MessageQueryFlag

查询参考消息之前的消息，不包括参考消息

查询以参考消息为中心，前后一定数量的消息

查询参考消息之后的消息，不包括参考消息

Returns a representation of an immutable list of all enum entries, in the order they're declared.

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Returns an array containing the constants of this enum type, in the order they're declared.