C#开发读取Geodatabase10的XML值

ArcGIS10已经推出快一年的时间了，在去年的用户大会上关于Geodatabase10的新特性上描述我们的相关Schema也发生了本质的变化，从原来的30多张表，变成现在的6张，那么最本质的变化就是相关的对象使用XML进行存储，这对我们开发者来说是一个好消息，因为我们可以通过XML结构来得知每一个对象是怎么定义的，而且我们也可以使用SQL来读取XML的值而不用使用ArcObject来读取。
关于Geodatabase10新特性可以参考：http://wenku.baidu.com/view/94721478168884868762d668.html
那么今天就给大家介绍一下怎么使用C#来访问这些值，其实抛开ArcGIS的知识，一个纯IT的开发人员只要了解XML的都会很容易的来获得这些信息。
首先看一下一个要素类为DLTB的XML格式

<DEFeatureClassInfo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:typens="http://www.esri.com/schemas/ArcGIS/10.0" xsi:type="typens:DEFeatureClassInfo">
  <CatalogPath>/sde.SDE.czdj/sde.SDE.dltb</CatalogPath>
  <Name>sde.SDE.dltb</Name>
  <ChildrenExpanded>false</ChildrenExpanded>
  <DatasetType>esriDTFeatureClass</DatasetType>
  <DSID>8</DSID>
  <Versioned>false</Versioned>
  <CanVersion>false</CanVersion>
  <ConfigurationKeyword />
  <HasOID>true</HasOID>
  <OIDFieldName>OBJECTID</OIDFieldName>
  <GPFieldInfoExs xsi:type="typens:ArrayOfGPFieldInfoEx">
    <GPFieldInfoEx xsi:type="typens:GPFieldInfoEx">
      <Name>OBJECTID</Name>
      <ModelName>OBJECTID</ModelName>
      <FieldType>esriFieldTypeOID</FieldType>
      <IsNullable>false</IsNullable>
      <Required>true</Required>
      <Editable>false</Editable>
    </GPFieldInfoEx>
    <GPFieldInfoEx xsi:type="typens:GPFieldInfoEx">
      <Name>Shape</Name>
      <ModelName>Shape</ModelName>
      <FieldType>esriFieldTypeGeometry</FieldType>
      <IsNullable>true</IsNullable>
      <Required>true</Required>
    </GPFieldInfoEx>
    <GPFieldInfoEx xsi:type="typens:GPFieldInfoEx">
      <Name>Shape.area</Name>
      <ModelName>Shape.area</ModelName>
      <FieldType>esriFieldTypeDouble</FieldType>
      <IsNullable>false</IsNullable>
      <Required>true</Required>
      <Editable>false</Editable>
    </GPFieldInfoEx>
    <GPFieldInfoEx xsi:type="typens:GPFieldInfoEx">
      <Name>Shape.len</Name>
      <ModelName>Shape.len</ModelName>
      <FieldType>esriFieldTypeDouble</FieldType>
      <IsNullable>false</IsNullable>
      <Required>true</Required>
      <Editable>false</Editable>
    </GPFieldInfoEx>
  </GPFieldInfoExs>
  <CLSID>{52353152-891A-11D0-BEC6-00805F7C4268}</CLSID>
  <EXTCLSID />
  <RelationshipClassNames xsi:type="typens:Names" />
  <AliasName />
  <ModelName />
  <HasGlobalID>false</HasGlobalID>
  <GlobalIDFieldName />
  <RasterFieldName />
  <ExtensionProperties xsi:type="typens:PropertySet">
    <PropertyArray xsi:type="typens:ArrayOfPropertySetProperty" />
  </ExtensionProperties>
  <ControllerMemberships xsi:type="typens:ArrayOfControllerMembership">
    <ControllerMembership xsi:type="typens:TopologyMembership">
      <TopologyName>sde.SDE.czdj_Topology</TopologyName>
      <Weight>5</Weight>
      <XYRank>1</XYRank>
      <ZRank>1</ZRank>
      <EventNotificationOnValidate>false</EventNotificationOnValidate>
    </ControllerMembership>
  </ControllerMemberships>
  <FeatureType>esriFTSimple</FeatureType>
  <ShapeType>esriGeometryPolygon</ShapeType>
  <ShapeFieldName>Shape</ShapeFieldName>
  <HasM>false</HasM>
  <HasZ>false</HasZ>
  <HasSpatialIndex>true</HasSpatialIndex>
  <AreaFieldName>Shape.area</AreaFieldName>
  <LengthFieldName>Shape.len</LengthFieldName>
  <Extent xsi:type="typens:EnvelopeN">
    <XMin>506464.78390000015</XMin>
    <YMin>3842861.5803999994</YMin>
    <XMax>516750</XMax>
    <YMax>3849454.2771000005</YMax>
    <SpatialReference xsi:type="typens:ProjectedCoordinateSystem">
      <WKT>PROJCS["Xian_1980_3_Degree_GK_CM_111E",GEOGCS["GCS_Xian_1980",DATUM["D_Xian_1980",SPHEROID["Xian_1980",6378140.0,298.257]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Gauss_Kruger"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",111.45],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]</WKT>
      <XOrigin>-5123200</XOrigin>
      <YOrigin>-10002100</YOrigin>
      <XYScale>10000</XYScale>
      <ZOrigin>0</ZOrigin>
      <ZScale>1</ZScale>
      <MOrigin>0</MOrigin>
      <MScale>1</MScale>
      <XYTolerance>0.001</XYTolerance>
      <ZTolerance>0.001</ZTolerance>
      <MTolerance>0.001</MTolerance>
      <HighPrecision>true</HighPrecision>
    </SpatialReference>
  </Extent>
  <SpatialReference xsi:type="typens:ProjectedCoordinateSystem">
    <WKT>PROJCS["Xian_1980_3_Degree_GK_CM_111E",GEOGCS["GCS_Xian_1980",DATUM["D_Xian_1980",SPHEROID["Xian_1980",6378140.0,298.257]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Gauss_Kruger"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",111.45],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]</WKT>
    <XOrigin>-5123200</XOrigin>
    <YOrigin>-10002100</YOrigin>
    <XYScale>10000</XYScale>
    <ZOrigin>-100000</ZOrigin>
    <ZScale>10000</ZScale>
    <MOrigin>-100000</MOrigin>
    <MScale>10000</MScale>
    <XYTolerance>0.001</XYTolerance>
    <ZTolerance>0.001</ZTolerance>
    <MTolerance>0.001</MTolerance>
    <HighPrecision>true</HighPrecision>
  </SpatialReference>
</DEFeatureClassInfo>

