Learn to read CSV file from filesystem or resources folder using FlatFileItemReader
class.
Table of Contents Project Structure Read CSV with FlatFileItemReader Write read rows to console Maven Dependency Demo
Project Structure
In this project, we will learn to –
- Read CSV file from
input/inputData.csv
. - Write data to console.

Read CSV with FlatFileItemReader
You need to use FlatFileItemReader
to read lines from CSV file.
@Bean public FlatFileItemReader<Employee> reader() { //Create reader instance FlatFileItemReader<Employee> reader = new FlatFileItemReader<Employee>(); //Set input file location reader.setResource(new FileSystemResource("input/inputData.csv")); //Set number of lines to skips. Use it if file has header rows. reader.setLinesToSkip(1); //Configure how each line will be parsed and mapped to different values reader.setLineMapper(new DefaultLineMapper() { { //3 columns in each row setLineTokenizer(new DelimitedLineTokenizer() { { setNames(new String[] { "id", "firstName", "lastName" }); } }); //Set values in Employee class setFieldSetMapper(new BeanWrapperFieldSetMapper<Employee>() { { setTargetType(Employee.class); } }); } }); return reader; }
id,firstName,lastName 1,Lokesh,Gupta 2,Amit,Mishra 3,Pankaj,Kumar 4,David,Miller
Write read rows to console
Create ConsoleItemWriter
class implementing ItemWriter
interface.
import java.util.List; import org.springframework.batch.item.ItemWriter; public class ConsoleItemWriter<T> implements ItemWriter<T> { @Override public void write(List<? extends T> items) throws Exception { for (T item : items) { System.out.println(item); } } }
Use ConsoleItemWriter
as writer.
@Bean public ConsoleItemWriter<Employee> writer() { return new ConsoleItemWriter<Employee>(); }
Maven Dependency
Look at project dependencies.
<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.howtodoinjava</groupId> <artifactId>App</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>App</name> <url>http://maven.apache.org</url> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.3.RELEASE</version> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-batch</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> <repositories> <repository> <id>repository.spring.release</id> <name>Spring GA Repository</name> <url>http://repo.spring.io/release</url> </repository> </repositories> </project>
Demo
Before running the application, look at complete code of BatchConfig.java
.
package com.howtodoinjava.demo.config; 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.launch.support.RunIdIncrementer; import org.springframework.batch.item.file.FlatFileItemReader; 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.FileSystemResource; import com.howtodoinjava.demo.model.Employee; @Configuration @EnableBatchProcessing public class BatchConfig { @Autowired private JobBuilderFactory jobBuilderFactory; @Autowired private StepBuilderFactory stepBuilderFactory; @Bean public Job readCSVFilesJob() { return jobBuilderFactory .get("readCSVFilesJob") .incrementer(new RunIdIncrementer()) .start(step1()) .build(); } @Bean public Step step1() { return stepBuilderFactory.get("step1").<Employee, Employee>chunk(5) .reader(reader()) .writer(writer()) .build(); } @SuppressWarnings({ "rawtypes", "unchecked" }) @Bean public FlatFileItemReader<Employee> reader() { //Create reader instance FlatFileItemReader<Employee> reader = new FlatFileItemReader<Employee>(); //Set input file location reader.setResource(new FileSystemResource("input/inputData.csv")); //Set number of lines to skips. Use it if file has header rows. reader.setLinesToSkip(1); //Configure how each line will be parsed and mapped to different values reader.setLineMapper(new DefaultLineMapper() { { //3 columns in each row setLineTokenizer(new DelimitedLineTokenizer() { { setNames(new String[] { "id", "firstName", "lastName" }); } }); //Set values in Employee class setFieldSetMapper(new BeanWrapperFieldSetMapper<Employee>() { { setTargetType(Employee.class); } }); } }); return reader; } @Bean public ConsoleItemWriter<Employee> writer() { return new ConsoleItemWriter<Employee>(); } }
public class Employee { String id; String firstName; String lastName; //public setter and getter methods }
package com.howtodoinjava.demo; import org.springframework.batch.core.Job; import org.springframework.batch.core.JobParameters; import org.springframework.batch.core.JobParametersBuilder; import org.springframework.batch.core.launch.JobLauncher; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.scheduling.annotation.EnableScheduling; import org.springframework.scheduling.annotation.Scheduled; @SpringBootApplication @EnableScheduling public class App { @Autowired JobLauncher jobLauncher; @Autowired Job job; public static void main(String[] args) { SpringApplication.run(App.class, args); } @Scheduled(cron = "0 */1 * * * ?") public void perform() throws Exception { JobParameters params = new JobParametersBuilder() .addString("JobID", String.valueOf(System.currentTimeMillis())) .toJobParameters(); jobLauncher.run(job, params); } }
#Disable batch job's auto start spring.batch.job.enabled=false spring.main.banner-mode=off
Run the application
Run the application as Spring boot application, and watch the console. Batch job will start at start of each minute. It will read the input file, and print the read values in console.
