<users>
   <user name="xiaoming" pwd="123">boy</user>
   <user name="xiaohong" pwd="456">girl</user>
</users>

public String getValueFrmXML(String field)throws BtirException {
        String ret ="";
        if(null != xml && xml.trim().length()==0) throw new BtirException(
                BtirException.INVALID_DATA);
        String cXml = xml;
        
        int idx = cXml.indexOf(field+"/");
        if(idx>-1){
            return "";
        }
        if("SessionBody>".equals(field)){
            cXml = cXml.replaceAll("\\s", "");
            idx = cXml.indexOf(field);
        }else{
            idx = cXml.indexOf(field+">");
        }
        if(idx >-1){
            cXml = cXml.substring((idx+field.length()+1));
            int odx = cXml.indexOf("<");
            if(odx>-1){
                ret = cXml.substring(0,odx);
            }
        }
        return ret;    
    }