ByteBuffer to byte array

Question

I have a ByteBuffer, and I need to add its content to a POST request in order to remotely display the image which represents; but I can't figure it out how to do it.

Doing this doesn't work:

byteBuffer.array()

I have tried to convert it to an array of bytes, but it didn't work because the image wasn't showing properly:

byte[] byteArray = new byte[byteBuffer.remaining()];
frame.duplicate().get(byteArray);
HttpResponse response = null;
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(URL);
post.setEntity(new ByteArrayEntity(byteArray));

Also I've think about converting it to an image and get its array of bytes but I don't know how to do it and if it would work...

Any help will be appreciate.

No, byteBuffer.array() does not form the image correctly, and if I debug the app the result of doing so is an array in which each element is a 0 value... — svprdga
– svprdga, Commented Mar 9, 2015 at 10:53
Then either you haven't read anything into it or you haven't debugged cirrextly. — user207421
– user207421, Commented Mar 9, 2015 at 10:55
@svprdga Show us how you populate the byte buffer. Chances are, the error is there. — Duncan Jones
– Duncan Jones, Commented Mar 9, 2015 at 10:55
@EJP: From the documentation of ByteBuffer.array(): "Returns the byte array which this buffer is based on, if there is one", maybe my ByteBuffer has been made in some other way....?? — svprdga
– svprdga, Commented Mar 9, 2015 at 11:07

Salman Nazir · Accepted Answer · 2017-10-10 17:01:24Z

6

private static byte[] getByteArrayFromByteBuffer(ByteBuffer byteBuffer) {
    byte[] bytesArray = new byte[byteBuffer.remaining()];
    byteBuffer.get(bytesArray, 0, bytesArray.length);
    return bytesArray;
}

answered Oct 10, 2017 at 17:01

Salman Nazir

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Joop Eggen · Accepted Answer · 2015-03-09 11:14:34Z

3

A ByteBuffer created with allocate (not necessarily allocateDirect) should have a backing array, check with hasArray() / isDirect().

byteBuffer.flip();  // Sets limit to current write position.
int n = byteBuffer.limit();
byteBuffer.rewind(); // Already done by flip I think.
byte[] data = new byte[n];
byteBuffer.get(data);

answered Mar 9, 2015 at 11:14

Joop Eggen

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1 Comment

svprdga Over a year ago

hasArray() returns false. I have tried your code, byteBuffer.limit() returns 0 and the final data array has 0 lenght...

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