Is it possible to dynamically create a resource name? - spring

Question

I'm writing to a CSV file and using FlatFileItemWriter to do it. I have a bean with that as my class, and I also have a property for the resource, where I provide the file name to use to write out the item.
Is it possible to append the date and time to the file name?
Right now I am telling it to write out to a file called report.csv, instead I want it to write out to a file called report-7-2-2014-16-03.csv
Here's the XML Config for the writer
<bean id="csvWriter" class="org.springframework.batch.item.file.FlatFileItemWriter">
<property name="resource">
<bean class="org.springframework.core.io.FileSystemResource">
<constructor-arg value="${REPORT_FILENAME}" />
</bean>
</property>
<property name="shouldDeleteIfExists" value="true" />
<property name="lineAggregator">
<bean class="com.example.CSVLineAggregator" />
</property>
<property name="headerCallback">
<bean class="com.example.CSVHeaderWriter" >
<constructor-arg value="${REPORT_HEADER}" />
</bean>
</property>
</bean>

Answer 1

You need to configure your step with late binding to solve your problem.
Late binding allow you to evaluate an expression during job/step execution and not in a static way (during xml pasring, to be clear) using values stored in jobParameters and job or step execution context; thise contexts are available only during job/step execution!
To enable this feature:
mark your artifacts with special step="scope"
Add to jobParameters with name 'REPORT_FILENAME' and value 'report-7-2-2014-16-03.csv' (of course this value will change every time you launch the job and is your reponsibility to make it unique and create with right date/time)
use spEL with special #{jobParameters['REPORT_FILENAME']} expression to let SB extract the report name from job parameters dinamically
<bean id="csvWriter" class="org.springframework.batch.item.file.FlatFileItemWriter" scope="step">
<property name="resource" value="file://report-dir/#{jobParameters['REPORT_FILENAME']}" />
<property name="shouldDeleteIfExists" value="true" />
<property name="lineAggregator">
<bean class="com.example.CSVLineAggregator" />
</property>
<property name="headerCallback">
<bean class="com.example.CSVHeaderWriter" >
<constructor-arg value="${REPORT_HEADER}" />
</bean>
</property>
</bean>
This is just a small example but you can read more about Late binding