datagridview-import-excel ソースコード全文

<Solution>
  <Project Path="DataGridView_Import_Excel/DataGridView_Import_Excel.csproj" />
</Solution>

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net10.0-windows</TargetFramework>
    <Nullable>enable</Nullable>
    <UseWindowsForms>true</UseWindowsForms>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

  <ItemGroup>
    <COMReference Include="Microsoft.Office.Interop.Excel">
      <WrapperTool>tlbimp</WrapperTool>
      <VersionMinor>9</VersionMinor>
      <VersionMajor>1</VersionMajor>
      <Guid>00020813-0000-0000-c000-000000000046</Guid>
      <Lcid>0</Lcid>
      <Isolated>false</Isolated>
      <EmbedInteropTypes>true</EmbedInteropTypes>
    </COMReference>
  </ItemGroup>

  <ItemGroup>
    <None Update="商品リスト.xlsx">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>

</Project>

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="Current" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
    <ItemGroup>
        <Compile Update="Form1.cs">
            <SubType>Form</SubType>
        </Compile>
    </ItemGroup>
</Project>

using System.Data;
using System.Runtime.InteropServices;
// 長い名前空間を省略するため、ファイルの最上部で別名を定義します
using Excel = Microsoft.Office.Interop.Excel;

namespace DataGridView_Import_Excel;

public partial class Form1 : Form
{
    private DataTable _dataTable = new DataTable();

    public Form1()
    {
        InitializeComponent();
        InitializeDataGridView();

        // ボタンのクリックイベントを購読
        btnImportExcel.Click += btnImportExcel_Click;
    }

    private void InitializeDataGridView()
    {
        // エクスポート時と同じデータ構造（3列）で DataTable を定義
        _dataTable.Columns.Add("Code", typeof(string));
        _dataTable.Columns.Add("Name", typeof(string));
        _dataTable.Columns.Add("Price", typeof(int));

        dataGridView1.DataSource = _dataTable;
        dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
    }

    /// <summary>
    /// 「Excel読込」ボタンのクリックイベント
    /// </summary>
    private void btnImportExcel_Click(object? sender, EventArgs e)
    {
        // 読込元のファイルをユーザーに選択させる（OpenFileDialog）
        using var ofd = new OpenFileDialog();
        ofd.Filter = "Excel ブック (*.xlsx)|*.xlsx|従来の Excel ブック (*.xls)|*.xls";
        if (ofd.ShowDialog() != DialogResult.OK) return;

        // 既存のグリッドデータを一度クリア
        _dataTable.Rows.Clear();

        // Excel関係のオブジェクトは try-finally で確実に解放するために外側で宣言します
        Excel.Application? excelApp = null;
        Excel.Workbooks? workbooks = null;
        Excel.Workbook? workbook = null;
        Excel.Sheets? sheets = null;
        Excel.Worksheet? worksheet = null;
        Excel.Range? usedRange = null;

        try
        {
            excelApp = new Excel.Application();
            workbooks = excelApp.Workbooks;
            workbook = workbooks.Open(ofd.FileName);
            sheets = workbook.Sheets;
            worksheet = (Excel.Worksheet)sheets[1]; // 1番目のシートを取得
            usedRange = worksheet.UsedRange;

            // セルを1つずつループで読むと遅いため、2次元配列として一括で読み込みます
            object[,] dataArray = (object[,])usedRange.Value2;

            int rowCount = dataArray.GetLength(0);
            int colCount = dataArray.GetLength(1);

            // 1行目はヘッダー（列名）のため、データ行である2行目からループを開始
            for (int r = 2; r <= rowCount; r++)
            {
                // 配列が Null の場合や列数が足りない場合を考慮した安全な値の取得
                string code = dataArray[r, 1]?.ToString() ?? "";
                string name = dataArray[r, 2]?.ToString() ?? "";

                // 数値型（Price）への安全なパース
                int price = 0;
                if (dataArray[r, 3] != null)
                {
                    int.TryParse(dataArray[r, 3].ToString(), out price);
                }

                // データの追加（空行をスキップしたい場合は、ここで適宜条件を挟みます）
                if (!string.IsNullOrEmpty(code) || !string.IsNullOrEmpty(name))
                {
                    _dataTable.Rows.Add(code, name, price);
                }
            }

