converting DataHandler to byte[]

Question

I need a code snippt for converting DataHandler to byte[].

This data handler contains Image.

score 30 · Accepted Answer · edited Sep 17 '18 at 13:51

30

It can be done by using below code without much effort using apache IO Commons.

final InputStream in = dataHandler.getInputStream();
byte[] byteArray=org.apache.commons.io.IOUtils.toByteArray(in);

edited Sep 17 '18 at 13:51

giannis christofakis

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answered Jan 13 '11 at 11:17

Narendra

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score 13 · Answer 2 · answered Apr 20 '12 at 14:50

13

You can do it like this:

public static byte[] toBytes(DataHandler handler) throws IOException {
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    handler.writeTo(output);
    return output.toByteArray();
}

answered Apr 20 '12 at 14:50

Weihong Diao

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score 4 · Answer 3 · answered Jan 12 '11 at 17:28

private static final int INITIAL_SIZE = 1024 * 1024;
private static final int BUFFER_SIZE = 1024;

public static byte[] toBytes(DataHandler dh) throws IOException {
    ByteArrayOutputStream bos = new ByteArrayOutputStream(INITIAL_SIZE);
    InputStream in = dh.getInputStream();
    byte[] buffer = new byte[BUFFER_SIZE];
    int bytesRead;
    while ( (bytesRead = in.read(buffer)) >= 0 ) {
        bos.write(buffer, 0, bytesRead);
    }
    return bos.toByteArray();
}

Beware that ByteArrayOutputStream.toByteArray() creates a copy of the internal byte array.

score 2 · Answer 4 · answered Apr 10 '13 at 14:06

2

I use this code:

public static byte[] getContentAsByteArray(DataHandler handler) throws IOException {
    byte[] bytes = null;
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    handler.writeTo(bos);
    bos.flush();
    bos.close();
    bytes = bos.toByteArray();

    return bytes;
}

answered Apr 10 '13 at 14:06

matyig

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the close operation should be in a finally clause or you should use a Java 7 try catch. – Christophe Roussy Feb 24 '15 at 14:47

score 0 · Answer 5 · edited May 21 '15 at 12:02

0

Is something like this what you are looking for?

public static byte[] getBytesFromDataHandler(final DataHandler data) throws IOException {
    final InputStream in = data.getInputStream();
    byte out[] = new byte[0];
    if(in != null) {
        out = new byte[in.available()];
        in.read(out);
    } 
    return out;
}

UPDATE:

Based on dkarp's comment this is incorrect. According to the docs for InputStream:

Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream. The next caller might be the same thread or or another thread.

It looks like Costi has the correct answer here.

edited May 21 '15 at 12:02

Magnilex

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answered Jan 12 '11 at 17:21

Casey

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`InputStream.available()` is not appropriate for this purpose. The `PipedInputStream` returned from the `DataHandler` returns the number of bytes available in its buffer before it blocks, not the total size. – dkarp Jan 12 '11 at 17:27
Interesting. I've seen this code in many places when dealing with web services. – Casey Jan 12 '11 at 17:31

converting DataHandler to byte[]

5 Answers5