Jetty, "No multipart config for servlet" problem

Question

I'm writing handler for file transfer. The request is multipart HTTP message. The message is correct - tested on other servers.

The problem is "java.lang.IllegalStateException: No multipart config for servlet" on getParts() call.

The test code:

@SuppressWarnings("serial")
@MultipartConfig
@WebServlet(urlPatterns={"/upload"}, name="upload")
public class FilesServlet extends HttpServlet
{
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        resp.setContentType("text/plain");
        PrintWriter out = resp.getWriter();

        int i=0;
        for(Part part: req.getParts())
        {
            out.printf("Got part: name=%s, size=%d%n",part.getName(), part.getSize());
            part.write(String.format("part-%02d.dat",i++));
        }
    }
}

The exception:

java.lang.IllegalStateException: No multipart config for servlet
    at org.eclipse.jetty.server.Request.getParts(Request.java:2327)
    at org.eclipse.jetty.server.Request.getParts(Request.java:2314)
    at com.rad.server.servlet.FilesServlet.doPost(FilesServlet.java:31)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:860)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:535)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
    at org.eclipse.jetty.server.Server.handle(Server.java:530)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:347)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:256)
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279)
    at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:102)
    at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:247)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.produce(EatWhatYouKill.java:140)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:708)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:626)
    at java.lang.Thread.run(Thread.java:745)

The jars are: jetty-server-9.4.8 and javax-servlet-api-3.10.

What is wrong here?

Answer 1

Actually, I didn't found why @MultipartConfig annotation doesn't work for me, but I found on i-net kind of workaround that works fine:

     private static final MultipartConfigElement MULTI_PART_CONFIG = new MultipartConfigElement("c:/temp");
        ...
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String contentType = request.getContentType();

        if(contentType != null && contentType.startsWith("multipart/")){
           request.setAttribute(Request.__MULTIPART_CONFIG_ELEMENT, MULTI_PART_CONFIG);
           for(Part part: request.getParts()) { ... } ;
        } else {  
            ...
        }          
      }

I think that this solution may be useful for developers who faced such problem

Answer 2

why not configure that when you map your servlet to the path?

handler.addServlet(UploadServlet.class, "/upload/*")
  .getRegistration().setMultipartConfig(
    new MultipartConfigElement("./tmp")
  );

each request came to this servlet will be enriched with that property