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Subject [Apache Struts Wiki] New: StrutsFileUpload
Date Mon, 04 Oct 2004 23:14:21 GMT
   Date: 2004-10-04T16:14:21
   Editor: NiallPemberton <>
   Wiki: Apache Struts Wiki
   Page: StrutsFileUpload

   no comment

New Page:

= File Upload - Simple Example =

== HTML ==

This isn't specific to Struts, but gives a simple example of the HTML required to upload a
single file.

Two things are needed in the html page. Firstly, the form needs to specify an ''enctype''
of ''multipart/form-data'' and secondly an <input> form control of type ''file''.

   <form name="myForm" method="post" action="/mywebapp/" enctype="multipart/form-data">

         Select File: <input type="file" name="myFile"> </br>

         <input type="submit" value="Upload File">


== JSP ==

The above HTML can be generated using the Struts tags in the following way

   <html:form action="/" enctype="multipart/form-data">

         Select File: <html:file property="myFile"> </br>

         <html:submit value="Upload File"/>


== ActionForm ==

The ActionForm needs a property of type FormFile.

=== Regular ActionForms ===

    import org.apache.struts.upload.FormFile;

    public class MyActionForm extends ActionForm {

       private FormFile myFile;

       public void setMyFile(FormFile myFile) {
           this.myFile = myfile;

       public FormFile getMyFile() {
           return myFile;

=== Dyna ActionForms ===

In the struts-config.xml

   <form-bean name="myForm" type="org.apache.struts.action.DynaActionForm">
       <form-property name="myFile" type="org.apache.struts.upload.FormFile"/>

== Whats Needed in the Action ==

Nothing special really, just retrieve the FormFile from the ActionForm, as you would any other
property, and process it as you like. You can get the file name, size and file contents from
the FormFile.

    public ActionForward execute(ActionMapping mapping,
                                 ActionForm form,
                                 HttpServletRequest request,
                                 HttpServletResponse response) throws Exception {

        MyActionForm myForm = (MyActionForm)form;

        // Process the FormFile
        FormFile myFile = myForm.getMyFile();
        String contentType = myFile.getContentType();
        String fileName    = myFile.getFileName();
        int fileSize       = myFile.getFileSize();
        byte[] fileData    = myFile.getFileData();

= File Upload Configuration =

The following parameters can be set in the <controller> element of the struts-config.xml
to configure file upload:

 * '''bufferSize''' - The size (in bytes) of the input buffer used when processing file uploads.
Default is 4096.
 * '''maxFileSize''' - The maximum size (in bytes) of a file to be accepted as a file upload.
Can be expressed as a number followed by a "K", "M", or "G", which are interpreted to mean
kilobytes, megabytes, or gigabytes, respectively. Default is 250M.
 * '''multipartClass''' - The fully qualified Java class name of the multipart request handler
class to be used with this module. Defaults is org.apache.struts.upload.CommonsMultipartRequestHandler.

 * '''tempDir''' - Temporary working directory to use when processing file uploads.

Above taken from the Configuration section in the [
User Guide].

= Plugging in an Alternative File Upload Mechanism =

By default Struts uses Commons [ File Upload].

Alternative implementations can be  plugged as long as they implement the '''org.apache.struts.upload.MultipartRequestHandler'''
interface and Struts configured to use that implementation by specifying it in the '''multipartClass'''
parameter in the <controller> element of the struts-config.xml

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