import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.io.ByteArrayInputStream;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamReader;

public class TestXmlReader {
	private static final int BYTES_PER_READ = 6; 

	private static final String XML = 
			"<?xml version=\"1.0\" encoding=\"UTF-8\"?>" + 
					"<He likes=\"rugs\" because=\"they really tie the room together\"/>"; 

	public static void main(String[] args) throws Exception { 
		final InputStream xmlStream = new ByteArrayInputStream(XML.getBytes(Charset.forName("UTF-8"))); 
		final InputStream throttledXmlStream = new ThrottledInputStream(xmlStream, BYTES_PER_READ); 

		final XMLInputFactory xmlFactory = XMLInputFactory.newInstance(); 
		final XMLStreamReader xmlStreamReader = xmlFactory.createXMLStreamReader(throttledXmlStream); 
		xmlStreamReader.next(); 

		// bugs or rugs? 
		System.out.println(xmlStreamReader.getAttributeValue(null, "likes")); 
	} 

	// An InputStream implementation that limits the number of bytes read by read(byte[], int, int) 
	private static class ThrottledInputStream extends FilterInputStream { 
		private final int bytesPerRead; 

		public ThrottledInputStream(InputStream stream, int bytesPerRead) throws Exception { 
			super(stream); 
			this.bytesPerRead = bytesPerRead; 
		} 

		@Override 
		public int read(byte[] b, int off, int len) throws IOException { 
			if (off < 0 || len < 0 || len > b.length - off) { 
				throw new IndexOutOfBoundsException(); 
			} else if (len == 0) { 
				return 0; 
			} 

			// Limit bytes read 
			int bytesToRead = Math.min(bytesPerRead, len); 

			// Ensure deterministic behavior (similar to org.apache.commons.io.IOUtils.read) 
			// Useless for this test case, but convenient for consistently reproducing 
			// the bug with other stream implementations 
			int totalBytesRead = 0; 
			int bytesRead = 0; 
			do { 
				bytesRead = Math.max(0, in.read(b, off + totalBytesRead, bytesToRead)); 
				bytesToRead -= bytesRead; 
				totalBytesRead += bytesRead; 
			} while (bytesRead > 0); 

			// No more bytes 
			if (totalBytesRead == 0) { 
				return -1; 
			} 

			return totalBytesRead; 
		} 
	} 
}