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?

Answer 1

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();
}

Answer 2

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