In Java, how can I convert an InputStream into a byte array (byte[])?

Question

My background is .net, I'm fairly new to Java. I'm doing some work for our company's java team and the architect needs me to implement a method that takes an InputStream (java.io) object. In order to fulfill the method's purpose I need to convert that into a byte array. Is there an easy way to do this?

Be aware that this may be memory hogging. – BalusC Jan 29 '10 at 17:18 — BalusC, Jan 29 '10 at 17:18

score 61 · Accepted Answer · answered Jan 29 '10 at 17:12

61

The simplest way is to create a new ByteArrayOutputStream, copy the bytes to that, and then call toByteArray:

public static byte[] readFully(InputStream input) throws IOException
{
    byte[] buffer = new byte[8192];
    int bytesRead;
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    while ((bytesRead = input.read(buffer)) != -1)
    {
        output.write(buffer, 0, bytesRead);
    }
    return output.toByteArray();
}

answered Jan 29 '10 at 17:12

Jon Skeet

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Make sure you flush the outputstream before returning. – quikchange May 20 '10 at 14:17
5

@quikchange: There's no need when you're using a ByteArrayOutputStream - where would it buffer to? – Jon Skeet May 20 '10 at 14:41

score 9 · Answer 2 · answered Jan 29 '10 at 17:13

9

A simple way would be to use org.apache.commons.io.IOUtils.toByteArray( inputStream ), see apache commons io.

answered Jan 29 '10 at 17:13

tangens

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In Java, how can I convert an InputStream into a byte array (byte[])?

2 Answers2

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