GIS前端将选中的图形输出为Shapfile文件

老师让我实现如题的功能，我对着ArcGIS js api找了半天，没有发现该方法接口，找了很多资料，前后问了三个前辈。

第一个前辈说用GP服务，我在ArcMap的工具箱里找到convert to layerfile这个功能，试过之后。发现该方法的不足之处在于①只能输出整张图层，我希望能选择任意的部分输出②发布成GP服务后，只能控制输入参数（输入的图层），而输出参数（输出的文件名）不能控制。该方法GG。

第二个前辈说，将查询出来的实体写进gdb里。我就找啊找，找啊找，没找到api有这个功能。

后来自己分析查询出来的graphics，分析其dom组成部分，意外的发现，存在attributes和gepmetry两个部分，又发现ArcMap的工具箱里存在JSON TO Feature和Feature  TO JSON两个功能，似乎可以搞点事情出来。此时，正好遇到第三个前辈，我跟他提出了我的问题以及自己的想法，认可了我的观点，并指出不要用现成的工具箱发布GP服务来转，会有问题，用Arcengine二次开发，自己解析。我可是想偷懒的人，放着GP服务不用是不是有点可惜，试了下，ArcMap将点转出为JSON，再将JSON转为点没问题，而转线和面时，问题就出来了，能转出JSON，而不能再将JSON转回去。前辈诚不欺我。

好了，不说废话了，下面介绍我的解决方法，分四步：①graphics转JSON ②JSON转Geometry ③Geometry转Feature ④Feature输出为Shapfile

一、graphics转JSON

我的graphics只有三种简单类型，point，polyline，polygon，拼接字符串的时候要细心，下面是我的代码

 //created by YS 20171218

 //判断属性值是字符串？整型？浮点型？
 //返回对应于esri的值类型
 function checkValueType(value) {
     if (/^-?\d*\.\d+$/.test(value))//是否浮点型
         return "esriFieldTypeDouble";
     else if (/^\d+$/.test(value))//是否整型
         return "esriFieldTypeInteger";
     else
         return "esriFieldTypeString";//字符串型

 }
 //******参数类型 graphic集合，必须是单一的点或线或面类型
 //******输出类型 json
 function convertToJson(graphics) {
     var attributes = graphics[0].attributes;//取得属性
     //取得属性名
     var attributes_name = [];
     for (var key in attributes) {
         //排除attributes.SHAPE
         if (key.toUpperCase() == "SHAPE")
             continue;
         attributes_name.push(key);
     }

     //判断geometryType类型
     var geometryType = "";
     switch (graphics[0].geometry.type) {
         case "polygon":
             geometryType = "esriGeometryPolygon";
             break;
         case "polyline":
             geometryType = "esriGeometryPolyline";
             break;
         case "point":
             geometryType = "esriGeometryPoint";
             break;
         default: break;
     }
     //
     //获取spatialReference
     var spatialReference = $.toJSON(graphics[0].geometry.spatialReference);

     //判断属性值类型
     var attributes_valueType = [];
     for (var j = 0; j < attributes_name.length; j++) {
         attributes_valueType[j] = checkValueType(graphics[0].attributes[attributes_name[j]]);
     }

     //准备属性名和属性类型
     var fields = "";

     for (var i = 0; i < graphics.length; i++) {
         var field = "";
         for (var j = 0; j < attributes_name.length; j++) {

             if (attributes_valueType[j] == "esriFieldTypeString") {//字符串型字段比其他类型多一个长度属性
                 var obj = new Object();
                 obj.name = attributes_name[j];
                 obj.type = attributes_valueType[j];
                 obj.alias = attributes_name[j];
                 obj.length = "50";
                 field += $.toJSON(obj) + ",";
             } else {
                 var obj = new Object();
                 obj.name = attributes_name[j];
                 obj.type = attributes_valueType[j];
                 obj.alias = attributes_name[j];
                 field += $.toJSON(obj) + ",";
             }
         }
     }
     //去掉最后一个逗号
     field = field.substring(0, field.length - 1);
     //拼接fields
     //***********arcmap将要素转json时，输出数据中有FID*********************************************
     //***********该json通过ArcEngine转为shapfile时，不需要拼接FID***********************************
     //var fields = "{\"name\":\"FID\",\"type\":\"esriFieldTypeOID\",\"alias\":\"FID\"}," + field;
     var fields = field;

