Java Configuration with Spring Batch

In the first post in this series, I introduced Spring's Java configuration mechanism. There is the base configuration style, and - as we saw - there are annotations (like @EnableWebMvc) that turn on container-wide, and often conventions-oriented features. In the case of @EnableWebMvc, the annotation enables Spring MVC and turns on support for correctly exposing @Controller-annotated beans as HTTP endpoints. Java configuration APIs of the same style as @EnableWebMvc can often optionally implement interfaces that are used to contribute, change, or otherwise tailor the API. Most Spring projects today offer beta-or-better APIs that work in this same manner. In this post, we'll look at Spring Batch's Java Configuration API available in the upcoming 2.2 release.

Spring Batch provides a solution for batch processing. It lets you describe jobs, which themselves have steps, which read input from some source system (a large RDBMS dataset, a large CSV file or XML document, etc.), optionally process the input, and then write the output to a destination system like an RDBMS, a file, or a message queue.

@Configuration
@EnableBatchProcessing
public class BatchInfrastructureConfiguration   {
@Bean
public TaskScheduler taskScheduler() {
    return new ConcurrentTaskScheduler();
}

@Bean
public PlatformTransactionManager transactionManager(DataSource ds) {
    return new DataSourceTransactionManager(ds);
}


@Bean
public DataSource dataSource(Environment environment) {

    String pw = environment.getProperty("dataSource.password"),
            user = environment.getProperty("dataSource.user"),
            url = environment.getProperty("dataSource.url");

    Class<Driver> classOfDs = environment.getPropertyAsClass("dataSource.driverClassName", Driver.class);

    SimpleDriverDataSource dataSource = new SimpleDriverDataSource();
    dataSource.setPassword(pw);
    dataSource.setUrl(url);
    dataSource.setUsername(user);
    dataSource.setDriverClass(classOfDs);

    return dataSource;
}

}

Once you've done this, you can start describing jobs using the Spring Batch configuration DSL. Here, we define a job named flickrImportJob which in turn has one step, step1, that in turn reads data using an ItemReader named photoAlbumItemReader and writes data using an ItemWriter named photoAlbumItemWriter.

@Configuration
@Scope(proxyMode = ScopedProxyMode.TARGET_CLASS)
@Import(BatchInfrastructureConfiguration.class)
public class BatchImporterConfiguration {
@Bean(name = "flickrImportJob")
public Job flickrImportJob(
        JobBuilderFactory jobs,
        @Qualifier("step1") Step s1 
) {
    return jobs.get("flickrImportJob")
            .flow(s1)            
            .end()
            .build();
}


@Bean(name = "step1")
public Step step1(StepBuilderFactory stepBuilderFactory,
                  @Qualifier("photoAlbumItemReader") ItemReader<PhotoSet> ir,
                  @Qualifier("photoAlbumItemWriter") ItemWriter<PhotoSet> iw
) {
    return stepBuilderFactory.get("step1")
            .<PhotoSet, PhotoSet>chunk(10)
            .reader(ir)
            .writer(iw)
            .build();
}
// ... omitting definitions of ItemReader and ItemWriters 

}