Batch Service is a process to execute more than one command in a single task.
In this chapter, we are going to learn how to create batch service in a Spring Boot application.
Let us consider an example where we are going to save the CSV file content into HSQLDB.
To create a Batch Service program, we need to add the Spring Boot Starter Batch dependency and HSQLDB dependency in our build configuration file.
Step 1. Maven users can add the following dependencies in pom.xml file.
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-batch</artifactId>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
</dependency>
Gradle users can add the following dependencies in build.gradle file.
compile("org.hsqldb:hsqldb")
Now, add the simple CSV data file under classpath resources – src/main/resources and name the file as file.csv as shown −
Mike, Sebastian
Lawarance, Lime
Step 2. Next, write a SQL script for HSQLDB – under the classpath resource directory – request_fail_hystrix_timeout
CREATE TABLE USERS (
user_id BIGINT IDENTITY NOT NULL PRIMARY KEY,
first_name VARCHAR(20),
last_name VARCHAR(20)
);
Step 3. Create a POJO class for USERS model as shown −
public class User {
private String lastName;
private String firstName;
public User() {
}
public User(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Override
public String toString() {
return "firstName: " + firstName + ", lastName: " + lastName;
}
}
Step 4. Now, create an intermediate processor to do the operations after the reading the data from the CSV file and before writing the data into SQL.
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.batch.item.ItemProcessor;
public class UserItemProcessor implements ItemProcessor<User, User> {
private static final Logger log = LoggerFactory.getLogger(UserItemProcessor.class);
@Override
public User process(final User user) throws Exception {
final String firstName = user.getFirstName().toUpperCase();
final String lastName = user.getLastName().toUpperCase();
final User transformedPerson = new User(firstName, lastName);
log.info("Converting (" + user + ") into (" + transformedPerson + ")");
return transformedPerson;
}
}
Step 5. Let us create a Batch configuration file, to read the data from CSV and write into the SQL file as shown below. We need to add the @EnableBatchProcessing annotation in the configuration class file. The @EnableBatchProcessing annotation is used to enable the batch operations for your Spring Boot application.
import javax.sql.DataSource;
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.database.BeanPropertyItemSqlParameterSourceProvider;
import org.springframework.batch.item.database.JdbcBatchItemWriter;
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.ClassPathResource;
@Configuration
@EnableBatchProcessing
public class BatchConfiguration {
@Autowired
public JobBuilderFactory jobBuilderFactory;
@Autowired
public StepBuilderFactory stepBuilderFactory;
@Autowired
public DataSource dataSource;
@Bean
public FlatFileItemReader<User> reader() {
FlatFileItemReader<User> reader = new FlatFileItemReader<User>();
reader.setResource(new ClassPathResource("file.csv"));
reader.setLineMapper(new DefaultLineMapper<User>() {
{
setLineTokenizer(new DelimitedLineTokenizer() {
{
setNames(new String[] { "firstName", "lastName" });
}
});
setFieldSetMapper(new BeanWrapperFieldSetMapper<User>() {
{
setTargetType(User.class);
}
});
}
});
return reader;
}
@Bean
public UserItemProcessor processor() {
return new UserItemProcessor();
}
@Bean
public JdbcBatchItemWriter<User> writer() {
JdbcBatchItemWriter<User> writer = new JdbcBatchItemWriter<User>();
writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<User>());
writer.setSql("INSERT INTO USERS (first_name, last_name) VALUES (:firstName, :lastName)");
writer.setDataSource(dataSource);
return writer;
}
@Bean
public Job importUserJob(JobCompletionNotificationListener listener) {
return jobBuilderFactory.get("importUserJob").incrementer(
new RunIdIncrementer()).listener(listener).flow(step1()).end().build();
}
@Bean
public Step step1() {
return stepBuilderFactory.get("step1").<User, User>chunk(10).reader(reader()).processor(processor()).writer(writer()).build();
}
}
The reader() method is used to read the data from the CSV file and writer() method is used to write a data into the SQL.
Step 6. Next, we will have to write a Job Completion Notification Listener class – used to notify after the Job completion.
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.batch.core.BatchStatus;
import org.springframework.batch.core.JobExecution;
import org.springframework.batch.core.listener.JobExecutionListenerSupport;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Component;
@Component
public class JobCompletionNotificationListener extends JobExecutionListenerSupport {
private static final Logger log = LoggerFactory.getLogger(JobCompletionNotificationListener.class);
private final JdbcTemplate jdbcTemplate;
@Autowired
public JobCompletionNotificationListener(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
@Override
public void afterJob(JobExecution jobExecution) {
if (jobExecution.getStatus() == BatchStatus.COMPLETED) {
log.info("!!! JOB FINISHED !! It's time to verify the results!!");
List<User> results = jdbcTemplate.query(
"SELECT first_name, last_name FROM USERS", new RowMapper<User>() {
@Override
public User mapRow(ResultSet rs, int row) throws SQLException {
return new User(rs.getString(1), rs.getString(2));
}
});
for (User person : results) {
log.info("Found <" + person + "> in the database.");
}
}
}
}
Step 7. Now, create an executable JAR file, and run the Spring Boot application by using the following Maven or Gradle commands.
For Maven, use the command as shown −
mvn clean install
After “BUILD SUCCESS”, you can find the JAR file under the target directory.
For Gradle, you can use the command as shown −
gradle clean build
After “BUILD SUCCESSFUL”, you can find the JAR file under the build/libs directory.
Run the JAR file by using the command given here −
java –jar <JARFILE>
You can see the output in console window as shown −