     //准备features(attributes+geometry)
     var features = "";
     var attributes = [];
     var geometry = [];
     //*******比下面注释掉的程序省掉多次循环判断，降低时间复杂度*****
     if (geometryType == "esriGeometryPolygon") {
         for (var i = 0; i < graphics.length; i++) {
             //删除“SHAPE”属性
             var attr = graphics[i].attributes;
             //SHAPE大小写不确定
             delete attr.SHAPE;
             delete attr.Shape;
             attributes[i] = $.toJSON(attr);
             //组织面的geometry
             geometry[i] = $.toJSON(graphics[i].geometry.rings);
             features += "{\"attributes\":" + attributes[i] + ",\"geometry\":{\"rings\":" + geometry[i] + "}},";
         }
     } else if (geometryType == "esriGeometryPolyline") {
         for (var i = 0; i < graphics.length; i++) {
             //删除“SHAPE”属性
             var attr = graphics[i].attributes;
             //SHAPE大小写不确定
             delete attr.SHAPE;
             delete attr.Shape;
             attributes[i] = $.toJSON(attr);
             //组织线的geometry
             geometry[i] = $.toJSON(graphics[i].geometry.paths);
             //如果需要将得到的 线json转成geoJson
             //path转json后，去掉最外层的中括号[]
             //geometry[i] = geometry[i].substring(1, geometry[i].length - 1);

             features += "{\"attributes\":" + attributes[i] + ",\"geometry\":{\"paths\":" + geometry[i] + "}},";
         }
     } else {
         for (var i = 0; i < graphics.length; i++) {
             //删除“SHAPE”属性
             var attr = graphics[i].attributes;
             //SHAPE大小写不确定
             delete attr.SHAPE;
             delete attr.Shape;
             attributes[i] = $.toJSON(attr);
             //组织点的geometry
             var geo = new Object();
             geo.x = graphics[i].geometry.x;
             geo.y = graphics[i].geometry.y;
             var geo = $.toJSON(geo);
             features += "{\"attributes\":" + attributes[i] + ",\"geometry\":" + geo + "},";
         }
     }

     //去掉最后一个逗号
     features = features.substring(0, features.length - 1);

     //拼接fieldAliases
     var fieldAliases = "";
     for (var i = 0; i < attributes_name.length; i++) {
         fieldAliases += "\"" + attributes_name[i] + "\":\"" + attributes_name[i] + "\",";
     }
     //去掉最后一个逗号
     fieldAliases = fieldAliases.substring(0, fieldAliases.length - 1);

     //拼接地图实体Json

     //var Json = "{\"displayFieldName\":\"\",\"fieldAliases\":{\"FID\":\"FID\"," + fieldAliases + "},\"geometryType\":\"" + geometryType + "\",\"spatialReference\":" + spatialReference + ",\"fields\":[" + fields + "],\"features\":[" + features + "]}";
     var Json = "{\"displayFieldName\":\"\",\"fieldAliases\":{" + fieldAliases + "},\"geometryType\":\"" + geometryType + "\",\"spatialReference\":" + spatialReference + ",\"fields\":[" + fields + "],\"features\":[" + features + "]}";

     //console.log(Json);
     return Json;
 }

二、JSON转Geometry

接下来的部分就属于ArcEngine二次开发了，已经有一年没碰过它了，捡起来心真累。

ArcEngine提供了JSONConverterGeometryClass接口，用于geometry字符串转geometry对象

 class jsonToGeo
     {
         /// <summary>
         /// 将json字符串转成动态对象
         /// </summary>
         /// <param name="json"></param>
         /// <returns></returns>
         public dynamic convert(string json)
         {
             var DynamicObject = JsonConvert.DeserializeObject<dynamic>(json);
             return DynamicObject;

         }

         /// <summary>
         /// JSON字符串转成IGeometry
         /// </summary>
         public ESRI.ArcGIS.Geometry.IGeometry GeometryFromJsonString(string strJson, ESRI.ArcGIS.Geometry.esriGeometryType type)
         {
             return GeometryFromJsonString(strJson, type, false, false);
         }