2018-07-10 13:28:35 INFO - Starting App on FFC15B4E9C5AA with PID 12060 (C:\Users\user\app\App\target\classes started by zkpkhua in C:\Users\user\app\App) 2018-07-10 13:28:35 INFO - No active profile set, falling back to default profiles: default 2018-07-10 13:28:35 INFO - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@75329a49: startup date [Tue Jul 10 13:28:35 IST 2018]; root of context hierarchy 2018-07-10 13:28:37 INFO - HikariPool-1 - Starting... 2018-07-10 13:28:38 INFO - HikariPool-1 - Start completed. 2018-07-10 13:28:38 INFO - No database type set, using meta data indicating: H2 2018-07-10 13:28:38 INFO - No TaskExecutor has been set, defaulting to synchronous executor. 2018-07-10 13:28:39 INFO - Executing SQL script from class path resource [org/springframework/batch/core/schema-h2.sql] 2018-07-10 13:28:39 INFO - Executed SQL script from class path resource [org/springframework/batch/core/schema-h2.sql] in 74 ms. 2018-07-10 13:28:39 INFO - Registering beans for JMX exposure on startup 2018-07-10 13:28:39 INFO - Bean with name 'dataSource' has been autodetected for JMX exposure 2018-07-10 13:28:39 INFO - Located MBean 'dataSource': registering with JMX server as MBean [com.zaxxer.hikari:name=dataSource,type=HikariDataSource] 2018-07-10 13:28:39 INFO - No TaskScheduler/ScheduledExecutorService bean found for scheduled processing 2018-07-10 13:28:39 INFO - Started App in 4.485 seconds (JVM running for 5.33) 2018-07-10 13:29:00 INFO - Job: [SimpleJob: [name=readCSVFilesJob]] launched with the following parameters: [{JobID=1531209540004}] 2018-07-10 13:29:00 INFO - Executing step: [step1] Employee [id=1, firstName=Lokesh, lastName=Gupta] Employee [id=2, firstName=Amit, lastName=Mishra] Employee [id=3, firstName=Pankaj, lastName=Kumar] Employee [id=4, firstName=David, lastName=Miller] 2018-07-10 13:29:00 INFO - Job: [SimpleJob: [name=readCSVFilesJob]] completed with the following parameters: [{JobID=1531209540004}] and the following status: [COMPLETED]
Drop me your questions in comments section.
Happy Learning !!
David Fanjkutic
this does not work for CSV records that are multi-line
Amith
How can the above code be enhanced to validate the inputs. Lets assume firstname and lastname can be of size max 5 length. How can the code be modified to include the constraints along with exception handling
Sweety
Hi I am new to Java can you please tell me what chnages required for Postgres DB
chaimae
when im trying to run the project i got this error :
PLICATION FAILED TO START
***************************
Description:
Field jobLauncher in com.example.demo.App required a bean of type ‘org.springframework.batch.core.launch.JobLauncher’ that could not be found.
The injection point has the following annotations:
– @org.springframework.beans.factory.annotation.Autowired(required=true)
Action:
Consider defining a bean of type ‘org.springframework.batch.core.launch.JobLauncher’ in your configuration.
Dhruv
Hi chaimae,
You got resolved this issue? I am having same issue.
Thanks
govind
i am not able ad new files in the directory . reader doesn’t read the record from the directory which newly added .
Priyanka Sinha
Hi,
I am working on spring application. I am reading csv or excel file with very large dataset. Please provide me some reference for this using spring batch and printing to console for Spring application, not SpringBoot app. Above given example is for SpringBoot application.
I have written BatchConfig and console writer classes. I am not able to test it as App class mentioned above is for springboot application, not for spring. Could you please help me in writing App class for spring application and testing it?
Thanks in advance.
Priyanka Sinha
Please provide me some reference for reading csv or excel file using spring batch and printing to console for Spring application, not SpringBoot app. Above given example is for SpringBoot application.
Thanks in advance.