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BATCH-691:Updated MultiResourceItemReader section

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lucasward
2008-07-08 02:25:04 +00:00
parent 24b16016ae
commit bbf2e2dc7a
1 changed files with 19 additions and 21 deletions
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40
docs/src/site/docbook/reference/readersAndWriters.xml
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@@ -1182,28 +1182,18 @@
<section>
<title>Multi-File Input</title>
<para>It a is common requirement to process multiple files in a single
step (e.g. all files in given directory, or files matching given pattern).
<classname>MultiResourceItemReader</classname> supports multi-file input
by wrapping a delegate
<classname>ResourceAwareItemReaderItemStream</classname> (both
<classname>FlatFileItemReader</classname> and
<classname>StaxEventItemReader</classname> implement this interface).
<classname>MultiResourceItemReader</classname> uses the delegate to read
items from the resource and takes care of correct rollback functionality
(potentially spanning file boundaries) as well as efficient restart (skips
already processed files without re-reading them).</para>
<para>It is a common requirement to process multiple files within a single
Step. Assuming the files are all formatted the same, the
<classname>MultiResourceItemReader</classname> supports this type of input
for both XML and FlatFile processing. Consider the following files in a
directory:</para>
<para>To restart correctly file ordering needs to be preserved between job
runs, which may not be easy to guarantee. In such circumstances we suggest
to use <classname>SortedMultiResourceItemReader</classname> which first
sorts resources using injected <classname>Comparator</classname>. By
default resources are ordered alphabetically by filename.</para>
<programlisting>file-1.txt file-2.txt ignored.txt</programlisting>
<para>Below is an example configuration where the
<classname>SortedMultiResourceItemReader</classname> is configured to read
multiple flat files (note standard Spring syntax is used to specify the
resources):</para>
<para>file-1.txt and file-2.txt are formatted the same and for business
reasons should be processed together. The
<classname>MuliResourceItemReader</classname> can be used to read in both
files by using wildcards:</para>
<programlisting>
&lt;bean id="multiResourceReader" class="org.springframework.batch.item.SortedMultiResourceItemReader"&gt;
@@ -1212,6 +1202,14 @@
&lt;/bean&gt;
</programlisting>
<para>The referenced delegate is a simple
<classname>FlatFileItemReader</classname>. The above configuration will
read input from both files, handling rollback and restart scenarios. It
should be noted that, as with any ItemReader, adding extra input (in this
case a file) could cause potential issues when restarting. It is
recommended that batch jobs work with their own individual directories
until completed successfully. </para>
</section>
<section>
@@ -2225,7 +2223,7 @@
&lt;property name="mapper"&gt;
&lt;bean class="org.springframework.batch.sample.mapping.PlayerSummaryMapper" /&gt;
&lt;/property&gt;
&lt;property name="saveState" value="false" /&gt;
<emphasis role="bold">&lt;property name="saveState" value="false" /&gt;</emphasis>
&lt;property name="sql"&gt;
&lt;value&gt;
SELECT games.player_id, games.year_no, SUM(COMPLETES),