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Download multiple Android files in AppEngine in 1 request

I understand that I can upload 1 file at a time to AppEngine using POST requests for multi-page / forms. AppEngine also supports downloading multiple files , but you need to do some Jokky JSP stuff to work.

I have an application that requires me to upload some form data, 2 images and 3 text fields. Can this be done through AppEngine? I'm trying to find information about this, but it's hard for me to work with the flexibility that I need. I will store the data in the blob repository / repository.

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 the Java Servlet if you really need it. The above is the question and the corresponding servlet fragments.

 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
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1 answer

You can create your own multi-page file downloader , then save the files through the Blobstore FileService API .

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