How to use decider in Spring batch?

Question

I\'m new to Spring batch. I\'ve created a decider which returns a FlowExecutionStatus as \"YES\" / \"NO\". Based on the FlowExecutionStatus, I need to call step2() or step3(

Answer 1

You would need to to set the exit status in step1 so that the decider picks it up and make the decision:

@Bean
public Step step1() {

   return stepBuilderFactory.get("step1").tasklet(new Tasklet() {

       @Override
       public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception {
          System.out.println("Exiting step1() execute()");
          chunkContext.getStepContext().getStepExecution().setExitStatus(new ExitStatus("YES")); // or NO
          return RepeatStatus.FINISHED;
       }

    }).build();
}

EDIT: I thought that the decider should make the decision based on the exit status of step1, hence the previous sample. So adding a sample to show how to use a decider (after clarification):

import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobParameters;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.job.flow.FlowExecutionStatus;
import org.springframework.batch.core.job.flow.JobExecutionDecider;
import org.springframework.batch.core.launch.JobLauncher;
import org.springframework.batch.repeat.RepeatStatus;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableBatchProcessing
public class MyJob {

    @Autowired
    private JobBuilderFactory jobs;

    @Autowired
    private StepBuilderFactory steps;

    @Bean
    public Step step1() {
        return steps.get("step1")
                .tasklet((contribution, chunkContext) -> {
                    System.out.println("hello");
                    return RepeatStatus.FINISHED;
                })
                .build();
    }

    @Bean
    public JobExecutionDecider decider() {
        return (jobExecution, stepExecution) -> new FlowExecutionStatus("YES"); // or NO
    }

    @Bean
    public Step step2() {
        return steps.get("step2")
                .tasklet((contribution, chunkContext) -> {
                    System.out.println("world");
                    return RepeatStatus.FINISHED;
                })
                .build();
    }

    @Bean
    public Step step3() {
        return steps.get("step3")
                .tasklet((contribution, chunkContext) -> {
                    System.out.println("!!");
                    return RepeatStatus.FINISHED;
                })
                .build();
    }

    @Bean
    public Job job() {
        return jobs.get("job")
                .start(step1())
                .next(decider())
                    .on("YES").to(step2())
                    .from(decider()).on("NO").to(step3())
                    .end()
                .build();
    }

    public static void main(String[] args) throws Exception {
        ApplicationContext context = new AnnotationConfigApplicationContext(MyJob.class);
        JobLauncher jobLauncher = context.getBean(JobLauncher.class);
        Job job = context.getBean(Job.class);
        jobLauncher.run(job, new JobParameters());
    }

}

In this example, step1 is executed first, then the decider. If the decider returns YES, step2 is executed and if returns NO, step3 is executed.

Hope this helps.