ArcGIS的UID

 

關于什么是GUID，ProgID ，CLSID和UID，在ESRI的Document Library能夠找到下面的描述.

COM interfaces and coclasses are identified by a globally unique identifier (GUID). The GUID for an interface is called an interface ID (IID). The GUID for a coclass is called class ID (CLSID). A ProgID is a text alias for a CLSID; the ProgID is a string composed of the project name and the class name of the coclass.

The UID coclass can be used to represent the GUID of an object.

There is built-in module called ArcID in the VBA project for the Normal template in both ArcMap and ArcCatalog. This module is a utility for finding the UID of the built-in commands and toolbars. You pass the name of a command or toolbar in as an argument to ArcID and the UID of that item is returned. The ArcID module is regenerated every time the Normal template is loaded; the registry is read to get the GUIDs of all the commands and toolbars that are currently used by the application.

簡單的說，GUID(全局统一标识符)是用來標識識別COM接口和組件，保证它們的唯一性，避免出現版本不一致而導致的組件沖突.IID就是接口的GUID表示，CLSID則是組件類的GUID表示。ProgID是程序员给某个CLSID指定一个易记的名字.UID則是物象（Object)的GUID. 以下是一些ILayer接口的UID,通過使用它們，我們可以快速找到所需的圖層。 這些ESRI接口存放在注冊表中的 HKEY_CLASSES_ROOT下面，如果想查詢它們的UID，可以通過查找它們的名字，從而找到對應的UID.

{6CA416B1-E160-11D2-9F4E-00C04F6BC78E} IDataLayer
{40A9E885-5533-11d0-98BE-00805F7CED21} IFeatureLayer
{E156D7E5-22AF-11D3-9F99-00C04F6BC78E} IGeoFeatureLayer
{34B2EF81-F4AC-11D1-A245-080009B6F22B} IGraphicsLayer
{5CEAE408-4C0A-437F-9DB3-054D83919850} IFDOGraphicsLayer
{0C22A4C7-DAFD-11D2-9F46-00C04F6BC78E} ICoverageAnnotationLayer
{EDAD6644-1810-11D1-86AE-0000F8751720} IGroupLayer
{D02371C7-35F7-11D2-B1F2-00C04F8EDEFF} IRasterLayer

 下面是一個查找groupLayer的例子

Public Function FindGroupLayer()Function FindGroupLayer(ByVal sGroupName_IN As String, ByRef pmap_IN As IMap) As ILayer
    On Error GoTo errhandle

    Dim Result As ILayer
    Set Result = Nothing
    Dim pL As IGroupLayer
    Dim pel As IEnumLayer
    Dim uid As New uid

    uid.Value = "{EDAD6644-1810-11D1-86AE-0000F8751720}"

    Set pel = pmap_IN.Layers(uid, True)

    Set pL = pel.Next
    Dim sGroupName As String
    sGroupName = UCase(sGroupName_IN)
    
    While Not pL Is Nothing
        
        If UCase(pL.Name) = sGroupName Then
            Set FindGroupLayer = pL
            Exit Function
        End If
        
        Set pL = pel.Next
    Wend
    Set FindGroupLayer = Result
    
    Exit Function

errhandle:
    'MsgBox "FindgroupLayer Error: " & Err.Description
    Set FindGroupLayer = Nothing
End Function