@Override
  public int read() {
    if (this.buf.hasRemaining()) {
      return (this.buf.get() & 0xff);
    }
    return -1;
  }
Reads the next byte of data from this input stream. The value byte is returned as an
<code>int</code> in the range <code>0</code> to <code>255</code>. If no byte is available
because the end of the stream has been reached, the value <code>-1</code> is returned.
@return the next byte of data, or <code>-1</code> if the end of the stream has been reached.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/ByteBuffInputStream.java