Simple Jetty/JSF file upload won't submit - jsf

Question

I've already looked at this one and the related tickets to no avail.
I have, what looks like the, simplest example possible
<h:form enctype="multipart/form-data" prependId="false">
<h:outputText value="File: "></h:outputText>
<h:inputFile value="#{configUploadController.uploadedFile}" />
<h:commandButton value="Save" type="submit" action="#{configUploadController.uploadFile}" style="color: red;"></h:commandButton>
</h:form>
I put a breakpoint in my uploadFile method but it never gits hit. when I remove the enctype from the form it does try to submit but then I get the obvious error...
javax.servlet.ServletException: Content-Type != multipart/form-data
And just for completeness, I remove the <h:inputFile> and enctype and can see my breakpoint being hit. When I set enctype to text/plain it DOESNT hit the breakpoint. However, when I set enctype to gibberish it DOES hit the breakpoint :(
Am I missing a dependency or config somewhere?
And in case it matters, my web.xml...
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<!-- File(s) appended to a request for a URL that is not mapped to a web
component -->
<welcome-file-list>
<welcome-file>status.xhtml</welcome-file>
</welcome-file-list>
<context-param>
<param-name>com.sun.faces.expressionFactory</param-name>
<param-value>com.sun.el.ExpressionFactoryImpl</param-value>
</context-param>
<listener>
<description>Initializes Oracle JSF</description>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
<!-- Define the JSF servlet (manages the request processing life cycle for
JavaServer Faces) -->
<servlet>
<servlet-name>faces-servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>0</load-on-startup>
</servlet>
<!-- Map following files to the JSF servlet -->
<servlet-mapping>
<servlet-name>faces-servlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
</web-app>
jsf-api-2.2.15
jsf-impl-2.2.15
el-api-2.2
el-impl-2.2
jetty 9.4.18
javax.servlet-api-3.1.0

Answer 1

Instead of working around with a servlet (as per other answer) the actual problem was Jetty needs the multipart config setting up per multipart request.
Simple way to do this would be to add a filter that adds it as necessary, eg.
public class LoginFilter implements Filter {
private static final String MULTIPART_FORM_DATA = "multipart/form-data";
private static final MultipartConfigElement MULTI_PART_CONFIG =
new MultipartConfigElement(System.getProperty("java.io.tmpdir"));
#Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest httpServletRequest = (HttpServletRequest) request;
HttpServletResponse httpServletResponse = (HttpServletResponse) response;
String contentType = request.getContentType();
if (contentType != null && contentType.startsWith(MULTIPART_FORM_DATA))
request.setAttribute(Request.__MULTIPART_CONFIG_ELEMENT, MULTI_PART_CONFIG);
filterChain.doFilter(request, response);
}
}
See also:
How to implement FileUpload in embedded Jetty?

Answer 2

So, I haven't spent the time to track down why but jetty doesn't appear to like multipart forms. I got round it by using a servlet. Solution looks like this...
I've gone with ajax approach and a HTML form so I can specify my action, that matches the servlets pattern...
<form action="upload/config" enctype="multipart/form-data" method="post">
<h:inputFile id="file" />
<br />
<h:commandButton type="submit" value="Upload">
<f:ajax execute="file" render="#all"/>
</h:commandButton>
</form>
And the servlet...
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import javax.servlet.MultipartConfigElement;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import org.eclipse.jetty.server.Request;
#WebServlet("upload")
#MultipartConfig
public class UploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
#Override
protected void doPost(HttpServletRequest request, HttpServletResponse resp) {
try {
// This needed to get access to the parts
MultipartConfigElement multipartConfigElement = new MultipartConfigElement((String)null);
request.setAttribute(Request.__MULTIPART_CONFIG_ELEMENT, multipartConfigElement);
Part filePart = request.getPart("file");
try ( InputStream inputStream = filePart.getInputStream(); ) {
// Do what you want with your part
} catch (Exception e) {
resp.setStatus(500);
}
} catch (Exception e) {
resp.setStatus(500);
}
}
}