增加公共方法

njcn-db/mybatis-plus/src/main/java/com/njcn/db/mybatisplus/constant/UserConstant.java

@@ -6,5 +6,7 @@ public interface UserConstant {
 
     String UNKNOWN_USER_ID = "未知用户";
 
+    String UN_LOGIN = "未登录用户";
+
     String USER_NAME = "userName";
 }