concept FlatFileItemReader in category spring

This is an excerpt from Manning's book Spring Batch in Action. Login to get full access to this book.

Spring Batch provides the FlatFileItemReader class to read records from a flat file. To use a FlatFileItemReader, you need to configure some Spring beans and implement a component that creates domain objects from what the FlatFileItemReader reads; Spring Batch will handle the rest. You can kiss all your old boilerplate I/O code goodbye and focus on your data.

Creating Domain Objects with a FlatFileItemReader

The FlatFileItemReader class handles all the I/O for you: opening the file, streaming it by reading each line, and closing it. The FlatFileItemReader class delegates the mapping between an input line and a domain object to an implementation of the LineMapper interface. Spring Batch provides a handy LineMapper implementation called DefaultLineMapper, which delegates the mapping to other strategy interfaces. Figure 1.9 shows all of this delegation work.

Figure 1.9. The FlatFileItemReader reads the flat file and delegates the mapping between a line and a domain object to a LineMapper. The LineMapper implementation delegates the splitting of lines and the mapping between split lines and domain objects.

Listing 5.1. Configuring a FlatFileItemReader

<bean id="productItemReader" class="org.springframework.batch.item.file.FlatFileItemReader"> <property name="resource" value="datafile.txt"/> <property name="linesToSkip" value="1"/> <property name="recordSeparatorPolicy" ref="productRecordSeparatorPolicy"/> <property name="lineMapper" ref="productLineMapper"/> </bean> <bean id="productRecordSeparatorPolicy" class="(...)"> (...) </bean> <bean id="productLineMapper" class="(...)"> (...) </bean>