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INT-2769 Document Filename Generation Options

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INT-2769 - Document filename-generator + filename-generator-expression

For reference see: https://jira.springsource.org/browse/INT-2769

INT-2769 Polishing
This commit is contained in:
Gunnar Hillert
2013-02-07 16:58:57 -05:00
committed by Gary Russell
parent 0602f88c9f
commit 208d022ca6
1 changed files with 67 additions and 8 deletions
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75
src/reference/docbook/file.xml
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@@ -157,16 +157,10 @@
<classname><ulink url="http://static.springsource.org/spring-integration/api/org/springframework/integration/file/FileWritingMessageHandler.html">FileWritingMessageHandler</ulink></classname>.
This class can deal with <emphasis>File</emphasis>,
<emphasis>String</emphasis>, or <emphasis>byte array</emphasis>
payloads. In its simplest form the <classname>FileWritingMessageHandler</classname>
only requires a destination directory for writing the files. The name
of the file to be written is determined by the handler's
<classname><ulink url="http://static.springsource.org/spring-integration/api/org/springframework/integration/file/FileNameGenerator.html">FileNameGenerator</ulink></classname>.
The <ulink url="http://static.springsource.org/spring-integration/api/org/springframework/integration/file/DefaultFileNameGenerator.html">default implementation</ulink>
looks for a Message header whose key matches the constant defined as
<code>FileHeaders.FILENAME</code>.
payloads.
</para>
<para>
Additionally, you can configure the encoding and the charset that
You can configure the encoding and the charset that
will be used in case of a String payload.
</para>
<para>
@@ -175,6 +169,71 @@
<emphasis>Outbound Gateway</emphasis> using the provided XML namespace
support.
</para>
<section id="file-writing-file-names">
<title>Generating Filenames</title>
<para>
In its simplest form, the <classname>FileWritingMessageHandler</classname>
only requires a destination directory for writing the files. The
name of the file to be written is determined by the handler's
<classname><ulink url="http://static.springsource.org/spring-integration/api/org/springframework/integration/file/FileNameGenerator.html">FileNameGenerator</ulink></classname>.
The <ulink url="http://static.springsource.org/spring-integration/api/org/springframework/integration/file/DefaultFileNameGenerator.html">default implementation</ulink>
looks for a Message header whose key matches the constant defined
as <code><ulink url="http://static.springsource.org/spring-integration/api/constant-values.html#org.springframework.integration.file.FileHeaders.FILENAME">FileHeaders.FILENAME</ulink></code>.
</para>
<para>
Alternatively, you can specify an expression
to be evaluated against the Message in order to generate a file name, e.g.:
<emphasis>headers['myCustomHeader'] + '.foo'</emphasis>. The expression must
evaluate to a <classname>String</classname>. For convenience,
the <classname>DefaultFileNameGenerator</classname> also
provides the <emphasis>setHeaderName</emphasis> method, allowing you
to explicitly specify the Message header whose value shall be
used as the filename.
</para>
<para>
Once setup, the <classname>DefaultFileNameGenerator</classname> will
employ the following resolution steps to determine the filename
for a given Message payload:
</para>
<orderedlist>
<listitem>
Evaluate the expression against the Message and, if the result is a
non-empty <classname>String</classname>, use it as the
filename.
</listitem>
<listitem>
Otherwise, if the payload is a <classname>java.io.File</classname>, use the
file's filename.
</listitem>
<listitem>
Otherwise, use the Message ID appended with <quote>.msg</quote>
as the filename.
</listitem>
</orderedlist>
<para>
When using the XML namespace support, both, the
<emphasis>File Oubound Channel Adapter</emphasis> and
the <emphasis>File Outbound Gateway</emphasis> support the
following two mutually exclusive configuration attributes:
</para>
<itemizedlist>
<listitem><code>filename-generator</code> (a reference to a <classname>FileNameGenerator</classname>) implementation)</listitem>
<listitem><code>filename-generator-expression</code> (an expression evaluating to a <classname>String</classname>)</listitem>
</itemizedlist>
<para>
While writing files, a temporary file suffix will be used (default:
<quote>.writing</quote>). It is appended to the filename while
the file is being written. To customize the suffix, you
can set the <emphasis>temporary-file-suffix</emphasis> attribute
on both, the <emphasis>File Oubound Channel Adapter</emphasis> and
the <emphasis>File Outbound Gateway</emphasis>.
</para>
<note>
When using the <emphasis>APPEND</emphasis> file <emphasis>mode</emphasis>,
the <emphasis>temporary-file-suffix</emphasis> attribute is ignored,
since the data is appended to the file directly.
</note>
</section>
<section id="file-writing-output-directory">
<title>Specifying the Output Directory</title>
<para>