How to use chunk processing with Spring Batch?

Question

I'm using Spring Batch for the first time. I tried some examples and read through documentation. But I have still questions:

• Can I skip one phase in chunk oriented processing? For example: I fetch data from database, process it and determine, that I need more, can I skip write phase and execute next step's read phase? Should I use Tasklet instead?

• How to implement a conditional flow?

Thank you very much, Florian

Answer 1

Skip chunks simply by throwing an exception that has been declared as "skippable exception". You can do it as follows:

<step id="step1">
   <tasklet>
      <chunk reader="reader" writer="writer"
             commit-interval="10" skip-limit="10">
         <skippable-exception-classes>
            <include class="com.myapp.batch.MyException"/>
         </skippable-exception-classes>
      </chunk>
   </tasklet>
</step>

Conditional flow can easily be implemented deciding on the ExitStatus of a step-execution:

<job id="job">
    <step id="step1" parent="s1">
        <next on="*" to="stepB" />
        <next on="FAILED" to="stepC" />
    </step>
    <step id="stepB" parent="s2" next="stepC" />
    <step id="stepC" parent="s3" />
</job>

Read the documentation to gain deeper knowledge on these topics: http://docs.spring.io/spring-batch/reference/html/configureStep.html