解决方法也简单：

自定义个一个 Date2LongTypeHandler

    <resultMap id="BeanResult" type="XXXX.XXXXDO">
        <result column="gmt_create" property="gmtCreate" jdbcType="DATE" javaType="java.lang.Long"
                typeHandler="XXXX.Date2LongTypeHandler"/>
        <result column="gmt_modified" property="gmtModified" jdbcType="DATE" javaType="java.lang.Long"
                typeHandler="XXXXX.Date2LongTypeHandler"/>
    </resultMap>

Date2LongTypeHandler类实现如下：

public class Date2LongTypeHandler extends BaseTypeHandler<Long> {
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, Long date, JdbcType jdbcType) throws SQLException {
        ps.setDate(i, new java.sql.Date(date));
    }

    @Override
    public Long getNullableResult(ResultSet resultSet, String columnName) throws SQLException {
        return toLong(resultSet.getDate(columnName));
    }

    @Override
    public Long getNullableResult(ResultSet resultSet, int i) throws SQLException {
        return toLong(resultSet.getDate(i));
    }

    @Override
    public Long getNullableResult(CallableStatement cs, int i) throws SQLException {
        return toLong(cs.getDate(i));
    }

    private Long toLong(Date time) {
        if (time == null) {
            return null;
        }
        return time.getTime();
    }
}