Multiple writers or readers.

[E-Werk]

Hi guys,


i have a question about spring batch. The other day i was reading the book "Spring Batch In Action" and there was a statement that was saying that every step is formed by three elements: a reader, a processor and a writer. So my question is: Is it possible to have more than one reader or writer associated to a step ?

Example for writer: Imagine you would like to write the processed data to a file and to a database, or to two different databases.

If this is not possible, how can we achieve this behavior ?

Thank you.

[michael.lange]

out of the box you can:

• chain item processors
• chain item writers

for more than one reader i have an example in my github repository, but this is a "unify all read items from all readers to one item for each read sequence"

example spring configuration:

    <bean id="compositeItemReader" class="de.langmi.spring.batch.examples.readers.support.CompositeItemStreamReader">
        <property name="unifyingMapper">
            <bean class="de.langmi.spring.batch.examples.readers.support.DefaultUnifyingStringItemsMapper" />
        </property>
        <property name="itemReaderStreams">
            <list>
                <ref bean="itemReader1" />
                <ref bean="itemReader2" />
            </list>
        </property>
    </bean>

    <bean id="itemReader1" class="org.springframework.batch.item.file.FlatFileItemReader" scope="step">
        <property name="name" value="itemReader1" />
        <property name="resource" value="#{jobParameters['input.file.1']}" />
        <property name="lineMapper">
            <bean class="org.springframework.batch.item.file.mapping.PassThroughLineMapper" />
        </property>
        <property name="strict" value="true" />
    </bean>

    <bean id="itemReader2" class="org.springframework.batch.item.file.FlatFileItemReader" scope="step">
        <property name="name" value="itemReader2" />
        <property name="resource" value="#{jobParameters['input.file.2']}" />
        <property name="lineMapper">
            <bean class="org.springframework.batch.item.file.mapping.PassThroughLineMapper" />
        </property>
        <property name="strict" value="true" />
    </bean>

[E-Werk]

Thank you, that helped.