SWF-1113 - File Upload - Add a section to the documentation showing how to do file upload

spring-webflow-reference/src/actions.xml

@@ -399,6 +399,59 @@ public class PrintBoardingPassAction extends AbstractAction {
 				In this example, when the print event is raised the flow will call the printBoardingPassAction.
 				The action will render the PDF then mark the response as complete.
 			</para>
+		</sect2>
+		<sect2 id="file-upload">
+			<title>Handling File Uploads</title>
+			<para>
+				Another common task is to use Web Flow to handle multipart file uploads in combination with Spring MVC's 
+				<code>MultipartResolver</code>.  Once the resolver is set up correctly <ulink url="">as described here</ulink> and the submitting
+				HTML form is configured with <code>enctype="multipart/form-data"</code>, you can easily handle the file upload in a 
+				transition action.  Given a form such as:     
+			</para>
+			<programlisting language="xml"><![CDATA[
+<form:form modelAttribute="fileUploadHandler" enctype="multipart/form-data">
+	Select file: <input type="file" name="file"/>		
+	<input type="submit" name="_eventId_upload" value="Upload" />			
+</form:form>]]>
+			</programlisting>
+			<para>
+				and a backing object for handling the upload such as:
+			</para>
+			<programlisting language="java"><![CDATA[
+package org.springframework.webflow.samples.booking;
+
+import org.springframework.web.multipart.MultipartFile;
+
+public class FileUploadHandler {
+    
+    private transient MultipartFile file;
+    
+    public void processFile() {
+		//Do something with the MultipartFile here
+    }
+
+    public void setFile(MultipartFile file) {
+        this.file = file;
+    } 
+}]]>
+			</programlisting>
+			<para>
+				you can process the upload using a transition action as in the following example:
+			</para>
+			<programlisting language="xml"><![CDATA[
+<view-state id="uploadFile" model="uploadFileHandler">
+    <var name="fileUploadHandler" class="org.springframework.webflow.samples.booking.FileUploadHandler" />
+    <transition on="upload" to="finish" >
+        <evaluate expression="fileUploadHandler.processFile()"/>
+    </transition>
+    <transition on="cancel" to="finish" bind="false"/>
+</view-state>]]>
+			</programlisting>
+			<para>
+				The <code>MultipartFile</code> will be bound to the <code>FileUploadHandler</code> bean as 
+				part of the normal form binding process so that it will be available to process during the 
+				execution of the transition action.
+			</para>
 		</sect2>			
 	</sect1>
 </chapter>