Spring Batch, variable through the steps of a job

Question

I'm trying to create a job in Spring Batch but I can't find something.. My program looks like that :

• A tasklet wich create a list of ids
• A Reader that use this list to get a String in the database and concatenated them
• A Writer that take this String and write it in a file
• A tasket that use the list of ids and update the database.

First, is it the best choice for the structure of my batch ?

The main problem is that I don't know how to get the list of ids in the Reader and in the last Tasklet. I'm using Spring and I've tried this :

    <bean id="idList" class="java.util.ArrayList" scope="job" />

    <bean id="myFirstTasklet" class="myFirstTasklet"
        <property name="idList" ref="idList" />
    </bean>

    <bean id="myReader" class="myReader"
        <property name="idList" ref="idList" />
    </bean>

    <bean id="mySecondTasklet" class="mySecondTasklet"
        <property name="idList" ref="idList" />
    </bean>

Can my list be updated by the tasklet before the creation of the Reader and the second tasklet ?

Answer 1

You can put the value in ExecutionContext of tasklet and then later retrieve it in other tasklet. See the code below:

Inside 1st tasklet-

public RepeatStatus execute(StepContribution stepContribution,
        ChunkContext chunkContext) throws Exception {

//Putting value in Execution Context
chunkContext.getStepContext().getStepExecution().getJobExecution()
            .getExecutionContext()
            .put(Constants.DATA_LIST, idList);

}

Inside 2nd tasklet:

public RepeatStatus execute(StepContribution contribution,
        ChunkContext chunkContext) throws Exception {

//Retrieving value from Execution context
(ArrayList) chunkContext.getStepContext()
            .getStepExecution().getJobExecution().getExecutionContext()
            .get(Constants.DATA_LIST);

 }

Also ensure to mark the scope of your tasklet as step:

<bean id="mySecondTasklet" class="mySecondTasklet" scope="step" >