Java Reference
In-Depth Information
<batch-artifacts xmlns=" ">
<ref id="acmeReader" class="org.javaee7.chapter11.AcmeReader"/>
<ref id="acmeProcessor" class="org.javaee7.chapter11.AcmeProcessor"/>
<ref id="acmeWriter" class="org.javaee7.chapter11.AcmeWriter"/>
The implementation classes should either extend abstract classes (reader and writer), or implement an interface
(processor). The ItemReader implementation class ( AcmeReader in the example) extends the AbstractItemReader
, and accepts an object into which the read items will be stored. In the example, that object class is named
WidgetReportItem . As such, the class should implement the readItem method, which is responsible for performing
the reading. The method should return the object to which the items are read, or return a null when there are no
more items to read.
public class AcmeReader extends AbstractItemReader<WidgetReportItem> {
public WidgetReportItem readItem() throws Exception {
Path file = Paths.get("widgetFile.txt");
List<String> fileLines;
Charset charset = Charset.forName("US-ASCII");
fileLines = Files.readAllLines(file, charset);
for(String line:fileLines){
return new WidgetReportItem(line);
return null;
The ItemProcessor class implementation ( AcmeProcessor in the example) is responsible for performing
processing for the chunk, and it should implement the ItemProcessor interface, accepting both the object containing
the read items, and an object to which the processed items will be stored. The ItemProcessor implementation class
should implement a processItem method, which is responsible for performing the processing.
The ItemWriter class implementation ( AcmeWriter in the example) is responsible for performing the writing
for the chunk. The class implementation should extend the AbstractItemWriter class, and accept the object to which
the processed items will be written. This implementation must contain the writeItems method, which is responsible
for performing the writing.
Example of Item-Oriented Processing
In this example, a batch process is created to read text from a file, process that text accordingly, and then write
out the processed text. To begin, construct an XML file to define the job. The XML file for this example will be
called acmeFileProcessor.xml . Let's take a look at what a job process looks like. The lines below are from the
acmeFileProcessor.xml file.
<?xml version="1.0" encoding="UTF-8"?>
<job id="acmeFileProcessor" xmlns=" http://batch.jsr352/jsl " >
<step id="readingStep" >
<chunk item-count="2">
<reader ref="acmeReader"></reader>
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