         /// <summary>
         /// JSON字符串转成IGeometry
         /// </summary>
         public ESRI.ArcGIS.Geometry.IGeometry GeometryFromJsonString(string strJson, ESRI.ArcGIS.Geometry.esriGeometryType type,
             bool bHasZ, bool bHasM)
         {
             ESRI.ArcGIS.esriSystem.IJSONReader jsonReader = new ESRI.ArcGIS.esriSystem.JSONReaderClass();
             jsonReader.ReadFromString(strJson);

             ESRI.ArcGIS.Geometry.JSONConverterGeometryClass jsonCon = new ESRI.ArcGIS.Geometry.JSONConverterGeometryClass();
             return jsonCon.ReadGeometry(jsonReader, type, bHasZ, bHasM);
         }
         /// <summary>
         /// IGeometry转成JSON字符串
         /// </summary>
         public string GeometryToJsonString(ESRI.ArcGIS.Geometry.IGeometry geometry)
         {
             ESRI.ArcGIS.esriSystem.IJSONWriter jsonWriter = new ESRI.ArcGIS.esriSystem.JSONWriterClass();
             jsonWriter.WriteToString();

             ESRI.ArcGIS.Geometry.JSONConverterGeometryClass jsonCon = new ESRI.ArcGIS.Geometry.JSONConverterGeometryClass();
             jsonCon.WriteGeometry(jsonWriter, null, geometry, false);

             return Encoding.UTF8.GetString(jsonWriter.GetStringBuffer());
         }

     }

解析JSON，先将其转成JSON对象，提取出List<IGeometry>

  /// <summary>
         /// 将JSON字符串转成Shapfile文件
         /// </summary>
         /// <param name="json">输入的Json字符串</param>
         /// <param name="outputFileFolder">输出的文件地址</param>
         /// <param name="ShapeName">输出的文件名（不带后缀）</param>
         public static void JsonToShp(string json, string outputFileFolder, string ShapeName)
         {
             //将json字符串转成动态对象
             jsonToGeo jTG = new jsonToGeo();
             var obj = jTG.convert(json);

             //获取json中的features集
             var features = obj["features"];
             int count = obj["features"].Count;//图形个数
             //obj["features"][0]["geometry"]表示第一个图形的geometry

             //坐标系
             int wkid = (int)obj["spatialReference"]["wkid"];

             //创建SpatialReferenceEnvironmentClass对象
             ISpatialReferenceFactory2 pSpaRefFactory = new SpatialReferenceEnvironmentClass();
             //创建地理坐标系对象
             //IGeographicCoordinateSystem pNewGeoSys = pSpaRefFactory.CreateGeographicCoordinateSystem(gcsType);//4214代表Beijing1954
             //创建投影坐标系
             IProjectedCoordinateSystem pGeoSys = pSpaRefFactory.CreateProjectedCoordinateSystem(wkid);//2437 Beijing_1954_3_Degree_GK_CM_120E 

             //字段集合
             var fields = obj["fields"];
             dynamic shpFields;
             shpFields = fields;

             //List<IPoint> points = new List<IPoint>();
             //List<IPolyline> polylines = new List<IPolyline>();
             //List<IPolygon> polygons = new List<IPolygon>();

             List<IGeometry> geometryList = new List<IGeometry>();

             GeoToFeature gtf = new GeoToFeature();

             string geometryType = obj["geometryType"].ToString();
             switch (geometryType)
             {
                 case "esriGeometryPoint":
                     for (int i = ; i < count; i++)
                     {
                         IPoint pointLocation = null;
                         pointLocation = jTG.GeometryFromJsonString(features[i]["geometry"].ToString(), ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPoint) as ESRI.ArcGIS.Geometry.IPoint;
                         pointLocation.SpatialReference = pGeoSys;
                         IGeometry point = pointLocation as IGeometry;
                         //points.Add(pointLocation);
                         geometryList.Add(point);
                     }
                     //创建点shp，并添加字段
                     gtf.CreateShapefile(outputFileFolder, ShapeName, esriGeometryType.esriGeometryPoint, pGeoSys, shpFields);

