签名加密ascii排序例子

public static String sign(String secret,Map<String,String> params){        //按参数名asscic码排序        List<String> names=new ArrayList();        names.addAll(params.keySet());        java.util.Collections.sort(names);        String strSign = secret;        for(String key:names)            strSign+=key+params.get(key);        strSign+=secret;        return MD5(strSign).toUpperCase();    }