Let me rephrase your question a bit and see if this addresses it.
What does Spring Batch provide that I'd have to handle myself when building a batch application?
Spring Batch served as the basis for JSR-352 (the java batch specification) and since that specification has come out, there is a lot of Spring Batch now available within the java space. That being said, there is still a lot that Spring Batch provides outside of the scope of what basic Java does:
Within a "basic" batch job
Within the scope of a simple batch job, Spring Batch provides a collection of utilities and implementations that have been battle tested in all enterprise verticals. Some examples are:
- Over 17
ItemReader and 15 ItemWriter implementations covering vast options for input and output (File, JDBC, NoSQL, JMS, etc). All of these provide declarative I/O options so that you don't have to write and test code for stateful readers and writers.
- A collection of
Tasklet (Spring Batch's equivalent to JSR-352's Batchlet) implementations including ones for executing shell commands and interfacing with Hadoop.
- The ability to stop/start/restart jobs and maintain state between executions.
- The ability to skip and retry records as they are being processed.
- Transaction management. Spring Batch handles transactions for you.
- The ability to notify other systems when errors occur via messaging by integrating Spring Integration.
- Java or XML based configuration.
- All the Spring features like DI, AOP, testability, etc.
- Vendor independence - By using Spring Batch, you get to use a framework that open source and not tied to any one vendor.
Additional advantages
Beyond the above examples of what Spring Batch brings to the table, it goes much further:
- Scalability options - Spring Batch provides a number of scalability options that range from within a single JVM via threads (multithreaded step, local partitioning, and splits) to multi-JVM scalability (remote partitioning and remote chunking).
- Integration with Spring Integration - Spring Integration provides a number of useful elements that allow you to build robust batch applications to handle things like error messages, poling directories for files, automatically FTPing files, etc.
- Big data support - Through the Spring for Apache Hadoop project, there are a number of extensions to Spring Batch that allow it to work well with Hadoop. You can run Spring Batch jobs on YARN, you can execute Pig, Hive, MapReduce, etc jobs.
- Integration with Spring XD - Spring XD provides a distributed runtime for the deployment, management, and execution of batch jobs.
I personally view batch processing as the "set it and forget it" model of programming. While it isn't sexy, batch processing is a very useful model of processing and is more useful in places than most people realize. Spring Batch provides an environment that makes developing robust batch jobs as easily as possible.
