简单的Map转成XML

public static String toXml(Map<String, String> params){
        StringBuilder buf = new StringBuilder();
        List<String> keys = new ArrayList<String>(params.keySet());
        Collections.sort(keys);
        buf.append("<xml>");
        for(String key : keys){
            buf.append("<").append(key).append(">");
            buf.append("<").append(params.get(key)).append(">");
            buf.append("</").append(key).append(">\n");
        }
        buf.append("</xml>");
        return buf.toString();
    }public static String toXml(Map<String, St