Spring batch: Create file by setting name programmatically - spring-batch

Question

I have a spring batch job (defined in xml) which generates the csv export.
Inside FlatFileItemWriter bean I am setting resource, where the name of file is set.
<bean id="customDataFileWriter" class="org.springframework.batch.item.file.FlatFileItemWriter" scope="step">
<property name="resource" value="file:/tmp/export/custom-export.csv"/>
...
Now I need to set this file name taking account a certain logic, so I need to set the file name from some java class. Any ideas?

Answer 1

Use the different builder classes of spring batch (job builder, step builder, and so on). Have a look at https://blog.codecentric.de/en/2013/06/spring-batch-2-2-javaconfig-part-1-a-comparison-to-xml/ to get an idea.

Answer 2

You can implement your own FlatFileItemWriter to override the method setResource and add your own logic to rename the file.
Here's an example implementation :
#Override
public void setResource(Resource resource) {
if (resource instanceof ClassPathResource) {
// Convert resource
ClassPathResource res = (ClassPathResource) resource;
try {
String path = res.getPath();
// Do something to "path" here
File file = new File(path);
// Check for permissions to write
if (file.canWrite() || file.createNewFile()) {
file.delete();
// Call parent setter with new resource
super.setResource(new FileSystemResource(file.getAbsolutePath()));
return;
}
} catch (IOException e) {
// File could not be read/written
}
}
// If something went wrong or resource was delegated to MultiResourceItemWriter,
// call parent setter with default resource
super.setResource(resource);
}
Another possibility exists with the use of jobParameters, if your logic can be applied before job is launched. See 5.4 Late Binding of Spring Batch Documentation.
Example :
<bean id="flatFileItemReader" scope="step" class="org.springframework.batch.item.file.FlatFileItemReader">
<property name="resource" value="#{jobParameters['input.file.name']}" />
</bean>
You can also use a MultiResourceItemWriter with a custom ResourceSuffixCreator. That will let you create 1 to n files with a common filename pattern.
Here's an example of the method getSuffix of a custom ResourceSuffixCreator :
#Override
public String getSuffix(int index) {
// Your logic
if (true)
return "XXX" + index;
else
return "";
}