                     break;
                 case "esriGeometryPolyline":
                     for (int i = ; i < count; i++)
                     {
                         IPolyline polylineLocation = jTG.GeometryFromJsonString(features[i]["geometry"].ToString(), ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPolyline) as IPolyline;
                         polylineLocation.SpatialReference = pGeoSys;
                         IGeometry polyline = polylineLocation as IGeometry;
                         //polylines.Add(polylineLocation);
                         geometryList.Add(polyline);
                     }
                     //创建线shp，并添加字段
                     gtf.CreateShapefile(outputFileFolder, ShapeName, esriGeometryType.esriGeometryPolyline, pGeoSys, shpFields);
                     break;
                 case "esriGeometryPolygon":
                     for (int i = ; i < count; i++)
                     {
                         IPolygon polygonLocation = jTG.GeometryFromJsonString(features[i]["geometry"].ToString(), ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPolygon) as IPolygon;
                         polygonLocation.SpatialReference = pGeoSys;
                         IGeometry polygon = polygonLocation as IGeometry;
                         //polygons.Add(polygonLocation);
                         geometryList.Add(polygon);
                     }
                     //创建面shp，并添加字段
                     gtf.CreateShapefile(outputFileFolder, ShapeName, esriGeometryType.esriGeometryPolygon, pGeoSys, shpFields);

                     break;
                 default: break;
             }

             //添加要素
             gtf.AddFeatureByBuffer(outputFileFolder, ShapeName, geometryList, features);
         }

三、创建Shapfile文件

 /// <summary>
         /// 创建 shapfile文件并添加字段
         /// </summary>
         /// <param name="strShapeFolder">存放地址</param>
         /// <param name="strShapeName">文件名</param>
         /// <param name="geoType">几何类型</param>
         /// <param name="geoSys">坐标系统</param>
         /// <param name="shpFields">字段集</param>
         public void CreateShapefile(string strShapeFolder, string strShapeName, esriGeometryType geoType, IProjectedCoordinateSystem geoSys, dynamic shpFields)
         {
             //打开工作空间
             const string strShapeFieldName = "shape";
             IWorkspaceFactory pWSF = new ShapefileWorkspaceFactoryClass();
             IFeatureWorkspace pWS = (IFeatureWorkspace)pWSF.OpenFromFile(strShapeFolder, );

             //如果已存在,那么删除
             //IFeatureClass pFCChecker = pWS.OpenFeatureClass(strShapeName);
             //if (pFCChecker != null)
             //{
             //    IDataset pds = pFCChecker as IDataset;
             //    pds.Delete();
             //}

             //设置字段集
             IFields pFields = new FieldsClass();
             IFieldsEdit pFieldsEdit = (IFieldsEdit)pFields;

             //设置字段
             IField pField = new FieldClass();
             IFieldEdit pFieldEdit = (IFieldEdit)pField;

             //创建类型为几何类型的字段
             pFieldEdit.Name_2 = strShapeFieldName;
             pFieldEdit.Type_2 = esriFieldType.esriFieldTypeGeometry;

             //为esriFieldTypeGeometry类型的字段创建几何定义，包括类型和空间参照
             IGeometryDef pGeoDef = new GeometryDefClass();     //The geometry definition for the field if IsGeometry is TRUE.
             IGeometryDefEdit pGeoDefEdit = (IGeometryDefEdit)pGeoDef;
             //图形的类型
             //pGeoDefEdit.GeometryType_2 = esriGeometryType.esriGeometryPoint;
             pGeoDefEdit.GeometryType_2 = geoType;
             //pGeoDefEdit.SpatialReference_2 = new UnknownCoordinateSystemClass();
             pGeoDefEdit.SpatialReference_2 = geoSys;

             pFieldEdit.GeometryDef_2 = pGeoDef;
             pFieldsEdit.AddField(pField);

             for (int i = ; i < shpFields.Count; i++)
             {
                 string type = shpFields[i]["type"].ToString();
                 esriFieldType esriType = new esriFieldType();
                 switch (type)
                 {
                     case "esriFieldTypeDouble":
                         esriType = esriFieldType.esriFieldTypeDouble;
                         break;
                     case "esriFieldTypeInteger":
                         esriType = esriFieldType.esriFieldTypeInteger;
                         break;
                     case "esriFieldTypeString":
                         esriType = esriFieldType.esriFieldTypeString;
                         break;
                     default: break;