我们可以看到，这个XML定义了要素类的名称、字段（字段的相关属性）、投影信息、范围等信息
------------------------Oracle----------------------------------------------------------------
在Oracle数据库中的存储并不是直接存储在Defination里面



而且需要使用sde.sdexmltotext操作符来转换一下
参考示例代码

using System.Xml.Linq;
using System.Xml;
using System.Xml.XPath;   
using (OracleConnection connection = new OracleConnection())
            {
                connection.ConnectionString = "User Id=sde;Password=sde;Data Source=orcl;";
                connection.Open();
                OracleCommand cmd = new OracleCommand();
                string sql = "SELECT sde.sdexmltotext(d1.xml_doc) as definition " +
                "FROM GDB_ITEMS LEFT OUTER JOIN SDE_XML_DOC1 d1 ON " +
                "GDB_ITEMS.definition = d1.sde_xml_id where name='TEST.dltb'";
                cmd.CommandText = sql;
                cmd.Connection = connection;
                using (OracleDataReader dr = cmd.ExecuteReader())
                {
                    while (dr.Read())
                    {
                        string def = System.Convert.ToString(dr.GetValue(0));
                        XDocument xd = XDocument.Parse(def);
                        StringBuilder str = new StringBuilder();
                        int i = 1;
                        foreach (XElement ele in xd.Descendants("GPFieldInfoEx"))
                        {
                            string name = ele.Element("Name").Value;
                            string code = ele.Element("FieldType").Value;
                            str.Append(i+"："+name + "," + code+"/n");
                            i++;
                        }
                        LSCommonHelper.MessageBoxHelper.ShowMessageBox(str.ToString());
                       
                    }
               
                }

----------------------------------------------SQL Server----------------------------------
在SQL Server中，完全使用SQL语句直接对XML进行获得值，而不需要引用C#的类库

select
definition.value('(/DEFeatureClassInfo/Name)[1]','nvarchar(max)') as "要素类名称",
definition.value('(/DEFeatureClassInfo/DatasetType)[1]','nvarchar(max)') as "要素类类型",
definition.value('(/DEFeatureClassInfo/GPFieldInfoExs/GPFieldInfoEx/Name)[1]','nvarchar(max)') as "字段1",
definition.value('(/DEFeatureClassInfo/GPFieldInfoExs/GPFieldInfoEx/Name)[2]','nvarchar(max)') as "字段2",
definition.value('(/DEFeatureClassInfo/GPFieldInfoExs/GPFieldInfoEx/Name)[3]','nvarchar(max)') as "字段3"
FROM [sde].[sde].[GDB_ITEMS]
WHERE Name='test.DBO.zd'

----------------------------------------------Oracle----------------------------------

SELECT
  EXTRACTVALUE(XMLType(Definition), '/DEWorkspace/MajorVersion') AS "Major version",
  EXTRACTVALUE(XMLType(Definition), '/DEWorkspace/MinorVersion') AS "Minor version",
  EXTRACTVALUE(XMLType(Definition), '/DEWorkspace/BugfixVersion') AS "Bug fix version"
FROM
 sde.gdb_items_vw items INNER JOIN
  (SELECT UUID 
   FROM sde.gdb_itemtypes
   WHERE Name = 'Workspace') itemtypes
  ON items.Type = itemtypes.UUID;

---------------------------------------File Geodatabase---------------------------------
如果用户使用FGDB，那么可以使用FileGDB API来获得相关的信息