How to access item data (e.g. total # of records) in headerCallBack's write method?

[nikunj_c]

My Job is as below:

<job id="helloWorldJob">
    <step id="step1">
        <tasklet>
            <chunk reader="empReader" processor="empProcessor" writer="empHeaderFooterWriter" commit-interval="1000"/>
        </tasklet>
    </step>
</job>

My writer is as below:

<beans:bean id="empWriter" class="org.springframework.batch.item.file.FlatFileItemWriter">
    <beans:property name="resource" value="file:target/output_data.txt" />
    <beans:property name="lineAggregator">
        <beans:bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
            <beans:property name="delimiter" value=","/>
            <beans:property name="fieldExtractor">
                <beans:bean class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
                    <beans:property name="names" value="empId,lastName,title,salary,rank"/>
                </beans:bean>
            </beans:property>
        </beans:bean>
    </beans:property>
    <beans:property name="footerCallback" ref="empHeaderFooterWriter" />
    <beans:property name="headerCallback" ref="empHeaderFooterWriter" />
</beans:bean>

<beans:bean id="empHeaderFooterWriter" class="com.test.EmployeeItemWriter">
    <beans:property name="delegate" ref="empWriter"/>
</beans:bean>

Now what I want to do is, I want to put the total number of records in the file in the Header (and not in footer).

How can I do that ??

Thanks,
Nik

[michael.lange]

You could try and change the header of the file in an after step with Replace first line of a text file in Java with RandomAccessFile

[nikunj_c]

Thanks a lot Michael!! that helped!!

[Prabhabati Moharana]

Hi Michel

how to set the item data(e.g total # of records from db) in headercallback's write method..

Here config file is as below

<bean id="itemWriter" class="org.springframework.batch.item.xml.StaxEventItemWriter">
			<property name="resource" ref="outputResource" />
	      	<property name="marshaller" ref="LedgerMarshaller" />    
       		<property name="rootTagName" value="BatchJob" />
       		 <property name="headerCallback" ref="headerCallback" />     		
       		     
 </bean>

and classes for as below

public class ProductHeaderStaxCallback implements StaxWriterCallback {

    @Override
    public void write(XMLEventWriter writer) throws IOException {
        try {
        	
        	
        	
        	
            XMLEventFactory eventFactory = XMLEventFactory.newInstance();

            XMLEvent event = eventFactory.createStartElement("", "", "source");
            writer.add(event);
           // event = eventFactory.createAttribute("generated", DateFormat.getDateTimeInstance().format(new Date()));
           // writer.add(event);
            Characters studentNameChars = eventFactory.createCharacters("scan");
            writer.add(studentNameChars); 
            event = eventFactory.createEndElement("", "", "source");
            writer.add(event);
            XMLEvent event1 = eventFactory.createStartElement("", "", "Datetime");
            writer.add(event1);
            //event1 = eventFactory.createAttribute("generated", DateFormat.getDateTimeInstance().format(new Date()));
          //  writer.add(event1);
            Characters studentNameChars1 = eventFactory.createCharacters(DateFormat.getDateTimeInstance().format(new Date()));
            writer.add(studentNameChars1); 
            event1 = eventFactory.createEndElement("", "", "Datetime");
            writer.add(event1);
            Ledger ledger = Ledger.getInstance();
        	ledger.getRowcount();        	System.out.println("RowCount!!!"+ledger.getRowcount());
        } catch (XMLStreamException e) {
        }

    }

I have tried with above, getting null value as rowcount .

[michael.lange]

i do not understand the code :-)

Ledger ledger = Ledger.getInstance();
ledger.getRowcount();

what happens inside Ledget.getInstance ?

anyways

how to set the item data(e.g total # of records from db) in headercallback's write method..

from above

You could try and change the header of the file in an after step with Replace first line of a text file in Java with RandomAccessFile