Spring Boot & Spring Batch auto wiring - spring

Question

I'm trying to get me head around Spring Boot's auto wiring for Spring Batch. In the example in the Spring docs, there are a number of parameters being passed in the constructor to some beans.
The example works, but if I try to create another job using the identical configuration (naming it importUserJob2), I get a non-unique bean exception - the error reports there are 2 step beans.
#Bean
public Job importUserJob(JobBuilderFactory jobs, Step s1, JobExecutionListener listener) {
return jobs.get("importUserJob")
.incrementer(new RunIdIncrementer())
.listener(listener)
.flow(s1)
.end()
.build();
}
What does the constructor here mean when used with parameters (I can't see where these parameters are supplied) and where are these beans being created? How do I create 2 jobs?
EDIT: here are the 2 jobs, 2 steps and the exception I get.
#Bean
public Job helloJob(JobBuilderFactory jobs, Step s1, JobExecutionListener listener) {
return jobs.get("helloJob")
.incrementer(new RunIdIncrementer())
.listener(listener)
.flow(s1)
.end()
.build();
}
#Bean
public Step step1(StepBuilderFactory stepBuilderFactory) {
return stepBuilderFactory.get("step1")
.tasklet(helloTasklet())
.build();
}
#Bean
public Job otherJob(JobBuilderFactory jobs, Step s1, JobExecutionListener listener) {
return jobs.get("otherJob")
.incrementer(new RunIdIncrementer())
.listener(listener)
.flow(s1)
.end()
.build();
}
#Bean
public Step step2(StepBuilderFactory stepBuilderFactory, ItemReader<MyReadItem> reader,
ItemWriter< MyReadItem > writer) {
return stepBuilderFactory.get("step2")
.< MyReadItem, MyReadItem > chunk(10)
.reader(reader)
.writer(writer)
.build();
}
And the exception:
nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [org.springframework.batch.core.Step] is defined: expected single matching bean but found 2: step1,step2
What creates Step s1? Am I right in thinking that Spring just looks for any bean that is the correct type (Step), but there are 2 found? Do I need to qualify the steps when they're created to ensure the correct one is injected??

Answer 1

In both your job definitions methods, you are using "Step s1" as a parameter. Since "s1" is not a name of a bean, spring will try to autowire by type. However, it will find two steps ("step1" and "step2") in the context. I guess, that's the reason for your exception.
You could either change the names in your parameter, or call directly the method in your definitions:
#Bean
public Job otherJob(JobBuilderFactory jobs, JobExecutionListener listener) {
return jobs.get("otherJob")
.incrementer(new RunIdIncrementer())
.listener(listener)
.flow(step2())
.end()
.build();
}
Spring takes care, that it not simply calls the step2 method, but instead provides a real spring-bean.