Spring Batch FlatFileItemReader Example

March 24, 2022

In this tutorial, we will see Spring Batch FlatFileItemReader Example. We will read data from an excel file and store it in the database using FlatFileItemReader. The FlatFileItemReader is used to reads lines from the input resources. We are going to use the MySql database.

flatFileItemReader.setResource(new ClassPathResource("data.csv"))

Configure FlatFileItemReader class

@EnableBatchProcessing
@Configuration
public class SpringBatchConfig {

    @Autowired
    private DataSource dataSource;

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    public FlatFileItemReader<Student> reader() {
        FlatFileItemReader<Student> itemReader = new FlatFileItemReader<>();
        itemReader.setResource(new ClassPathResource("data.csv"));
        itemReader.setLineMapper(getLineMapper());
        itemReader.setLinesToSkip(1);
        return itemReader;
    }

    private LineMapper<Student> getLineMapper() {
        DefaultLineMapper<Student> lineMapper = new DefaultLineMapper<>();
        DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();

        String[] columnsToBeInserted = new String[]{"id", "roll_number", "name"};
        int[] fields = new int[]{0, 1, 2};
        tokenizer.setNames(columnsToBeInserted);
        tokenizer.setIncludedFields(fields);
        BeanWrapperFieldSetMapper<Student> fieldSetMapper = new BeanWrapperFieldSetMapper<>();
        fieldSetMapper.setTargetType(Student.class);
        lineMapper.setLineTokenizer(tokenizer);
        lineMapper.setFieldSetMapper(fieldSetMapper);
        return lineMapper;
    }

    @Bean
    public StudentItemProcessor processor() {
        return new StudentItemProcessor();
    }

    @Bean
    public JdbcBatchItemWriter<Student> writer() {
        JdbcBatchItemWriter<Student> writer = new JdbcBatchItemWriter<>();
        writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<>());
        writer.setSql("insert into student(id,roll_number,name) values (:id,:rollNumber,:name)");
        writer.setDataSource(dataSource);
        return writer;
    }


    @Bean
    public Job writeStudentDataIntoSqlDb() {
        JobBuilder jobBuilder = jobBuilderFactory.get("STUDENT_JOB");
        jobBuilder.incrementer(new RunIdIncrementer());
        FlowJobBuilder flowJobBuilder = jobBuilder.flow(getFirstStep()).end();
        Job job = flowJobBuilder.build();
        return job;
    }

    @Bean
    public Step getFirstStep() {
        StepBuilder stepBuilder = stepBuilderFactory.get("getFirstStep");
        SimpleStepBuilder<Student, Student> simpleStepBuilder = stepBuilder.chunk(1);
        return simpleStepBuilder.reader(reader()).processor(processor()).writer(writer()).build();
    }

}

The FlatFileItemReader uses DefaultLineMapper that further uses LineTokenizer and FieldSetMapper. The FlatFileItemReader also uses RecordSeparatorPolicy.

We are using javax.sql.DataSource interface to get datasource. The JobBuilderFactory used to get JobBuilder.

Let’s see Spring Batch FlatFileItemReader Example from scratch.

maven dependency

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.javatute.com</groupId>
    <artifactId>springbatch</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.1.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.batch</groupId>
            <artifactId>spring-batch-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-batch</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

</project>

Directory structure

Define Student.java

package com.springbatchexample.entity;

public class Student {

    private Long id;
    private String name;
    private String rollNumber;

    public Student() {

    }

    public Student(Long id, String name, String rollNumber) {
        this.id = id;
        this.name = name;
        this.rollNumber = rollNumber;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getRollNumber() {
        return rollNumber;
    }

    public void setRollNumber(String rollNumber) {
        this.rollNumber = rollNumber;
    }

}

Define StudentItemProcessor

package com.springbatchexample.config;

import com.springbatchexample.entity.Student;
import org.springframework.batch.item.ItemProcessor;

public class StudentItemProcessor implements ItemProcessor<Student, Student> {

    @Override
    public Student process(Student student) throws Exception {
        return student;
    }
}

