Step-by-Step Guide: Creating a Simple Spring Batch Application in Eclipse

Step 1: Project Setup

Create a new Maven project in Eclipse and add the following dependencies to your pom.xml file:

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-batch</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
</dependencies>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-batch</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-data-jpa</artifactId>

</dependency>

</dependencies>

Step 2: Configure Batch

Create a configuration class (BatchConfiguration.java) to set up Spring Batch:

import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.item.ItemReader;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;
import org.springframework.batch.item.file.transform.DelimitedLineTokenizer;
import org.springframework.batch.item.file.transform.FieldSet;
import org.springframework.batch.item.file.transform.LineTokenizer;
import org.springframework.batch.item.file.mapping.FieldSetMapper;
import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper;
import org.springframework.batch.item.file.mapping.DefaultLineMapper;
import org.springframework.batch.item.file.separator.DefaultRecordSeparatorPolicy;

@Configuration
@EnableBatchProcessing
public class BatchConfiguration {

    @Bean
    public Job myJob(Step myStep) {
        return jobBuilderFactory.get("myJob")
                .start(myStep)
                .build();
    }

    @Bean
    public Step myStep(ItemReader<MyInputData> reader,
                       ItemProcessor<MyInputData, MyOutputData> processor,
                       ItemWriter<MyOutputData> writer) {
        return stepBuilderFactory.get("myStep")
                .<MyInputData, MyOutputData>chunk(10)
                .reader(reader)
                .processor(processor)
                .writer(writer)
                .build();
    }

    @Bean
    public FlatFileItemReader<MyInputData> reader() {
        return new FlatFileItemReaderBuilder<MyInputData>()
                .name("myItemReader")
                .resource(new ClassPathResource("input.csv"))
                .lineTokenizer(lineTokenizer())
                .fieldSetMapper(new BeanWrapperFieldSetMapper<MyInputData>() {{
                    setTargetType(MyInputData.class);
                }})
                .build();
    }

    @Bean
    public LineTokenizer lineTokenizer() {
        DelimitedLineTokenizer lineTokenizer = new DelimitedLineTokenizer();
        lineTokenizer.setNames("id", "name", "age");
        lineTokenizer.setDelimiter(",");
        return lineTokenizer;
    }

    @Bean
    public ItemProcessor<MyInputData, MyOutputData> processor() {
        return new MyItemProcessor();
    }

    @Bean
    public ItemWriter<MyOutputData> writer() {
        return items -> {
            for (MyOutputData item : items) {
                System.out.println("Writing item: " + item);
            }
        };
    }
}

import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.batch.core.Job;

import org.springframework.batch.core.Step;

import org.springframework.batch.item.ItemReader;

import org.springframework.batch.item.ItemWriter;

import org.springframework.batch.item.file.FlatFileItemReader;

import org.springframework.batch.item.file.builder.FlatFileItemReaderBuilder;

import org.springframework.batch.item.file.transform.DelimitedLineTokenizer;

import org.springframework.batch.item.file.transform.FieldSet;

import org.springframework.batch.item.file.transform.LineTokenizer;

import org.springframework.batch.item.file.mapping.FieldSetMapper;

import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper;

import org.springframework.batch.item.file.mapping.DefaultLineMapper;

import org.springframework.batch.item.file.separator.DefaultRecordSeparatorPolicy;

@Configuration

@EnableBatchProcessing

public class BatchConfiguration {

@Bean

public Job myJob(Step myStep) {

return jobBuilderFactory.get("myJob")

.start(myStep)

.build();

}

@Bean

public Step myStep(ItemReader<MyInputData> reader,

ItemProcessor<MyInputData, MyOutputData> processor,

ItemWriter<MyOutputData> writer) {

return stepBuilderFactory.get("myStep")

.<MyInputData, MyOutputData>chunk(10)

.reader(reader)

.processor(processor)

.writer(writer)

.build();

}

@Bean

public FlatFileItemReader<MyInputData> reader() {

return new FlatFileItemReaderBuilder<MyInputData>()

.name("myItemReader")

.resource(new ClassPathResource("input.csv"))

.lineTokenizer(lineTokenizer())

.fieldSetMapper(new BeanWrapperFieldSetMapper<MyInputData>() {{

setTargetType(MyInputData.class);

}})

.build();

}

@Bean

public LineTokenizer lineTokenizer() {

DelimitedLineTokenizer lineTokenizer = new DelimitedLineTokenizer();

lineTokenizer.setNames("id", "name", "age");

lineTokenizer.setDelimiter(",");

return lineTokenizer;

}

@Bean

public ItemProcessor<MyInputData, MyOutputData> processor() {

return new MyItemProcessor();

}

@Bean

public ItemWriter<MyOutputData> writer() {

return items -> {

for (MyOutputData item : items) {

System.out.println("Writing item: " + item);

}

};

}

Step 3: Input and Output Classes

Create input and output classes (MyInputData.java and MyOutputData.java) to represent the data read from the input file and the processed data to be written:

public class MyInputData {
    private Long id;
    private String name;
    private int age;

    // Getters and setters
}

public class MyOutputData {
    private Long id;
    private String processedName;
    private int doubledAge;

    // Getters and setters
}

public class MyInputData {

private Long id;

private String name;

private int age;

// Getters and setters

}

public class MyOutputData {

private Long id;

private String processedName;

private int doubledAge;

// Getters and setters

}

Step 4: Processor

Implement the ItemProcessor interface (MyItemProcessor.java) to define the processing logic:

public class MyItemProcessor implements ItemProcessor<MyInputData, MyOutputData> {

    @Override
    public MyOutputData process(MyInputData item) throws Exception {
        MyOutputData processedData = new MyOutputData();
        processedData.setId(item.getId());
        processedData.setProcessedName(item.getName().toUpperCase());
        processedData.setDoubledAge(item.getAge() * 2);
        return processedData;
    }
}

public class MyItemProcessor implements ItemProcessor<MyInputData, MyOutputData> {

@Override

public MyOutputData process(MyInputData item) throws Exception {

MyOutputData processedData = new MyOutputData();

processedData.setId(item.getId());

processedData.setProcessedName(item.getName().toUpperCase());

processedData.setDoubledAge(item.getAge() * 2);

return processedData;

}

Step 5: Input CSV File

Create a CSV file (input.csv) with sample data:

id,name,age
1,John,25
2,Jane,30
3,Bob,22

id,name,age

1,John,25

2,Jane,30

3,Bob,22

Step 6: Run the Application

Create a main class (BatchApplication.java) to run the application:

@SpringBootApplication
public class BatchApplication {

    public static void main(String[] args) {
        SpringApplication.run(BatchApplication.class, args);
    }
}

@SpringBootApplication

public class BatchApplication {