字节转换字符

private static String convertStreamToString(InputStream is,String s) {    try {

        InputStreamReader isr=new InputStreamReader(is,s);

        BufferedReader br=new BufferedReader(isr);

        String ss=null;

        StringBuilder sb=new StringBuilder();        while((ss=br.readLine())!=null){            sb.append(ss);        }        br.close();        return sb.toString();    } catch (Exception e) {        e.printStackTrace();    }    return null;}