# Spring Batch
- Spring Boot runs `schema-@@platform@@.sql` automatically during startup.
- `-all` is the default for all platforms.

## schema-all.sql

```sql
DROP TABLE people IF EXISTS;

CREATE TABLE people  (
    person_id BIGINT IDENTITY NOT NULL PRIMARY KEY,
    first_name VARCHAR(20),
    last_name VARCHAR(20)
);
```

```
Jill,Doe
Joe,Doe
Justin,Doe
Jane,Doe
John,Doe
```

## Dependency

```groovy
	implementation 'org.springframework.boot:spring-boot-starter-batch'
	runtimeOnly 'org.hsqldb:hsqldb'
```

## Code
- Intermediate Processor

```java
import org.springframework.batch.item.ItemProcessor;

public class PersonItemProcessor implements ItemProcessor<Person, Person> {
}
```

- Batch Job

```java
@Configuration
@EnableBatchProcessing
public class BatchConfiguration {

  @Autowired
  public JobBuilderFactory jobBuilderFactory;

  @Autowired
  public StepBuilderFactory stepBuilderFactory;

    ...

}
```

```java
@Bean
public FlatFileItemReader<Person> reader() {
  return new FlatFileItemReaderBuilder<Person>()
    .name("personItemReader")
    .resource(new ClassPathResource("sample-data.csv"))
    .delimited()
    .names(new String[]{"firstName", "lastName"})
    .fieldSetMapper(new BeanWrapperFieldSetMapper<Person>() {{
      setTargetType(Person.class);
    }})
    .build();
}

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

@Bean
public JdbcBatchItemWriter<Person> writer(DataSource dataSource) {
  return new JdbcBatchItemWriterBuilder<Person>()
    .itemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<>())
    .sql("INSERT INTO people (first_name, last_name) VALUES (:firstName, :lastName)")
    .dataSource(dataSource)
    .build();
}
```

- Job listener
   - The `JobCompletionNotificationListener` listens for when a job is BatchStatus.COMPLETED and then uses JdbcTemplate to inspect the results.

```java
@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! Time to verify the results");

      jdbcTemplate.query("SELECT first_name, last_name FROM people",
        (rs, row) -> new Person(
          rs.getString(1),
          rs.getString(2))
      ).forEach(person -> log.info("Found <" + person + "> in the database."));
    }
  }
}
```

## ref
- https://spring.io/guides/gs/batch-processing/