Spring Batch provides the Tasklet interface, to process a single task, such as clean or init resources before or after any step running. In the tutorial, JavaSampleApproach will guide you how to use Spring Batch Tasklet.
Related Posts:
– How to start with Spring Batch using Spring Boot – Java Config
– Spring Batch XML Config by Spring Boot
– Spring Batch Job with Parallel Steps
– Spring Batch – Programmatic Flow Decision
– How to import CSV data to PostgreSQL Database using Spring Batch Job
– Spring XD Option Module – Batch Job with PostgreSQL Datasource
– How to use Spring Batch Restartable Function
Contents
I. Technologies
– Java 1.8
– Maven 3.3.9
– Spring Boot: 1.4.3.RELEASE
– Spring Tool Suite – Version 3.8.1.RELEASE
II. Overview
1. Project Structure
In the tutorial, we create a Job with 2 step:step1 -> step 2.
step1 processes a file C:\\readfile\\1.txt.
step2 is used to delete the file after processing by step1. So step2 is implemented by Tasklet.
2. Step to do
– Create Spring Boot project
– Implement Reader & Writer for step1
– Implement Tasklet for step2
– Config a Batch Job
– Implement JobLauncherController
– Run & Enjoy Results
III. Practice
1. Create Spring Boot project
– Open Spring Tool Suite, on main menu, choose File->New->Spring Starter Project, input project info. Press Next then Finish, a Spring Boot project will be created successfully.
Add needed dependencies:
– spring-boot-starter-web
– spring-boot-starter-batch
– postgresql
Details:
<?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.javasampleapproach.springbatch</groupId> <artifactId>SpringBatchTasklet</artifactId> <version>0.0.1</version> <packaging>jar</packaging> <name>SpringBatchTasklet</name> <description>SpringBatchTasklet</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.1.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-batch</artifactId> </dependency> <!-- http://mvnrepository.com/artifact/postgresql/postgresql --> <dependency> <groupId>postgresql</groupId> <artifactId>postgresql</artifactId> <version>9.1-901-1.jdbc4</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> |
2. Implement Reader & Write for step1
– Implement Reader:
package com.javasampleapproach.springbatch.step; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.batch.item.ItemReader; import org.springframework.batch.item.NonTransientResourceException; import org.springframework.batch.item.ParseException; import org.springframework.batch.item.UnexpectedInputException; public class Reader implements ItemReader<String>{ private String[] files = {"C:\\readfile\\1.txt"}; public int count=0; Logger logger = LoggerFactory.getLogger(this.getClass()); @Override public String read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException { if(count < files.length){ return files[count++]; }else{ count=0; } return null; } } |
– Implement Writer:
package com.javasampleapproach.springbatch.step; import java.io.IOException; import java.nio.file.Files; import java.nio.file.Paths; import java.util.List; import java.util.stream.Stream; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.batch.item.ItemWriter; public class Writer implements ItemWriter<String> { Logger logger = LoggerFactory.getLogger(this.getClass()); @Override public void write(List<? extends String> paths) throws Exception { for(String filePath : paths){ System.out.println("filePath = " + filePath); try (Stream<String> stream = Files.lines(Paths.get(filePath))) { stream.forEach(System.out::println); } catch (IOException e) { throw(e); } } } } |
3. Implement Tasklet for step2
Create TaskletStep by implement: Tasklet interface. TaskletStep just deletes a file: C:\\readfile\\1.txt after step1‘s processing
package com.javasampleapproach.springbatch.tasklet; import java.io.File; 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; import org.springframework.stereotype.Component; @Component public class TaskletStep implements Tasklet{ @Override public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception { try{ File file = new File("C:\\readfile\\1.txt"); if(file.delete()){ System.out.println("### TaskletStep:" + file.getName() + " is deleted!"); }else{ System.out.println("Delete operation is failed."); } }catch(Exception e){ e.printStackTrace(); } return null; } } |
4. Config a Batch Job
Configure a Job with 2 step: step1->step2.
package com.javasampleapproach.springbatch.config; 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.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.javasampleapproach.springbatch.step.Reader; import com.javasampleapproach.springbatch.step.Writer; import com.javasampleapproach.springbatch.tasklet.TaskletStep; @Configuration public class BatchConfig { @Autowired TaskletStep taskletStep; @Autowired public JobBuilderFactory jobBuilderFactory; @Autowired public StepBuilderFactory stepBuilderFactory; @Bean public Job job() { return jobBuilderFactory.get("job") .incrementer(new RunIdIncrementer()) .start(step1()).next(step2()) .build(); } @Bean public Step step1() { return stepBuilderFactory.get("step1") .<String, String> chunk(1) .reader(new Reader()) .writer(new Writer()) .build(); } @Bean public Step step2() { return stepBuilderFactory.get("step2") .tasklet(taskletStep) .build(); } } |
5. Implement JobLauncherController
Implement JobLauncherController
package com.javasampleapproach.springbatch.controller; import org.slf4j.Logger; import org.slf4j.LoggerFactory; 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.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class JobLauncherController { @Autowired JobLauncher jobLauncher; @Autowired Job job; @RequestMapping("/launchjob") public String handle() throws Exception { Logger logger = LoggerFactory.getLogger(this.getClass()); try { JobParameters jobParameters = new JobParametersBuilder().addLong("time", System.currentTimeMillis()) .toJobParameters(); jobLauncher.run(job, jobParameters); } catch (Exception e) { logger.info(e.getMessage()); } return "Done!"; } } |
6. Run & Enjoy Results
Build & Run the project with Spring Boot App mode.
Launch the Job by a request:
http://localhost:8080/launchjob
Logs:
Job: [SimpleJob: [name=job]] launched with the following parameters: [{time=1486471748444}] o.s.batch.core.job.SimpleStepHandler : Executing step: [step1] filePath = C:\readfile\1.txt line1 line2 line3 line4 line5 o.s.batch.core.job.SimpleStepHandler : Executing step: [step2] ### TaskletStep:1.txt is deleted! o.s.b.c.l.support.SimpleJobLauncher : Job: [SimpleJob: [name=job]] completed with the following parameters: [{time=1486471748444}] and the following status: [COMPLETED] |
IV. Sourcecode
Last updated on June 4, 2017.