fix:bug修改

im-common/src/main/java/com/bx/imcommon/contant/IMRedisKey.java

@@ -11,6 +11,10 @@ public final class IMRedisKey {
      * 用户ID所连接的IM-server的ID
      */
     public static final String  IM_USER_SERVER_ID = "im:user:server_id";
+    /**
+     * 用户最后活跃时间，hash field 为用户ID，value 为毫秒时间戳
+     */
+    public static final String IM_USER_LAST_ACTIVE = "im:user:last_active";
     /**
      * 系统消息队列
      */