What are the Spring Batch "default" Context Variables?

Question

In the Spring Batch step-scope documentation, there are three unexplained spring-batch context maps: jobParameters, jobExecutionContext, and stepExecutionContext.

Springsource sample code, combined:

<bean id="flatFileItemReader" scope="step"
  class="org.springframework.batch.item.file.FlatFileItemReader">
    <property name="var1" value="#{jobParameters['input.file.name']}" />
    <property name="var2" value="#{jobExecutionContext['input.file.name']}" />
    <property name="var3" value="#{stepExecutionContext['input.file.name']}" />
</bean>

What are the default parameters available within jobParameters, jobExecutionContext, and stepExecutionContext?

There are also likely differences between what's available in Spring Batch version 1.x vs. 2.x vs. 3.x--the documentation is pretty scarce in this area.

Answer 1

There aren't any default values. Think of jobParameters, jobExecutionContext, and stepExecutionContext as glorified Maps with helper methods for different primitive data types, e.g. getInt(). They're typically accessed from the StepExecution and JobExecution objects passed to *ExecutionListeners, or injecting using value injection, e.g. @Value("#{jobParameters['foo']}").

In this case, input.file.name is just a name chosen by the developer, e.g. maybe corresponding to a command line job parameter specified to the CommandLineJobRunner.

Answer 2

#{jobParameters}, #{jobExecutionContext} and #{stepExecutionContext} are the spEL (Spring Expression Language) counterpart of JobParameters, JobExecution and StepExecution objects available in late-binding to allow non-static access to this objects values from step scoped object.

They support access as Maps so you can access the ExecutionContext associated to JobExecution and StepExecution and values stored in JobParameters.

Also check StepScope documentation for more information.