            MessageBox.Show("Excel データを正常に読み込みました。", "インポート完了", MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
        catch (Exception ex)
        {
            MessageBox.Show($"エラーが発生しました:\n{ex.Message}", "エラー", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        finally
        {
            // 参照リーク（バックグラウンドに Excel が残る現象）を防止する解放処理
            if (workbook != null)
            {
                workbook.Close(false); // 上書き保存せずに閉じる
            }
            if (excelApp != null)
            {
                excelApp.Quit();
            }

            // COM オブジェクトを割り当てた逆順で確実に解放
            if (usedRange != null) Marshal.ReleaseComObject(usedRange);
            if (worksheet != null) Marshal.ReleaseComObject(worksheet);
            if (sheets != null) Marshal.ReleaseComObject(sheets);
            if (workbook != null) Marshal.ReleaseComObject(workbook);
            if (workbooks != null) Marshal.ReleaseComObject(workbooks);
            if (excelApp != null) Marshal.ReleaseComObject(excelApp);
        }
    }
}

namespace DataGridView_Import_Excel
{
    partial class Form1
    {
        /// <summary>
        ///  Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        ///  Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        ///  Required method for Designer support - do not modify
        ///  the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            tableLayoutPanel1 = new TableLayoutPanel();
            btnImportExcel = new Button();
            dataGridView1 = new DataGridView();
            tableLayoutPanel1.SuspendLayout();
            ((System.ComponentModel.ISupportInitialize)dataGridView1).BeginInit();
            SuspendLayout();
            //
            // tableLayoutPanel1
            //
            tableLayoutPanel1.ColumnCount = 1;
            tableLayoutPanel1.ColumnStyles.Add(new ColumnStyle(SizeType.Percent, 50F));
            tableLayoutPanel1.Controls.Add(btnImportExcel, 0, 1);
            tableLayoutPanel1.Controls.Add(dataGridView1, 0, 0);
            tableLayoutPanel1.Dock = DockStyle.Fill;
            tableLayoutPanel1.Location = new Point(0, 0);
            tableLayoutPanel1.Name = "tableLayoutPanel1";
            tableLayoutPanel1.RowCount = 2;
            tableLayoutPanel1.RowStyles.Add(new RowStyle(SizeType.Percent, 90.44444F));
            tableLayoutPanel1.RowStyles.Add(new RowStyle(SizeType.Percent, 9.555555F));
            tableLayoutPanel1.Size = new Size(800, 450);
            tableLayoutPanel1.TabIndex = 0;
            //
            // btnImportExcel
            //
            btnImportExcel.Dock = DockStyle.Fill;
            btnImportExcel.Location = new Point(3, 410);
            btnImportExcel.Name = "btnImportExcel";
            btnImportExcel.Size = new Size(794, 37);
            btnImportExcel.TabIndex = 0;
            btnImportExcel.Text = "エクセルデータをインポート";
            btnImportExcel.UseVisualStyleBackColor = true;
            //
            // dataGridView1
            //
            dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize;
            dataGridView1.Dock = DockStyle.Fill;
            dataGridView1.Location = new Point(3, 3);
            dataGridView1.Name = "dataGridView1";
            dataGridView1.RowHeadersWidth = 62;
            dataGridView1.Size = new Size(794, 401);
            dataGridView1.TabIndex = 1;
            //
            // Form1
            //
            AutoScaleDimensions = new SizeF(10F, 25F);
            AutoScaleMode = AutoScaleMode.Font;
            ClientSize = new Size(800, 450);
            Controls.Add(tableLayoutPanel1);
            Name = "Form1";
            Text = "Form1";
            tableLayoutPanel1.ResumeLayout(false);
            ((System.ComponentModel.ISupportInitialize)dataGridView1).EndInit();
            ResumeLayout(false);
        }

        #endregion

        private TableLayoutPanel tableLayoutPanel1;
        private Button btnImportExcel;
        private DataGridView dataGridView1;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<root>
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    Microsoft ResX Schema

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  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
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              <xsd:attribute ref="xml:space" />
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          </xsd:element>
          <xsd:element name="assembly">
            <xsd:complexType>
              <xsd:attribute name="alias" type="xsd:string" />
              <xsd:attribute name="name" type="xsd:string" />
            </xsd:complexType>
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          <xsd:element name="data">
            <xsd:complexType>
              <xsd:sequence>
                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
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namespace DataGridView_Import_Excel
{
    internal static class Program
    {
        /// <summary>
        ///  The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            // To customize application configuration such as set high DPI settings or default font,
            // see https://aka.ms/applicationconfiguration.
            ApplicationConfiguration.Initialize();
            Application.Run(new Form1());
        }
    }
}