Question

Am uploading a mutlipart file to Google app engine using the below shown code. With the help of apache commons file uploader am uploading the file to Google app engine successfully. I want to validate the file size if it is 0 bytes or not. To do this i verified the Google app engine and the apache commons file uploader to check the file size but i got failed. Do we have any methods to find the file size. Kindly suggest me an idea.

My Servlet

ServletFileUpload upload = new ServletFileUpload();
FileItemIterator iter;
iter = upload.getItemIterator(request);
while (iter.hasNext()) {
item = iter.next();
String fileName =  item.getName();
String fieldName = item.getFieldName();
if (item.isFormField()) {
String fieldValue = Streams.asString(item.openStream());
}
InputStream is1 = item.openStream();
try {
FileService fileService = FileServiceFactory.getFileService();
AppEngineFile file = fileService.createNewBlobFile(mime, fileName);
boolean lock = true;
 FileWriteChannel writeChannel = fileService.openWriteChannel(file, lock);
 byte[] b1 = new byte[BUFFER_SIZE];
int readBytes1;
while ((readBytes1 = is1.read(b1)) != -1) {
 writeChannel.write(ByteBuffer.wrap(b1, 0, readBytes1));
}
writeChannel.closeFinally();

Answer 1

You need to read the whole is1 input stream into a byte buffer and see it’s length. You can use this snippet:

public static byte[] getBytes(InputStream is) throws IOException {
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();

    int len;
    byte[] data = new byte[10000];
    while ((len = is.read(data, 0, data.length)) != -1) {
        buffer.write(data, 0, len);
    }

    buffer.flush();
    return buffer.toByteArray();
}