Resolving Bean Scope Issues in Java Spring Batch with Configurable Application Context
When working with Spring Batch, creating and managing beans can sometimes lead to unexpected issues, especially when dealing with circular dependencies or scope-related problems. Recently, I encountered such a challenge while trying to dynamically configure Spring Batch jobs based on a list of job names. Each job included multiple steps, and one of these steps was configured using a method annotated with @Bean. This setup caused a circular dependency issue that required careful restructuring to resolve. Here, I’ll share my approach and solution to this problem.
The Scenario
Let’s assume you’re working on a Spring Batch project where jobs are configured dynamically based on a predefined list of names. Each job comprises multiple steps, most of which are straightforward and configured programmatically. However, one specific step is configured using a method annotated with @Bean. This causes a circular dependency because the method is called during job configuration, which occurs while the application context is still being initialized.
Here’s what the configuration might look like:
Job Configuration Example
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.util.List;
@Configuration
public class BatchConfig {
private final JobBuilderFactory jobBuilderFactory;
private final StepBuilderFactory stepBuilderFactory;
private final ApplicationContext applicationContext;
public BatchConfig(JobBuilderFactory jobBuilderFactory, StepBuilderFactory stepBuilderFactory, ApplicationContext applicationContext) {
this.jobBuilderFactory = jobBuilderFactory;
this.stepBuilderFactory = stepBuilderFactory;
this.applicationContext = applicationContext;
}
@Bean
public List<String> jobNames() {
return List.of("job1", "job2", "job3");
}
public void configureJobs() {
AnnotationConfigApplicationContext configurableContext = (AnnotationConfigApplicationContext) applicationContext;
jobNames().forEach(jobName -> {
Job job = createJob(jobName);
configurableContext.getBeanFactory().registerSingleton(jobName, job);
});
}
private Job createJob(String jobName) {
return jobBuilderFactory.get(jobName)
.start(createStep(jobName))
.next(methodAnnotatedWithBean()) // Calls the problematic method
.build();
}
private Step createStep(String name) {
return stepBuilderFactory.get(name)
.tasklet((contribution, chunkContext) -> {
System.out.println(name + " Step executed");
return null;
})
.build();
}
@Bean
public Step methodAnnotatedWithBean() {
return stepBuilderFactory.get("specialStep")
.tasklet((contribution, chunkContext) -> {
System.out.println("Special Step executed");
return null;
})
.build();
}
}
The Problem
In this setup, the methodAnnotatedWithBean method is annotated with @Bean and is directly called during the job configuration. This causes a circular dependency because Spring tries to initialize the bean while simultaneously resolving the configuration class that defines it. This results in an error and prevents the application context from starting.
The Solution
To resolve this, I made the following adjustments:
Updated Configuration
@Configuration
public class BatchConfigFixed {
private final JobBuilderFactory jobBuilderFactory;
private final StepBuilderFactory stepBuilderFactory;
private final ApplicationContext applicationContext;
public BatchConfigFixed(JobBuilderFactory jobBuilderFactory, StepBuilderFactory stepBuilderFactory, ApplicationContext applicationContext) {
this.jobBuilderFactory = jobBuilderFactory;
this.stepBuilderFactory = stepBuilderFactory;
this.applicationContext = applicationContext;
}
@Bean
public List<String> jobNames() {
return List.of("job1", "job2", "job3");
}
public void configureJobs() {
AnnotationConfigApplicationContext configurableContext = (AnnotationConfigApplicationContext) applicationContext;
jobNames().forEach(jobName -> {
Job job = createJob(jobName);
configurableContext.getBeanFactory().registerSingleton(jobName, job);
});
}
private Job createJob(String jobName) {
return jobBuilderFactory.get(jobName)
.start(createStep(jobName))
.next(createSpecialStep()) // Refactored method
.build();
}
private Step createStep(String name) {
return stepBuilderFactory.get(name)
.tasklet((contribution, chunkContext) -> {
System.out.println(name + " Step executed");
return null;
})
.build();
}
private Step createSpecialStep() {
return stepBuilderFactory.get("specialStep")
.tasklet((contribution, chunkContext) -> {
System.out.println("Special Step executed");
return null;
})
.build();
}
}
Here, the methodAnnotatedWithBean has been replaced with a standard private method (createSpecialStep) that is programmatically called during job creation. This avoids the circular dependency issue entirely.
Conclusion
The key takeaway is to avoid directly invoking methods annotated with @Bean during dynamic configuration. Instead, use programmatic definitions for components like steps that are dynamically included in jobs. This ensures that lifecycle management is straightforward and avoids circular dependency issues.
This approach not only resolved the issue in my Spring Batch project but also streamlined the configuration process. I hope this example helps others facing similar challenges!