Define SpringBatchConfig file

package com.springbatchexample.config;

import com.springbatchexample.entity.Student;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.job.builder.FlowJobBuilder;
import org.springframework.batch.core.job.builder.JobBuilder;
import org.springframework.batch.core.launch.support.RunIdIncrementer;
import org.springframework.batch.core.step.builder.SimpleStepBuilder;
import org.springframework.batch.core.step.builder.StepBuilder;
import org.springframework.batch.item.database.BeanPropertyItemSqlParameterSourceProvider;
import org.springframework.batch.item.database.JdbcBatchItemWriter;
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.LineMapper;
import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper;
import org.springframework.batch.item.file.mapping.DefaultLineMapper;
import org.springframework.batch.item.file.transform.DelimitedLineTokenizer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;

import javax.sql.DataSource;

@EnableBatchProcessing
@Configuration
public class SpringBatchConfig {


    @Autowired
    private DataSource dataSource;

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    public FlatFileItemReader<Student> reader() {
        FlatFileItemReader<Student> itemReader = new FlatFileItemReader<>();
        itemReader.setResource(new ClassPathResource("data.csv"));
        itemReader.setLineMapper(getLineMapper());
        itemReader.setLinesToSkip(1);
        return itemReader;

    }

    private LineMapper<Student> getLineMapper() {
        DefaultLineMapper<Student> lineMapper = new DefaultLineMapper<>();
        DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();

        String[] columnsToBeInserted = new String[]{"id", "roll_number", "name"};
        int[] fields = new int[]{0, 1, 2};
        tokenizer.setNames(columnsToBeInserted);
        tokenizer.setIncludedFields(fields);
        BeanWrapperFieldSetMapper<Student> fieldSetMapper = new BeanWrapperFieldSetMapper<>();
        fieldSetMapper.setTargetType(Student.class);
        lineMapper.setLineTokenizer(tokenizer);
        lineMapper.setFieldSetMapper(fieldSetMapper);
        return lineMapper;
    }

    @Bean
    public StudentItemProcessor processor() {
        return new StudentItemProcessor();
    }

    @Bean
    public JdbcBatchItemWriter<Student> writer() {
        JdbcBatchItemWriter<Student> writer = new JdbcBatchItemWriter<>();
        writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<>());
        writer.setSql("insert into student(id,roll_number,name) values (:id,:rollNumber,:name)");
        writer.setDataSource(dataSource);
        return writer;
    }

    @Bean
    public Job writeStudentDataIntoSqlDb() {
        JobBuilder jobBuilder = jobBuilderFactory.get("STUDENT_JOB");
        jobBuilder.incrementer(new RunIdIncrementer());
        FlowJobBuilder flowJobBuilder = jobBuilder.flow(getFirstStep()).end();
        Job job = flowJobBuilder.build();
        return job;
    }

    @Bean
    public Step getFirstStep() {
        StepBuilder stepBuilder = stepBuilderFactory.get("getFirstStep");
        SimpleStepBuilder<Student, Student> simpleStepBuilder = stepBuilder.chunk(1);
        return simpleStepBuilder.reader(reader()).processor(processor()).writer(writer()).build();
    }
}

Define SpringMain.java

package com.springbatchexample.main;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan(basePackages = "com.springbatchexample.*")
public class SpringMain {
    public static void main(String[] args) {

        SpringApplication.run(SpringMain.class, args);
    }
}

application.properties file

spring.datasource.url=jdbc:mysql://localhost:3306/springbootdb
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.hibernate.ddl-auto=create
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
server.port = 9091
spring.batch.initialize-schema=always

id,roll_number,name
1,0126,Daenerys
2,0127,Bran
3,0128,Sam
4,0129,Eddard
5,0130,Jon
6,0131,Cersei
7,0132,Tyrion
8,0133,Sansa
9,0134,Arya
10,0135,Jaime

Run the and verify the db

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