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BATCH-599:Added additional content to the section on TaskletStep

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lucasward
2008-04-22 02:43:05 +00:00
parent 75434bd244
commit 447997a5bc
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docs/src/site/docbook/reference/execution.xml
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@@ -1304,6 +1304,94 @@
<property name="tasklet" ref="tasklet" />
<property name="jobRepository" ref="repository" />
&lt;/bean&gt;</programlisting>
<section>
<title>TaskletAdapter</title>
<para>As with other adapters for the <classname>ItemWriter</classname>
and <classname>ItemReader</classname> interfaces, the
<classname>Tasklet</classname> interface contains an implementation
that allows for adapting itself to any pre-existing class:
<classname>TaskletAdapter</classname>. An example where this may be
useful is an existing DAO that is used to upate a flag on a set of
records. The <classname>TaskletAdapter</classname> can be used to call
this class without having to write an adapter for the
<classname>Tasklet</classname> interface:</para>
<programlisting> &lt;bean id="deleteFilesInDir" parent="taskletStep"&gt;
&lt;property name="tasklet"&gt;
&lt;bean class="org.springframework.batch.core.step.tasklet.TaskletAdapter"&gt;
&lt;property name="targetObject"&gt;
&lt;bean class="org.mycompany.FooDao"&gt;
&lt;/property&gt;
&lt;property name="targetMethod" value-"updateFoo" /&gt;
&lt;/bean&gt;
&lt;/property&gt;
&lt;/bean&gt;</programlisting>
</section>
<section>
<title>Example Tasklet implementation</title>
<para>Many batch jobs contains steps that must be done before the main
processing begins in order to set up various resources, or after
processing has completed to cleanup those resources. In the case of a
job that works heavily with files, it is often necessary to delete
certain files locally after they have been uploaded successfully to
another location. The example below taken from the Spring Batch
samples project, is a <classname>Tasklet</classname> implementation
with just such a responsibility:</para>
<programlisting> public class FileDeletingTasklet implements Tasklet, InitializingBean {
private Resource directory;
public ExitStatus execute() throws Exception {
File dir = directory.getFile();
Assert.state(dir.isDirectory());
File[] files = dir.listFiles();
for (int i = 0; i &lt; files.length; i++) {
boolean deleted = files[i].delete();
if (!deleted) {
throw new UnexpectedJobExecutionException("Could not delete file " + files[i].getPath());
}
}
return ExitStatus.FINISHED;
}
public void setDirectoryResource(Resource directory) {
this.directory = directory;
}
public void afterPropertiesSet() throws Exception {
Assert.notNull(directory, "directory must be set");
}
}</programlisting>
<para>The above <classname>Tasklet</classname> implementation will
delete all files within a given directory. It should be noted that the
<methodname>execute</methodname> method will only be called once. All
that is left is to inject the <classname>Tasklet</classname> into a
<classname>TaskletStep</classname>:</para>
<programlisting> &lt;bean id="taskletJob" parent="simpleJob"&gt;
&lt;property name="steps"&gt;
&lt;bean id="deleteFilesInDir" parent="taskletStep"&gt;
&lt;property name="tasklet"&gt;
&lt;bean class="org.springframework.batch.sample.tasklet.FileDeletingTasklet"&gt;
&lt;property name="directoryResource" ref="directory" /&gt;
&lt;/bean&gt;
&lt;/property&gt;
&lt;/bean&gt;
&lt;/property&gt;
&lt;/bean&gt;
&lt;bean id="directory"
class="org.springframework.core.io.FileSystemResource"&gt;
&lt;constructor-arg value="target/test-outputs/test-dir" /&gt;
&lt;/bean&gt;</programlisting>
</section>
</section>
</section>