FreeMarker空值异常：

freemarker 报错： username:'FreeMarker template error (DEBUG mode; use RETHROW in production!): The following has evaluated to null or missing: ==> profile [in template “inc/layout.ftl” at line 28, column 21] Tip: If the failing expression is known to legally refer to something that’s sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??

大致意思是某个对象为null或者缺失，导致表达式不合法，可以指定默认值，指定方式是：myOptionalVar!myDefault 或者<#if myOptionalVar??>when-present<#else>when-missing</#if>. （这仅仅覆盖最后一个表达式，如果要覆盖整个表达式使用：(myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??） 我的错误在：

<script> layui.cache.user = { username:'${profile.username!"游客"}' ,uid:${profile.id!"-1"} ,avatar: '${profile.avatar!"/res/images/avatar/00.jpg"}' ,experience: 83 ,sex: '${profile.sex!"男"}' }; </script>

提示==> profile [in template “inc/layout.ftl” at line 28, column 21]为空，于是修改为带括号的表达式解决问题：

<script> layui.cache.user = { username:'${(profile.username)!"游客"}' ,uid:${(profile.id)!"-1"} ,avatar: '${(profile.avatar)!"/res/images/avatar/00.jpg"}' ,experience: 83 ,sex: '${(profile.sex)!"男"}' }; </script>

不在报错，解决问题。