Map 3D可以通过FDO技术连接到各种数据源，包括SHP文件，SDF文件，MySQL，SQL Server Spatial，Oracle等等。当然了，连接到不同数据源肯定有不同的参数，或者理解成连接字符串的组成部分。那这些参数都是什么呢？我们可以通过下面一段代码来深入理解这个参数：

闲话不多少，直接上代码，你可以在Map 3D中运行一下就会发觉他的奥妙：

using Autodesk.AutoCAD;using Autodesk.AutoCAD.Runtime;using OSGeo.FDO;using OSGeo.FDO.Commands;using OSGeo.FDO.Commands.Schema;using OSGeo.FDO.Connections;using Autodesk.AutoCAD.EditorInput;using Autodesk.AutoCAD.ApplicationServices;using OSGeo.FDO.Schema;using OSGeo.FDO.Connections.Capabilities;using OSGeo.FDO.ClientServices;using OSGeo.FDO.Commands.DataStore;    public class Class1    {        IConnection m_pConnection = null;        Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;        FeatureClass m_baseClass;        FeatureClass m_riverClass;        ProviderCollection m_Providers;        string m_sProviderName;        [CommandMethod("connect")]        public void Connect()        {            IConnectionManager connMgr;            int index;            Provider provider;            IProviderRegistry registry = FeatureAccessManager.GetProviderRegistry();            m_Providers = registry.GetProviders();            for (int i = 0; i < m_Providers.Count; i++)            {                provider = m_Providers[i];                ed.WriteMessage(string.Format("FDO support provider {0}, its index is {1} \n", provider.Name, i));            }            PromptIntegerResult intRes = ed.GetInteger("please input the provider's index");            if (intRes.Status == PromptStatus.OK)            {                index = intRes.Value;               provider = m_Providers[index];                m_sProviderName = provider.Name;                string shortName = provider.Name.Split('.')[1];                try                {                    connMgr = FeatureAccessManager.GetConnectionManager();                    m_pConnection = connMgr.CreateConnection(m_sProviderName);                    IConnectionInfo connInfo = m_pConnection.ConnectionInfo;                    IConnectionPropertyDictionary properties = connInfo.ConnectionProperties;                    InputParametersValue(properties);                    ConnectionState connState = m_pConnection.Open();                                        ed.WriteMessage("connect status is "+connState.ToString() + "\n");                }                catch (OSGeo.FDO.Common.Exception exception)                {                    ed.WriteMessage("There are some exceptions with message : " + exception.Message + "\n");                }                            }            else            {                ed.WriteMessage("you did not select a correct provider , exit \n");                return;            }        }        [CommandMethod("DisConnect")]        public void CloseConnection()        {            m_pConnection.Close();        }        private void InputParametersValue(IConnectionPropertyDictionary properties)        {            string[] propertiesNames = properties.PropertyNames;            foreach (string name in propertiesNames)            {                PromptStringOptions pso = new PromptStringOptions("Please input the value for \"" + name + "\":");                PromptResult psr = ed.GetString(pso);                if (properties.IsPropertyRequired(name))                {                    while (psr.Status != PromptStatus.OK)                    {                        ed.WriteMessage(string.Format("Parameter \"{0}\" is required, please input value again\n", name));                        psr = ed.GetString(pso);                    }                    properties.SetProperty(name, psr.StringResult);                }            }        }        private void ListPropertiesParameters(IDataStorePropertyDictionary properties)        {            foreach (string name in properties.PropertyNames)            {                ed.WriteMessage(name + "\n");            }        }        [CommandMethod("CreateDataStore")]        public void CreateDataStore()        {            ICreateDataStore createDS = m_pConnection.CreateCommand(CommandType.CommandType_CreateDataStore) as ICreateDataStore;            IDataStorePropertyDictionary properties = createDS.DataStoreProperties;            InputParametersValue(properties);            createDS.Execute();        }}