inputstream转String (rocketmq)

    static public String toString(InputStream input, String encoding) throws IOException {
        return (null == encoding) ? toString(new InputStreamReader(input, "UTF-8")) : toString(new InputStreamReader(
                input, encoding));
    }
    static public String toString(Reader reader) throws IOException {
        CharArrayWriter sw = new CharArrayWriter();
        copy(reader, sw);
        return sw.toString();
    }
    static public long copy(Reader input, Writer output) throws IOException {
        char[] buffer = new char[1 << 12];
        long count = 0;
        for (int n = 0; (n = input.read(buffer)) >= 0; ) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }