public static int copy(Reader input, Writer output) throws IOException {
        long count = copyLarge(input, output);
        if (count > Integer.MAX_VALUE) {
            return -1;
        }
        return (int) count;
    }
Copy chars from a <code>Reader</code> to a <code>Writer</code>.
<p>
This method buffers the input internally, so there is no need to use a
<code>BufferedReader</code>.
<p>
Large streams (over 2GB) will return a chars copied value of
<code>-1</code> after the copy has completed since the correct
number of chars cannot be returned as an int. For large streams
use the <code>copyLarge(Reader, Writer)</code> method.

@param input  the <code>Reader</code> to read from
@param output the <code>Writer</code> to write to
@return the number of characters copied, or -1 if &gt; Integer.MAX_VALUE
@throws NullPointerException if the input or output is null
@throws IOException          if an I/O error occurs
@since 1.1
pay-java-common/src/main/java/com/egzosn/pay/common/util/IOUtils.java