                 }
                 pField = new FieldClass();
                 pFieldEdit = (IFieldEdit)pField;
                 //arcgis的字段名最多十个字节，十个字母或五个汉字，多出来的部分不显示，而且乱码
                 pFieldEdit.Name_2 = GetSubString(shpFields[i]["name"].ToString(), );
                 pFieldEdit.Type_2 = esriType;
                 pFieldsEdit.AddField(pField);
             }

             //创建shapefile
             try
             {
                 pWS.CreateFeatureClass(strShapeName, pFields, null, null, esriFeatureType.esriFTSimple, strShapeFieldName, "");
             }
             catch (Exception e)
             {
                 //报错的话，说明有同名文件，再次执行能自动删除
                 throw e;
             }

         }

这里有一坑，ArcGIS的字段名最多只支持十个字节，如果添加字段时没有注意到这一点，那么接下来你是无法插入属性的

为此，我准备了截取字符串前n个字节的方法

 ///由于ArcGIS的字段最多十个字节，所以只能10字节以内
         /// </summary>
         /// <param name="origStr">原始字符串</param>
         /// <param name="endIndex">提取前endIdex个字节</param>
         /// <returns></returns>
         public string GetSubString(string origStr, int endIndex)
         {
             if (origStr == null || origStr.Length ==  || endIndex < )
                 return "";
             int bytesCount = System.Text.Encoding.GetEncoding("gb2312").GetByteCount(origStr);
             if (bytesCount > endIndex)
             {
                 int readyLength = ;
                 int byteLength;
                 for (int i = ; i < origStr.Length; i++)
                 {
                     byteLength = System.Text.Encoding.GetEncoding("gb2312").GetByteCount(new char[] { origStr[i] });
                     readyLength += byteLength;
                     if (readyLength == endIndex)
                     {
                         origStr = origStr.Substring(, i + );
                         break;
                     }
                     else if (readyLength > endIndex)
                     {
                         origStr = origStr.Substring(, i);
                         break;
                     }
                 }
             }
             return origStr;
         }

四、将要素写入创建的Shapfile中

 /// <summary>
         /// 向工作空间添加要素
         /// </summary>
         /// <param name="strShapeFolder">文件路径</param>
         /// <param name="strShapeName">文件名</param>
         /// <param name="geometryList">几何图形集</param>
         /// <param name="objJsonFeatures">json中的feature对象</param>
         public void AddFeatureByBuffer(string strShapeFolder, string strShapeName, List<IGeometry> geometryList, dynamic objJsonFeatures)
         {
             //利用缓存向shapefile文件中插入feature
             //当数据量较大时，IFeatureClass.CreateFeatureBuffer 比 IFeatureClass.CreateFeature 快

             //打开工作空间
             IWorkspaceFactory pWSF = new ShapefileWorkspaceFactoryClass();
             IFeatureWorkspace pWS = (IFeatureWorkspace)pWSF.OpenFromFile(strShapeFolder, );

             //添加要素
             IFeatureClass featureClass = pWS.OpenFeatureClass(strShapeName);

             IFeatureCursor featureCursor = featureClass.Insert(true);
             IFeatureBuffer featureBuffer = featureClass.CreateFeatureBuffer();

             int i = ;
             foreach (IGeometry geometry in geometryList)
             {
                 //给每个几何图形赋予属性值

                 //找到json中的attributes部分
                 var attributes = objJsonFeatures[i]["attributes"];
                 foreach (var attribute in attributes)
                 {
                     string name = GetSubString(attribute.Name, );
                     string value = attribute.Value.ToString();
                     int typeFieldIndex = featureClass.FindField(name);
                     featureBuffer.set_Value(typeFieldIndex, value);
                 }
                 // Set the feature buffer's shape and insert it.
                 featureBuffer.Shape = geometry;
                 featureCursor.InsertFeature(featureBuffer);
                 i++;
             }

             // Flush the buffer to the geodatabase.
             featureCursor.Flush();

         }

综合以上程序，就能将图形输出到指定目录，并自定义文件名

以此随笔，纪念我逝去的两星期时间 T-T