How to bypass struts2 interceptors on file upload

Question

I wrote a simple page with a form to upload a file and a jsp to handle that file.

My problem is that when the file is uploaded, the request object is handled by Struts interceptors and when it comes to the jsp page it is already "consumed", so the calls to read the request with methods such as "ServletFileUpload.parseRequest()" returns empty lists.

I have already found a working solution, but this needs to restart Tomcat, and since the page has to be added on the production server, it would be so much better if there is a way to not restart it.

For now, what I tried and worked is this:
1) in struts.xml i added

<include file="custom/struts-custom.xml"/>

2) in the struts-custom.xml i wrote:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd">
    <struts>
        <constant name="struts.action.excludePattern" value="/path_to_my_jsp/page.jsp"/>
    </struts>

With this i can upload the file bypassing struts interceptors.

Is there a better / cleaner solution? as i said, the best would be a solution that doesn't need to restart the application server.

Even if i don't think that the problem is related to code, i will post it.

page.html:

<form action="upload.jsp" method="post" enctype="multipart/form-data" TARGET="Report_Down"
onSubmit="if(document.getElementById('file1').value == '') return false;">
    Input File <input type="file" name="file1" id="file1">
    <input type="submit" value="Upload">
</form>

upload.jsp:

boolean isMultipart = ServletFileUpload.isMultipartContent(request);

if (!isMultipart) {
    return;
}

DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setSizeThreshold(1024 * 1024 * 2);
factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
String uploadFolder = getServletContext().getRealPath("")
        + File.separator + DATA_DIRECTORY;

ServletFileUpload upload = new ServletFileUpload(factory);
upload.setSizeMax(1024 * 1024);

try {
    List items = upload.parseRequest(request);

    Iterator iter = items.iterator();
    while (iter.hasNext()) {
        FileItem item = (FileItem) iter.next();

        if (!item.isFormField()) {
            try {
                String fileName = new File(item.getName()).getName();
                String filePath = uploadFolder + File.separator + fileName;
                File uploadedFile = new File(filePath);
                item.write(uploadedFile);

                //do something...
            }
            catch(Exception e) {
                //...
            }
        }
    }

getServletContext().getRequestDispatcher(forwardUrl).forward(
            request, response);

} catch (FileUploadException ex) {
    throw new ServletException(ex);
} catch (Exception ex) {
    throw new ServletException(ex);
}

Thank you in advance :)

Answer 1

What do you mean with the request is consumed ? The request passes through the Interceptor Stack up to the Action, and is still there.
If, for some reason (and you should not have one, when doing a simple upload of a file), you need to run code out of the framework mechanisms (Actions, Interceptors etc), you can use a Servlet.

By the way, this is the correct way of uploading a file in Struts2, and your problem is mostly related to

1. the maximum file/request cap hit;
2. a wrong definition of the interceptor stack.

I bet on n.1, but if this still haven't solved your problem, post more details about your struts.xml.

Also remember to avoid using scriptlets (as already suggested by Boris) and to never call JSPs directly: always pass through an Action.