fix 点名未配置头像时缺少头像的bug

server-db/src/main/java/cn/exploring/engine/server/db/service/StudentInfoService.java

@@ -122,7 +122,7 @@ public class StudentInfoService {
         }
 
         increaseCallTimeByPrimaryKey(record.getId());
-        return record;
+        return updateHead(record);
     }
 
    /**
@@ -279,6 +279,16 @@ public class StudentInfoService {
         return list;
     }
 
+    public static <T extends StudentInfo> T updateHead(T record) {
+        if (Objects.nonNull(record) && (StringUtils.isBlank(record.getHead()) || StringUtils.equalsIgnoreCase(record.getHead(), STRING_DEFAULT_HEAD))) {
+            record.setHead(URL_DEFAULT_HEAD);
+        }
+
+        return record;
+    }
+
+
+
 //    /**
 //     * 查询可以被点名的学生名单
 //     * @param classId   班级ID