Spring Batch Example

Learn to create Spring batch job (with multiple steps) with Java configuration. It uses Spring Boot 2, Spring batch 4 and H2 database to execute batch job.

Table of Contents

Project Structure
Maven Dependencies
Add Tasklets
Spring Batch Configuration
Demo

Project Structure

In this project, we will create a simple job with 2 step tasks and execute the job to observe the logs. Job execution flow will be –

1. Start job
2. Execute task one
3. Execute task two
4. Finish job

Spring Batch Java Config Example

Maven Dependencies

We need to include spring-boot-starter-batch dependency. Spring batch relies on job repository which is persistent data store. So we need one DB as well. I am using H2 (in-memory database) which integrates well with spring batch.

pom.xml

<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>

Add Tasklets

The first step is to create few tasks which will be run in some sequence to form a job. In Spring batch, they are implemented as Tasklet.

MyTaskOne.java

import org.springframework.batch.core.StepContribution; import org.springframework.batch.core.scope.context.ChunkContext; import org.springframework.batch.core.step.tasklet.Tasklet; import org.springframework.batch.repeat.RepeatStatus; public class MyTaskOne implements Tasklet {     public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception     {         System.out.println("MyTaskOne start..");         // ... your code                   System.out.println("MyTaskOne done..");         return RepeatStatus.FINISHED;     }    }

MyTaskTwo.java

import org.springframework.batch.core.StepContribution; import org.springframework.batch.core.scope.context.ChunkContext; import org.springframework.batch.core.step.tasklet.Tasklet; import org.springframework.batch.repeat.RepeatStatus; public class MyTaskTwo implements Tasklet {     public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception     {         System.out.println("MyTaskTwo start..");         // ... your code                   System.out.println("MyTaskTwo done..");         return RepeatStatus.FINISHED;     }    }

Spring Batch Configuration

This is major step where you define all the job related configurations and it’s execution logic.

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.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import com.howtodoinjava.demo.tasks.MyTaskOne; import com.howtodoinjava.demo.tasks.MyTaskTwo; @Configuration @EnableBatchProcessing public class BatchConfig {           @Autowired     private JobBuilderFactory jobs;     @Autowired     private StepBuilderFactory steps;           @Bean     public Step stepOne(){         return steps.get("stepOne")                 .tasklet(new MyTaskOne())                 .build();     }           @Bean     public Step stepTwo(){         return steps.get("stepTwo")                 .tasklet(new MyTaskTwo())                 .build();     }             @Bean     public Job demoJob(){         return jobs.get("demoJob")                 .incrementer(new RunIdIncrementer())                 .start(stepOne())                 .next(stepTwo())                 .build();     } }

Demo

Now our simple job 'demoJob' is configured and ready to be executed. I am using CommandLineRunner interface to execute the job automatically, with JobLauncher, when the application is fully started.

App.java

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.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class App implements CommandLineRunner {     @Autowired     JobLauncher jobLauncher;           @Autowired     Job job;           public static void main(String[] args)     {         SpringApplication.run(App.class, args);     }     @Override     public void run(String... args) throws Exception     {         JobParameters params = new JobParametersBuilder()                     .addString("JobID", String.valueOf(System.currentTimeMillis()))                     .toJobParameters();         jobLauncher.run(job, params);     } }

Notice the console logs.

Console Logs

o.s.b.c.l.support.SimpleJobLauncher      : Job: [SimpleJob: [name=demoJob]] launched with the following parameters: [{JobID=1530697766768}] o.s.batch.core.job.SimpleStepHandler     : Executing step: [stepOne] MyTaskOne start.. MyTaskOne done.. o.s.batch.core.job.SimpleStepHandler     : Executing step: [stepTwo] MyTaskTwo start.. MyTaskTwo done.. o.s.b.c.l.support.SimpleJobLauncher      : Job: [SimpleJob: [name=demoJob]] completed with the following parameters: [{JobID=1530697766768}] and the following status: [COMPLETED]

Spring also automatically run batch jobs configured. To disable auto-run of jobs, you need to use spring.batch.job.enabled property in application.properties file.

application.properties

spring.batch.job.enabled=false

Reference:

• HowToDoInJava.com - Spring Batch Multiple Steps
• StackOverflow - Spring Batch - Running Specific Job using @Qualifier
• StackOverflow - Spring Batch - Auto Create / Initialize Batch Table
• StackOverflow - Spring Batch - Get Parameter Inside Step