Handling Multi-Part Form Posts

The Juneau framework does not natively support multipart form posts. However, it can be done in conjunction with the Apache Commons File Upload library or through the Servlet 3.0 API directly.

The following is an example that uses the File Upload library to allow files to be uploaded as multipart form posts.

##### Example:

@Rest( path="/tempDir" ) public class TempDirResource extends DirectoryResource { /** * [POST /upload] - Upload a file as a multipart form post. * Shows how to use the Apache Commons ServletFileUpload class for handling multi-part form posts. */ @RestMethod(name=POST, path="/upload", matchers=TempDirResource.MultipartFormDataMatcher.class) public Redirect uploadFile(RestRequest req) throws Exception { ServletFileUpload upload = new ServletFileUpload(); FileItemIterator iter = upload.getItemIterator(req); while (iter.hasNext()) { FileItemStream item = iter.next(); if (item.getFieldName().equals("contents")) { File f = new File(getRootDir(), item.getName()); IOPipe.create(item.openStream(), new FileOutputStream(f)).closeOut().run(); } } return new Redirect(); // Redirect to the servlet root. } /** Causes a 404 if POST isn't multipart/form-data */ public static class MultipartFormDataMatcher extends RestMatcher { @Override /* RestMatcher */ public boolean matches(RestRequest req) { String contentType = req.getContentType(); return contentType != null && contentType.startsWith("multipart/form-data"); } }

The following shows using the HttpServletRequest.getParts() method to retrieve multi-part form posts when using Jetty. This example is pulled from the PetStore application.

@RestMethod( ... ) public SeeOtherRoot uploadFile(RestRequest req) throws Exception { // Required for Jetty. MultipartConfigElement mce = new MultipartConfigElement((String)null); req.setAttribute("org.eclipse.jetty.multipartConfig", mce); String id = UUID.randomUUID().toString(); BufferedImage img = null; for (Part part : req.getParts()) { switch (part.getName()) { case "id": id = IOUtils.read(part.getInputStream()); break; case "file": img = ImageIO.read(part.getInputStream()); } } addPhoto(id, img); return new SeeOtherRoot(); // Redirect to the servlet root. }