Upload multiple files from Android to AppEngine in 1 request

Question

I understand that I can upload 1 file at a time to AppEngine using multipart/form POST requests. AppEngine also supports uploading multiple files but you have to do some hokey JSP stuff for it to work.

I have an app that requires me to upload some form data, 2 images and 3 fields of text. Is this possible to do via AppEngine? I've been trying to find information on this but it's tough nothing works with the flexibility I need. I will be storing the data in the blob store/data store.

I need a Java solution.

This is the signature of my POST method:

import javax.ws.rs.Consumes;
import javax.ws.rs.POST;

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
public void post(
       @Context HttpServletRequest request,
       @Context HttpServletResponse response)
       throws FileUploadException, IOException {}

Copy and paste of the Java Servlet if you really need it. Above is the question and relevant servlet snippets.

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.util.Iterator;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;

import org.apache.commons.fileupload.FileItemHeaders;
import org.apache.commons.fileupload.FileItemIterator;
import org.apache.commons.fileupload.FileItemStream;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.google.appengine.api.blobstore.BlobstoreService;
import com.google.appengine.api.blobstore.BlobstoreServiceFactory;
import com.google.appengine.api.files.AppEngineFile;
import com.google.appengine.api.files.FileReadChannel;
import com.google.appengine.api.files.FileService;
import com.google.appengine.api.files.FileServiceFactory;
import com.google.appengine.api.files.FileWriteChannel;

@Path("/upload")
public class FileUploadServlet {

    private BlobstoreService blobstoreService = BlobstoreServiceFactory
            .getBlobstoreService();

    @POST
    @Consumes(MediaType.MULTIPART_FORM_DATA)
    public void post(@Context HttpServletRequest request,
            @Context HttpServletResponse response) throws FileUploadException,
            IOException {

        final ServletFileUpload upload = new ServletFileUpload();
        final FileItemIterator fileIter = upload.getItemIterator(request);

        while (fileIter.hasNext()) {
            final FileItemStream item = fileIter.next();
            String name = item.getName();
            String fieldName = item.getFieldName();
            String contentType = item.getContentType();
            Log.d("Name  =  " + name);
            Log.d("Field-Name  =  " + fieldName);
            Log.d("Content-Type  =  " + contentType);
            FileItemHeaders headers = item.getHeaders();
            if(headers != null) {
                Iterator<String> it = (Iterator<String>)headers.getHeaderNames();
                while(it.hasNext()) {
                    String h = it.next();
                    Log.d(h + "  =  " + headers.getHeader(h));
                }
            }
            if (item.isFormField()) {
                // Nothing
            } else {
                RawImageData data = new RawImageData();
                data.load(item.openStream());
                            // RawImageData reads the stream and stores it into a large byte[] called data.imageData
                ByteBuffer bb = ByteBuffer.wrap(data.imageData);
                FileService fs = FileServiceFactory.getFileService();
                AppEngineFile file = fs.createNewBlobFile(contentType);
                FileWriteChannel write = fs.openWriteChannel(file, true);

                write.write(bb);
                write.closeFinally();
                String path = file.getFullPath();
                Log.d(path);

                // Later, read from the file using the file API
                boolean lock = false; // Let other people read at the same time
                FileReadChannel readChannel = fs.openReadChannel(file,
                        false);
                            // CRASHES WITH java.nio.charset.IllegalCharsetNameException: image/jpeg
                            // contentType = "image/jpeg"
                // Again, different standard Java ways of reading from the
                // channel.
                BufferedReader reader = new BufferedReader(Channels.newReader(readChannel, contentType));

                readChannel.close();
            }
        }

        response.setContentType("text/html");
        response.getOutputStream().write("success".getBytes());
    }
}

Full Exception:

WARNING: /api/upload
java.nio.charset.IllegalCharsetNameException: image/jpeg
    at java.nio.charset.Charset.checkName(Charset.java:284)
    at java.nio.charset.Charset.lookup2(Charset.java:458)
    at java.nio.charset.Charset.lookup(Charset.java:437)
    at java.nio.charset.Charset.forName(Charset.java:502)
    at java.nio.channels.Channels.newReader(Channels.java:381)
    at com.futonredemption.starstarstar.FileUploadServlet.post(FileUploadServlet.java:96)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    blah blah blah

Answer 1

You can create you own multipart file upload handler, then save files via Blobstore FileService API.