I’m using Spring Batch is my project and I am reading csv file and splitting it to multiple files using Employee Role and making the use of Classifier and ClassifierCompositeItemWriter. I’ve make the use if MultiResourceItemWriterBuilder to build the object and create a multiple files once the itemCountLimitPerResource is reached.

Now when I’m creating multiple files provided in resource, I also need to create control/audit file for it. This will mostly be an empty file. In the below screen shot code created 7 csv file, so I also to create 7 control/audit files. How can we leaverage the code?

MyConfig.java

package com.example;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.FlatFileItemWriter;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
import org.springframework.batch.item.file.builder.FlatFileItemWriterBuilder;
import org.springframework.batch.item.file.builder.MultiResourceItemWriterBuilder;
import org.springframework.batch.item.file.mapping.DefaultLineMapper;
import org.springframework.batch.item.file.transform.DelimitedLineTokenizer;
import org.springframework.batch.item.file.transform.PassThroughLineAggregator;
import org.springframework.batch.item.support.ClassifierCompositeItemWriter;
import org.springframework.batch.item.support.builder.ClassifierCompositeItemWriterBuilder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.classify.Classifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.FileSystemResource;

import java.time.LocalDate;

@Configuration
public class MyJobConfig {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;
    @Autowired
    private StepBuilderFactory stepBuilderFactory;
    
    @Bean
    public FlatFileItemReader<Employee> itemReader() {
        DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();
        tokenizer.setNames("empId", "firstName", "lastName", "role");

        DefaultLineMapper<Employee> employeeLineMapper = new DefaultLineMapper<>();
        employeeLineMapper.setLineTokenizer(tokenizer);
        employeeLineMapper.setFieldSetMapper(new EmployeeFieldSetMapper());
        employeeLineMapper.afterPropertiesSet();

        return new FlatFileItemReaderBuilder<Employee>()
                .name("flatFileReader")
                .linesToSkip(1)
                .resource(new ClassPathResource("employee.csv"))
                .lineMapper(employeeLineMapper)
                .build();
    }

    @Bean
    public ClassifierCompositeItemWriter<Employee> classifierCompositeItemWriter() throws Exception {
        Classifier<Employee, ItemWriter<? super Employee>> classifier =
                new EmployeeClassifier(
                        javaDeveloperItemWriter(),
                        pythonDeveloperItemWriter(),
                        cloudDeveloperItemWriter());

        return new ClassifierCompositeItemWriterBuilder<Employee>()
                .classifier(classifier)
                .build();
    }

    @Bean
    public ItemWriter<Employee> javaDeveloperItemWriter() {
        FlatFileItemWriter<Employee> itemWriter = new FlatFileItemWriterBuilder<Employee>()
                .lineAggregator(new PassThroughLineAggregator<>())
                .name("itemsWriter")
                .build();

        return new MultiResourceItemWriterBuilder<Employee>()
                .name("javaDeveloperItemWriter")
                .delegate(itemWriter)
                .resource(new FileSystemResource("AAA01.CPP.CA."+ LocalDate.now()))
                .itemCountLimitPerResource(2)
                .resourceSuffixCreator(index -> "-S1.V" + index+".K1.P1.data.csv")
                .build();
    }

    @Bean
    public ItemWriter<Employee> pythonDeveloperItemWriter() {
        FlatFileItemWriter<Employee> itemWriter = new FlatFileItemWriterBuilder<Employee>()
                .lineAggregator(new PassThroughLineAggregator<>())
                .name("itemsWriter")
                .build();

        return new MultiResourceItemWriterBuilder<Employee>()
                .name("pythonDeveloperItemWriter")
                .delegate(itemWriter)
                .resource(new FileSystemResource("AAA02.CPP.CA."+ LocalDate.now()))
                .itemCountLimitPerResource(2)
                .resourceSuffixCreator(index -> "-S1.V" + index+".K1.P1.data.csv")
                .build();
    }

    @Bean
    public ItemWriter<Employee> cloudDeveloperItemWriter() {
        FlatFileItemWriter<Employee> itemWriter = new FlatFileItemWriterBuilder<Employee>()
                .lineAggregator(new PassThroughLineAggregator<>())
                .name("itemsWriter")
                .build();

        return new MultiResourceItemWriterBuilder<Employee>()
                .name("cloudDeveloperItemWriter")
                .delegate(itemWriter)
                .resource(new FileSystemResource("AAA03.CPP.CA."+ LocalDate.now()))
                .itemCountLimitPerResource(2)
                .resourceSuffixCreator(index -> "-S1.V" + index+".K1.P1.data.csv")
                .build();
    }

    @Bean
    public Step step() throws Exception {
        return stepBuilderFactory.get("step")
                .<Employee, Employee>chunk(1)
                .reader(itemReader())
                .writer(classifierCompositeItemWriter())
                .build();
    }

    @Bean
    public Job job() throws Exception {
        return jobBuilderFactory.get("job")
                .start(step())
                .build();
    }
}

EmployeeClassifier.java

package com.example;

import org.springframework.batch.item.ItemWriter;
import org.springframework.classify.Classifier;

import lombok.Setter;


@Setter
public class EmployeeClassifier implements Classifier<Employee, ItemWriter<? super Employee>> {
    private static final long serialVersionUID = 1L;
    private ItemWriter<Employee> javaDeveloperFileItemWriter;
    private ItemWriter<Employee> pythonDeveloperFileItemWriter;
    private ItemWriter<Employee> cloudDeveloperFileItemWriter;
    
    public EmployeeClassifier() {
        
    }

    public EmployeeClassifier(ItemWriter<Employee> javaDeveloperFileItemWriter,
                              ItemWriter<Employee> pythonDeveloperFileItemWriter,
                              ItemWriter<Employee> cloudDeveloperFileItemWriter) {
        this.javaDeveloperFileItemWriter = javaDeveloperFileItemWriter;
        this.pythonDeveloperFileItemWriter = pythonDeveloperFileItemWriter;
        this.cloudDeveloperFileItemWriter = cloudDeveloperFileItemWriter;
    }

    @Override
    public ItemWriter<? super Employee> classify(Employee employee) {
        if(employee.getRole().equals("Java Developer")){
            return javaDeveloperFileItemWriter;
        }
        else if(employee.getRole().equals("Python Developer")){
            return pythonDeveloperFileItemWriter;
        }
        return cloudDeveloperFileItemWriter;
    }
}