关于IFeatureClass和IFeatureLayer中的Search的区别

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.
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using ESRI.ArcGIS.Carto; using ESRI.ArcGIS.Geodatabase; namespace WindowsFormsApplication1 { public partial class Form2 : Form { private Form1 mainForm; // 主窗体引用 private ILayer selectedLayer; // 当前选中的图层 public Form2(Form1 form) { InitializeComponent(); mainForm = form; } private void Form2_Load(object sender, EventArgs e) { // 初始化图层列表 LoadLayers(); } // 加载图层到下拉列表 private void LoadLayers() { cboLayers.Items.Clear(); IMap map = mainForm.axMapControl1.Map; for (int i = 0; i < map.LayerCount; i++) { ILayer layer = map.get_Layer(i); cboLayers.Items.Add(layer.Name); } if (cboLayers.Items.Count > 0) { cboLayers.SelectedIndex = 0; } } // 获取当前选中的图层 private ILayer GetSelectedLayer() { if (cboLayers.SelectedIndex < 0) return null; string layerName = cboLayers.SelectedItem.ToString(); IMap map = mainForm.axMapControl1.Map; for (int i = 0; i < map.LayerCount; i++) { if (map.get_Layer(i).Name == layerName) { return map.get_Layer(i); } } return null; } // 图层选择改变时加载字段 private void cboLayers_SelectedIndexChanged(object sender, EventArgs e) { LoadFields(); } // 加载字段到字段下拉框 private void LoadFields() { cboFields.Items.Clear(); selectedLayer = GetSelectedLayer(); if (selectedLayer == null) return; IFeatureLayer featureLayer = selectedLayer as IFeatureLayer; if (featureLayer == null) return; IFeatureClass featureClass = featureLayer.FeatureClass; IFields fields = featureClass.Fields; for (int i = 0; i < fields.FieldCount; i++) { IField field = fields.get_Field(i); cboFields.Items.Add(field.Name); } if (cboFields.Items.Count > 0) { cboFields.SelectedIndex = 0; } } // 获取唯一值 private void btnGetUniqueValues_Click(object sender, EventArgs e) { selectedLayer = GetSelectedLayer(); if (selectedLayer == null) return; IFeatureLayer featureLayer = selectedLayer as IFeatureLayer; if (featureLayer == null) { MessageBox.Show("请选择一个要素图层"); return; } IFeatureClass featureClass = featureLayer.FeatureClass; if (cboFields.SelectedIndex < 0) { MessageBox.Show("请选择字段"); return; } string fieldName = cboFields.SelectedItem.ToString(); int fieldIndex = featureClass.FindField(fieldName); if (fieldIndex == -1) { MessageBox.Show($"字段 '{fieldName}' 不存在"); return; } // 获取唯一值 IDataStatistics dataStats = new DataStatisticsClass(); dataStats.Field = fieldName; ICursor cursor = featureClass.Search(null, true); dataStats.Cursor = cursor; IEnumerator enumerator = dataStats.UniqueValues; lstValues.Items.Clear(); while (enumerator.MoveNext()) { lstValues.Items.Add(enumerator.Current.ToString()); } } // 添加到查询条件 private void btnAddToQuery_Click(object sender, EventArgs e) { if (lstValues.SelectedItem != null) { string value = lstValues.SelectedItem.ToString(); string field = cboFields.SelectedItem.ToString(); if (!string.IsNullOrEmpty(field) && !string.IsNullOrEmpty(value)) { if (txtWhereClause.Text.Length > 0) { txtWhereClause.Text += " "; } txtWhereClause.Text += $"{field} = '{value}'"; } } } // 双击列表项添加到查询条件 private void lstValues_DoubleClick(object sender, EventArgs e) { if (lstValues.SelectedItem != null) { string value = lstValues.SelectedItem.ToString(); string field = cboFields.SelectedItem.ToString(); if (!string.IsNullOrEmpty(field) && !string.IsNullOrEmpty(value)) { if (txtWhereClause.Text.Length > 0) { txtWhereClause.Text += " "; } txtWhereClause.Text += $"{field} = '{value}'"; } } } // 验证查询条件 private void btnValidate_Click(object sender, EventArgs e) { selectedLayer = GetSelectedLayer(); if (selectedLayer == null) return; IFeatureLayer featureLayer = selectedLayer as IFeatureLayer; if (featureLayer == null) { MessageBox.Show("请选择一个要素图层"); return; } string whereClause = txtWhereClause.Text.Trim(); if (string.IsNullOrEmpty(whereClause)) { MessageBox.Show("查询条件不能为空"); return; } try { IQueryFilter queryFilter = new QueryFilterClass(); queryFilter.WhereClause = whereClause; // 尝试获取一个要素来验证查询 IFeatureCursor cursor = featureLayer.FeatureClass.Search(queryFilter, false); IFeature feature = cursor.NextFeature(); if (feature != null) { MessageBox.Show("查询条件有效"); } else { MessageBox.Show("查询条件有效,但没有匹配的记录"); } } catch (Exception ex) { MessageBox.Show($"查询条件无效: {ex.Message}"); } } // 应用查询 private void btnApply_Click(object sender, EventArgs e) { selectedLayer = GetSelectedLayer(); if (selectedLayer == null) return; IFeatureLayer featureLayer = selectedLayer as IFeatureLayer; if (featureLayer == null) { MessageBox.Show("请选择一个要素图层"); return; } string whereClause = txtWhereClause.Text.Trim(); if (string.IsNullOrEmpty(whereClause)) { MessageBox.Show("查询条件不能为空"); return; } try { IQueryFilter queryFilter = new QueryFilterClass(); queryFilter.WhereClause = whereClause; // 执行查询 IFeatureCursor cursor = featureLayer.FeatureClass.Search(queryFilter, false); IFeature feature; List<int> oidList = new List<int>(); // 获取所有符合条件的OID while ((feature = cursor.NextFeature()) != null) { oidList.Add(feature.OID); } // 在Form1中高亮显示 mainForm.HighlightFeatures(selectedLayer, oidList); // 加载属性数据 LoadAttributeData(featureLayer, queryFilter); MessageBox.Show($"找到 {oidList.Count} 条记录"); } catch (Exception ex) { MessageBox.Show($"查询失败: {ex.Message}"); } } // 加载属性数据到DataGridView private void LoadAttributeData(IFeatureLayer featureLayer, IQueryFilter queryFilter) { ITable table = featureLayer.FeatureClass as ITable; if (table == null) return; DataTable dataTable = new DataTable(); IFields fields = table.Fields; // 添加列 for (int i = 0; i < fields.FieldCount; i++) { IField field = fields.get_Field(i); dataTable.Columns.Add(field.AliasName, typeof(string)); } // 查询数据 ICursor cursor = table.Search(queryFilter, false); IRow row; int maxRecords = 1000; // 限制记录数 int recordCount = 0; while ((row = cursor.NextRow()) != null && recordCount < maxRecords) { DataRow dataRow = dataTable.NewRow(); for (int i = 0; i < fields.FieldCount; i++) { object value = row.get_Value(i); dataRow[i] = value == null ? string.Empty : value.ToString(); } dataTable.Rows.Add(dataRow); recordCount++; } dgvResults.DataSource = dataTable; } // 关闭窗体 private void btnClose_Click(object sender, EventArgs e) { this.Close(); } // 清除查询条件 private void btnClear_Click(object sender, EventArgs e) { txtWhereClause.Text = ""; } // 逻辑运算符按钮点击事件 private void OperatorButton_Click(object sender, EventArgs e) { Button btn = sender as Button; if (btn != null) { if (txtWhereClause.Text.Length > 0) { txtWhereClause.Text += " "; } txtWhereClause.Text += btn.Text + " "; } } // 括号按钮点击事件 private void btnParentheses_Click(object sender, EventArgs e) { Button btn = sender as Button; if (btn != null) { if (txtWhereClause.Text.Length > 0) { txtWhereClause.Text += " "; } txtWhereClause.Text += btn.Text; } } } }不改变代码内容,仅将美元符号的字符串插值,全部替换为format方法,因为我是vs2010版本不支持美元字符串插值
最新发布
07-14
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