Spring batch的自动运行

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一个最简单的spring batch的程序，照办官网的sample，如下

一个配置程序

 

@Configuration
@EnableBatchProcessing
@EnableAutoConfiguration
public class BatchConfiguration {

  @Autowired
  private JobBuilderFactory jobBuilderFactory;

  @Autowired
  private StepBuilderFactory stepBuilderFactory;

  @Bean
  public Step step1() {
    return stepBuilderFactory.get("step1")
        .tasklet(new Tasklet() {
          public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) {
            return null;
          }
        })
        .build();
  }

  @Bean
  public Job job(Step step1) throws Exception {
    return jobBuilderFactory.get("job1")
        .incrementer(new RunIdIncrementer())
        .start(step1)
        .build();
  }
}

 

 

 一个主程序

 

public class Main {
  public static void main(String [] args) {
    System.exit(SpringApplication.exit(SpringApplication.run(
        BatchConfiguration.class, args)));
  }
}

 你肯定会好奇，为啥Job就执行了呢？没看到调用啊

 

实际上在Spring batch的配置程序org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration里有以下代码

 

	@Bean
	@ConditionalOnMissingBean
	@ConditionalOnProperty(prefix = "spring.batch.job", name = "enabled", havingValue = "true", matchIfMissing = true)
	public JobLauncherCommandLineRunner jobLauncherCommandLineRunner(
			JobLauncher jobLauncher, JobExplorer jobExplorer) {
		JobLauncherCommandLineRunner runner = new JobLauncherCommandLineRunner(
				jobLauncher, jobExplorer);
		String jobNames = this.properties.getJob().getNames();
		if (StringUtils.hasText(jobNames)) {
			runner.setJobNames(jobNames);
		}
		return runner;
	}

 

 

也就是当配置文件里定义spring.batch.job.enabled为true，或者没定义（默认为true）的时候，会初始化一个JobLauncherCommandLineRunner的bean。

而在SpringApplication里有以下代码

 

	private void callRunners(ApplicationContext context, ApplicationArguments args) {
		List