Java Reference
In-Depth Information
9-5. Writing a Custom ItemWriter and ItemReader
You want to talk to a resource (you might imagine an RSS feed, or any other custom data format) that
Spring Batch doesn't know how to connect to.
You can easily write your own ItemWriter or ItemReader . The interfaces are drop dead simple and there's
not a lot of responsibility placed on the implementations.
How It Works
As easy and trivial as this process is to do, it's still not better than just reusing any of the numerous
provided options. If you look, you'll likely find something. There's support for writing JMS
( JmsItemWriter ), JPA ( JpaItemWriter ), JDBC ( JdbcBatchItemWriter ), Files ( FlatFileItemWriter ),
iBatis ( IbatisBatchItemWriter ), and more. There's even support for “writing” by invoking a method
on a bean ( PropertyExtractingDelegatingItemWriter ) and passing to it as arguments the properties on
the Item to be written! There's a slightly smaller but impressive set of implementations for ItemReader
Writing a Custom ItemReader
The ItemReader example is trivial. Here an ItemReader is created that knows how to retrieve
UserRegistration objects from an (remote procedure call (RPC) endpoint:
package com.apress.springenterpriserecipes.springbatch.solution2;
import java.util.Collection;
import java.util.Date;
import org.springframework.batch.item.ItemReader;
import org.springframework.batch.item.ParseException;
import org.springframework.batch.item.UnexpectedInputException;
import org.springframework.beans.factory.annotation.Autowired;
import com.apress.springenterpriserecipes.springbatch.
import com.apress.springenterpriserecipes.springbatch.solution1.
public class UserRegistrationItemReader implements ItemReader<UserRegistration> {
private UserRegistrationService userRegistrationService;
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