README.md

Spring Batch POC

The Spring Batch project contains five basic components:

• Reader : where's the data is being read, such as database, file or even a queue.
• Processor : is the actual data transformation.
• Writer : where's the data is being written, could be also a database, file or a queue.
• Job : the actual job to be executed.
• Step : the job step OR steps.

We must configure the reader, processor, writer, job and step as beans on a BatchConfig class.

Note that each Job can contain multiple steps, and a step can contain a reader, processor and a writer.

READER

Spring Batch module give us multiple ways to configure our components. In this POC project we defined the FlatFileItemReader:

@Bean
public FlatFileItemReader<Person> reader() {
    return new FlatFileItemReaderBuilder<Person>()
            .name("personItemReader")
            .resource(new ClassPathResource("sample-data.csv"))
            .delimited()
            .names("firstName", "lastName")
            .targetType(Person.class)
            .build();
}

• Our FlatFile is the sample-data.csv on resources folder
• We must tell where the file is being loaded from, the delimiter type (in this case spring can automatically tell it's comma between the Person fields.)
• The field names from our Object
• The actual Object, targetType.

PROCESSOR

The PersonItemProcessor implements the ItemProcessor interface from Spring Batch project where receives an Input and returns an Output:

In this sample project Input and Output are the Person java record.

Note that if the output returns null, the processing will stop.

public interface ItemProcessor<I, O>

Batch applications can be categorized by the input source:

• Database-driven applications
• File-driven applications
• Message-driven applications