Spring Batch – Read once, Write multi example

Sometimes, we need to read once, write multi ETL with Spring Batch. Spring Batch supports it with CompositeItemWriter (org.springframework.batch.item.support.CompositeItemWriter).

Sample table schema

CREATE TABLE "TB_SOURCE"
   (	"COL1" VARCHAR2(10 BYTE),
	"COL2" VARCHAR2(20 BYTE),
	"COL3" VARCHAR2(20 BYTE)
   );

CREATE TABLE "TB_TARGET1"
   (	"NEW_COL1" VARCHAR2(10 BYTE),
	"NEW_COL2" VARCHAR2(20 BYTE)
   );

  CREATE TABLE "TB_TARGET2"
   (	"NEW_COL1" VARCHAR2(10 BYTE),
	"NEW_COL3" VARCHAR2(20 BYTE)
   );

Declaration of CompositeItemWriter

	<bean id="TestCompositeWriter"
	class="org.springframework.batch.item.support.CompositeItemWriter"
	scope="step">
	<property name="delegates">
	<list>
	<ref bean="TestWriter1"/>
	<ref bean="TestWriter2"/>
	</list>
	</property>
	</bean>
	<bean id="TestWriter1"
	class="org.springframework.batch.item.database.JdbcBatchItemWriter"
	scope="step">
	<property name="assertUpdates" value="true" />
	<property name="itemSqlParameterSourceProvider">
	<bean class="org.springframework.batch.item.database.BeanPropertyItemSqlParameterSourceProvider" />
	</property>
	<property name="sql"
	value="INSERT INTO TB_TARGET1(NEW_COL1, NEW_COL2)
	VALUES(:newCol1, :newCol2)"
	/>
	<property name="dataSource" ref="testDataSource" />
	</bean>
	<bean id="TestWriter2"
	class="org.springframework.batch.item.database.JdbcBatchItemWriter"
	scope="step">
	<property name="assertUpdates" value="true" />
	<property name="itemSqlParameterSourceProvider">
	<bean class="org.springframework.batch.item.database.BeanPropertyItemSqlParameterSourceProvider" />
	</property>
	<property name="sql"
	value="INSERT INTO TB_TARGET2(NEW_COL1, NEW_COL3)
	VALUES(:newCol1, :newCol3)"
	/>
	<property name="dataSource" ref="testDataSource" />
	</bean>

view raw spring_batch_test.composite_writer1 hosted with ❤ by GitHub

Make sure that CompositeItemWriter has 2 delegates (TestWriter1, TestWriter2). You can use any Writer as it’s delegate.

Full Job declaration

	<batch:job id="TestCompositeJob" job-repository="jobRepository">
	<batch:step id="SimpleStep">
	<batch:tasklet transaction-manager="testTransactionManager" allow-start-if-complete="true">
	<batch:chunk
	reader="TestReader"
	processor="TestProcessor"
	writer="TestCompositeWriter"
	commit-interval="1"
	reader-transactional-queue="false"
	/>
	</batch:tasklet>
	</batch:step>
	</batch:job>

view raw spring_batch_test.composite_writer2 hosted with ❤ by GitHub

Make sure that Job task is using new CompositeItemWriter instead of JdbcBatchItemWriter.

 

You can download the full sample source at https://github.com/tkstone/spring_batch_sample01

• Spring context : src/main/resources/spring/job-test-composite-context.xml
• Launcher class : test.main.TestCompositeRun.java
• Processor class : test.main.TestProcessor.java

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