到一个 Fat jar，其中包含我所有的 Spring Batch 作业，我希望能够通过指定作业名称从命令行触发特定作业，问题是spring batch 检测到作业已完成，因此只会运行一次作业，使用 spring boot，我们可以使用 --spring.batch.job.names=jobToRun 指定名称，问题是如何我让它始终启动一个新实例，并且仍然能够使用此机制来传递要运行的作业名称。

我没有配置JobLauncher，所以我猜它使用的是默认的JobLauncherCommandLineRunner，我当前配置的是:

@SpringBootApplication
@EnableBatchProcessing
public class Application {
  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }
}

通过此配置，我可以从命令行运行该作业:

java -jar batch.jar --spring.batch.job.names=job1ToRun

如何使用类似的机制为每次运行启动一个新实例？我需要从命令行指定作业名称来选择要运行的作业。

Answer 1

来自spring-batch documentation

The CommandLineJobRunner

Because the script launching the job must kick off a Java Virtual Machine, there needs to be a class with a main method to act as the primary entry point. Spring Batch provides an implementation that serves just this purpose: CommandLineJobRunner. It's important to note that this is just one way to bootstrap your application, but there are many ways to launch a Java process, and this class should in no way be viewed as definitive. The CommandLineJobRunner performs four tasks:

• Load the appropriate ApplicationContext
• Parse command line arguments into JobParameters
• Locate the appropriate job based on arguments
• Use the JobLauncher provided in the application context to launch the job.

一个非常基本的示例，说明如何执行此操作:

 public static void main(String[] args) throws Exception {
    ConfigurableApplicationContext ctx = SpringApplication.run(Application.class, args);
    JobLauncher jobLauncher = ctx.getBean(JobLauncher.class);
    String jobName = args[0] // assuming args[0] is the jobName
    JobParameters jobParameters = createJobParameters(args)
    Job jobInstance = ctx.getBean(jobName, Job.class);          
    jobLauncher.run(jobInstance, jobParameters);                   
}

private static JobParameters createJobParameters(String[] args) {
    // TODO: Create & return the needed parameters 
}