Java (JDK only): Efficiently convert InputStream to String

InputStreamToString.java

private static String inputStreamToString(final InputStream is) throws IOException {
    final InputStreamReader ir = new InputStreamReader(is, "UTF-8");
    final StringBuilder sb = new StringBuilder();
    final char[] buf = new char[1024];
    int n;
    while ((n = ir.read(buf)) != -1) {
        sb.append(buf, 0, n);
    }
    return sb.toString();
}