摘要：
以下引用官方描述：The FreeMarker template language doesn't know the Java language null at all. It doesn't have null keyword, and it can't test if something is null or not. 1.判断是否存在,通过exists关键字或者"??"运算符。都将返回一个布尔值user.name?existsuser.name??<#if user.name?exists> //TO DO</#if>& 阅读全文
