关于IFeatureClass和IFeatureLayer中的Search的区别

最新推荐文章于 2021-08-05 18:39:24 发布

转载最新推荐文章于 2021-08-05 18:39:24 发布 · 7.1k 阅读

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#search #string #测试

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本文探讨了在遍历图层要素时如何正确选择IFeatureClass与IFeatureLayer中的Search方法，以确保显示已更新的图层数据。通过具体代码示例展示了如何使用IFeatureLayer的Search方法来实现这一目标。

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近来做关于打开图层属性表时有个小发现，就是在遍历图层中的要素时要用的Search方法，但是IFeatureClass和IFeatureLayer中都有这个方法，到底用哪个呢？测试了下，如果用IFeatureClass中的Search方法，那么打开的是原始图层中所有元素的属性，那么即使我对一个图层进行了编辑，比如删除了这个图层中的某些要素，但是打开属性表时里面的数据内容还是原始图层的内容。因此，要想对更新后的图层进行属性表的浏览，就要用到IFeatureLayer.Search方法了。
现在贴出打开属性表的代码，以便更直观的展示给大家。
  Public Sub LoadDatatoView(ByVal pFeatureLayer As ILayer, ByVal dtGridView As DataGridView)
      Dim aa As IFeatureLayer = CType(pFeatureLayer, IFeatureLayer)
      Dim pFields As IFields = aa.FeatureClass.Fields
      Dim pDataTable As New DataTable
      Dim i As Int32
      For i = 0 To pFields.FieldCount - 1
         Dim fldName As String
         fldName = pFields.Field(i).AliasName
         pDataTable.Columns.Add(fldName)
      Next
      Dim pFeatureCursor As IFeatureCursor
      Dim pQueryFilter As IQueryFilter '查询过滤器
      pQueryFilter = New QueryFilter '创建一个新的查询过滤器
      pQueryFilter.WhereClause = ""
   pFeatureCursor = aa.Search(pQueryFilter, False)
      Dim pFeature As IFeature
      pFeature = pFeatureCursor.NextFeature()
      While (Not pFeature Is Nothing)
         Dim j As Int32
         Dim fldValue As String
         Dim dr As DataRow = pDataTable.NewRow()
         For j = 0 To pFields.FieldCount - 1
            Dim fldName As String
            fldName = pFields.Field(j).AliasName

            If fldName = "Shape" Then
                  If pFeature.Shape.GeometryType = 1 Then
                     fldValue = "point"
                  ElseIf pFeature.Shape.GeometryType = 3 Then
                     fldValue = "polyline"
                  ElseIf pFeature.Shape.GeometryType = 4 Then
                     fldValue = "polygon"
                  Else
                     fldValue = "unknown type"
                  End If

            Else
                  fldValue = pFeature.Value(j).ToString()
            End If
            dr(j) = fldValue
         Next
         pDataTable.Rows.Add(dr)
         pFeature = pFeatureCursor.NextFeature()
      End While
      dtGridView.DataSource = pDataTable
End Sub
其中的pfeatureCursor = aa.Search(pQueryFilter, False),这句话aa是IFeatureLayer,而不是IFeatureClass.