java利用反射机制判断对象的属性是否为空

java利用反射机制判断对象的属性是否为空：

Map<String,String> validateMap = new LinkedHashMap<String, String>();

validateMap.put("serial", "编号");
validateMap.put("major", "专业");

public static <T> String validateFiledIsNull(Map<String,String> fileds,T obj) throws Exception{
   String ret ="";
   for(String key:fileds.keySet()){
      String getMethodStr = "get" + key.substring(0,1).toUpperCase()+key.substring(1);
      Method m = obj.getClass().getMethod(getMethodStr);
      Object value =  m.invoke(obj);
      if(value==null || value.toString().trim().equals("")){
         if(!validateString(ret)){
            ret=fileds.get(key);
         }else{
            ret+=","+fileds.get(key);
         }
      }
   }
   return ret;
}