EF保存平面数据到SqlServer

前言 公司开展一个项目，需要根据客户手机定位获取周围内的精准广告，具体是管理员在地图上绘制多边形的广告范围，落在范围内的客户就看到此广告。下面将我的实现方法简单叙述一下，以供有相同需求的朋友参考。 EF平面对象DbGeometry DbGeometry可以表示点、

前言

公司开展一个项目，需要根据客户手机定位获取周围内的精准广告，具体是管理员在地图上绘制多边形的广告范围，落在范围内的客户就看到此广告。下面将我的实现方法简单叙述一下，以供有相同需求的朋友参考。

EF平面对象DbGeometry

DbGeometry可以表示点、线、多边形等平面对象，输入对象可以是WKT(Well-known text)，我们可以把百度地图上的polygon对象的点转换为多边形的wkt描述，再转为DbGeometry进行保存。

    <span>///</span> <span><summary></span>        <span>///</span><span> 从多点数据生成多边形        </span><span>///</span> <span></summary></span>        <span>///</span> <span></span><span>百度地图多边形的点集</span><span></span>        <span>public</span> <span>static</span> DbGeometry PolygonFromPointsJson(<span>string</span><span> pointsJson)        {            </span><span>var</span> points = JsonSerializer.ToEntity<List><span>(pointsJson);            </span><span>if</span> (points.First().GetHashCode() !=<span> points.Last().GetHashCode())            {                points.Add(points.First());            }            </span><span>var</span> closePoints = ((IEnumerable)points).Select(item => <span>string</span>.Format(<span>"</span><span>{0} {1}</span><span>"</span><span>, item.Lng, item.Lat));            </span><span>var</span> wkt = <span>"</span><span>POLYGON((</span><span>"</span> + <span>string</span>.Join(<span>"</span><span>,</span><span>"</span>, closePoints) + <span>"</span><span>))</span><span>"</span><span>;            </span><span>return</span><span> DbGeometry.PolygonFromText(wkt, SYSTEM_ID);        }</span>

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广告实体里用DbGeometry类型记录多边形范围

 <span>///</span> <span><summary></span>    <span>///</span><span> 广告范围表    </span><span>///</span> <span></summary></span><span>    [Serializable]    </span><span>public</span> <span>class</span><span> AdvRange : Entity    {        </span><span>///</span> <span><summary></span>        <span>///</span><span> 广告范围名        </span><span>///</span> <span></summary></span><span>        [Required]        [Length(</span><span>20</span><span>)]        </span><span>public</span> <span>string</span> Name { <span>get</span>; <span>set</span><span>; }        </span><span>///</span> <span><summary></span>        <span>///</span><span> 所属城市标识ID        </span><span>///</span> <span></summary></span>        <span>public</span> Guid CityId { <span>get</span>; <span>set</span><span>; }        </span><span>///</span> <span><summary></span>        <span>///</span><span> 多边形     </span><span>///</span> <span></summary></span>         <span>public</span> DbGeometry Polygon { <span>get</span>; <span>set</span><span>; }    }</span>

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从DbGeometry对象获取多边形的点

DbGeometry对象的WellKnownValue属性的可以获取WKT文本，目前我没有找到相关工具转WKT转为Json，所以用正则表达式获取也能满足需要，然后将结果转换为json就可以放到地图上进行展示了。

 <span>///</span> <span><summary></span>        <span>///</span><span> 获取多边形的点        </span><span>///</span> <span></summary></span>        <span>///</span> <span></span>        <span>public</span> <span>static</span> List GetPolygonPoints(<span>this</span><span> DbGeometry geometry)        {            </span><span>var</span> list = <span>new</span> List<span>();            </span><span>var</span> points = geometry.WellKnownValue.WellKnownText.Matches(<span>@"</span><span>-?[1-9]\d*\.\d*|-?0\.\d*[1-9]\d*</span><span>"</span>).Select(item => <span>decimal</span><span>.Parse(item)).ToArray();            </span><span>for</span> (<span>var</span> i = <span>0</span>; i < points.Length; i = i + <span>2</span><span>)            {                list.<i style="color:transparent">本文来源gaodai$ma#com搞$代*码*网(</i>Add(</span><span>new</span> LngLat { Lng = points[i], Lat = points[i + <span>1</span><span>] });            }            </span><span>if</span> (list.First().GetHashCode() ==<span> list.Last().GetHashCode())            {                list.RemoveAt(list.Count </span>- <span>1</span><span>);            }            </span><span>return</span><span> list;        }</span>

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广告范围是否包含客户位置的点

DbGeometry有很多方法和属性，EF可以将其翻译到对应的sql语句，其中Polygon.Intersects(point)可以判断点是否在多边形内。

效果图（中心的红标注为多边形的重心）

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