CODEWITHSUNDEEP
spring-batch
eloweyn
eloweyn

Reputation: 125

Write a Spring batch custom item writer

I need to write a Spring batch custom item writer that uses a footer, but I can't use the delegate pattern. Is there another way to write a Spring batch custom item writer?

Thank you in advance.

Upvotes: 2

Views: 18400

Answers (3)

eloweyn
eloweyn

Reputation: 125

I've found the solution. I can't write a custom itemwriter, but I created a bean out and I have overridden the toString method. In this method I have set the output to the file as needed. Then, I created a PassThroughLineAggregator type itemwriter. This itemwriter calls the toString method of the bean output. And that's all!!

Here's the code: MOH_Diaria_Bean_Out.java:

package es.lac.absis.batch.app.percai.domain;

import java.util.ArrayList;
import java.util.List;

public class MOH_Diaria_Bean_Out {
    List<MOH_Diaria_Bean> listaBeans = new ArrayList<MOH_Diaria_Bean>();

    public List<MOH_Diaria_Bean> getListaBeans() {
        return listaBeans;
    }

    public void setListaBeans(List<MOH_Diaria_Bean> listaBeans) {
        this.listaBeans = listaBeans;
    }

    public void add (MOH_Diaria_Bean bean){
        listaBeans.add(bean);
    }

    @Override
    public String toString() {
        // TODO Auto-generated method stub
        String salida="";
        for (int j=0; j<listaBeans.size(); j++) {
            MOH_Diaria_Bean bean = listaBeans.get(j);
            salida = salida + bean.toString();
            if (j<(listaBeans.size()-1)) {
                salida = salida + "\n";
            }       
        }
        return salida;
    }
}

ItemWriter:

<bean id="MOH_FusionadoFicheros_Writer" class="es.lac.absis.batch.arch.internal.writer.AbsisFlatFileItemWriter">
        <property name="resource">
            <bean class="es.lac.absis.batch.arch.internal.util.AbsisFileSystemResource"> 
                <constructor-arg ref="filePCA00020"></constructor-arg> 
            </bean>
        </property>
        <property name="encoding" value="ISO8859_1"></property> 
        <property name="lineAggregator">
            <bean class="org.springframework.batch.item.file.transform.PassThroughLineAggregator">
            </bean>
        </property>
</bean>

Upvotes: -1

Luca Basso Ricci
Luca Basso Ricci

Reputation: 18413

Create a custom ItemWriter that implements ItemStream (to manage restartability and footer writing) and overwrite the next methods:

  • ItemWrite.write(List<> items): write items and during writing perform necessary data calculation for footer
  • ItemStream.update(ExecutionContext): save calculated footer data in write() method
  • ItemStream.open(ExecutionContext): restore previously saved footer data
  • ItemStream.close(): do real footer writing (directly in your own writer or using a callback)

Upvotes: 5

dimzak
dimzak

Reputation: 2571

Check here

Basically you need to create a class that implements ItemWriter<YourModel> and FlatFileFooterCallback

In the write method, enter how data will be written and in the writeFooter the footer of the file.
Then declare your class as a bean and put it as a writer in your job.

Upvotes: 0

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