C# で `StreamReader` を使用して Excel ファイルを読み取る方法

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        // This code will NOT work - demonstrates the problem
        try
        {
            using (StreamReader reader = new StreamReader("ProductData.xlsx"))
            {
                string content = reader.ReadLine(); // read data
                Console.WriteLine(content); // Outputs garbled binary data
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

Imports System
Imports System.IO

Module Program
    Sub Main(args As String())
        ' This code will NOT work - demonstrates the problem
        Try
            Using reader As New StreamReader("ProductData.xlsx")
                Dim content As String = reader.ReadLine() ' read data
                Console.WriteLine(content) ' Outputs garbled binary data
            End Using
        Catch ex As Exception
            Console.WriteLine($"Error: {ex.Message}")
        End Try
    End Sub
End Module

using IronXL;
using System.IO;
using System.Data;
using System.Threading.Tasks;

public class StreamProcessor
{
    // Async method for container health checks
    public async Task<bool> ProcessExcelStreamAsync(byte[] fileBytes)
    {
        try
        {
            using (MemoryStream stream = new MemoryStream(fileBytes))
            {
                // Load from stream asynchronously
                WorkBook workbook = WorkBook.FromStream(stream);
                WorkSheet worksheet = workbook.DefaultWorkSheet;

                // Process the data
                int rowCount = worksheet.RowCount;
                Console.WriteLine($"The worksheet has {rowCount} rows");

                // Read all data into a DataTable for database operations
                var dataTable = worksheet.ToDataTable(true); // true = use first row as headers

                // Validate data integrity
                if (dataTable.Rows.Count == 0)
                {
                    Console.WriteLine("Warning: No data rows found");
                    return false;
                }

                Console.WriteLine($"Loaded {dataTable.Rows.Count} data rows");
                Console.WriteLine($"Columns: {string.Join(", ", dataTable.Columns.Cast<DataColumn>().Select(c => c.ColumnName))}");

                // Example: Process data for container metrics
                foreach (DataRow row in dataTable.Rows)
                {
                    // Your processing logic here
                    await ProcessRowAsync(row);
                }

                return true;
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Stream processing error: {ex.Message}");
            return false;
        }
    }

    private async Task ProcessRowAsync(DataRow row)
    {
        // Simulate async processing
        await Task.Delay(10);
    }
}

Imports IronXL
Imports System.IO
Imports System.Data
Imports System.Threading.Tasks

Public Class StreamProcessor
    ' Async method for container health checks
    Public Async Function ProcessExcelStreamAsync(fileBytes As Byte()) As Task(Of Boolean)
        Try
            Using stream As New MemoryStream(fileBytes)
                ' Load from stream asynchronously
                Dim workbook As WorkBook = WorkBook.FromStream(stream)
                Dim worksheet As WorkSheet = workbook.DefaultWorkSheet

                ' Process the data
                Dim rowCount As Integer = worksheet.RowCount
                Console.WriteLine($"The worksheet has {rowCount} rows")

                ' Read all data into a DataTable for database operations
                Dim dataTable = worksheet.ToDataTable(True) ' True = use first row as headers

                ' Validate data integrity
                If dataTable.Rows.Count = 0 Then
                    Console.WriteLine("Warning: No data rows found")
                    Return False
                End If

                Console.WriteLine($"Loaded {dataTable.Rows.Count} data rows")
                Console.WriteLine($"Columns: {String.Join(", ", dataTable.Columns.Cast(Of DataColumn)().Select(Function(c) c.ColumnName))}")

                ' Example: Process data for container metrics
                For Each row As DataRow In dataTable.Rows
                    ' Your processing logic here
                    Await ProcessRowAsync(row)
                Next

                Return True
            End Using
        Catch ex As Exception
            Console.WriteLine($"Stream processing error: {ex.Message}")
            Return False
        End Try
    End Function

    Private Async Function ProcessRowAsync(row As DataRow) As Task
        ' Simulate async processing
        Await Task.Delay(10)
    End Function
End Class

using IronXL;
using System;
using System.IO;

public class FormatConverter
{
    public static void ConvertExcelFormats()
    {
        try
        {
            // Load an Excel file and save as CSV with options
            WorkBook workbook = WorkBook.Load("data.xlsx");

            // Save with UTF-8 encoding for international character support
            workbook.SaveAsCsv("output.csv", ";"); // Use semicolon as delimiter

            // Load a CSV file with custom settings
            WorkBook csvWorkbook = WorkBook.LoadCSV("input.csv", ",", "UTF-8");
            csvWorkbook.SaveAs("output.xlsx", FileFormat.XLSX);

            // Export specific worksheet to CSV
            if (workbook.WorkSheets.Count > 0)
            {
                WorkSheet worksheet = workbook.WorkSheets[0];
                worksheet.SaveAsCsv("worksheet1.csv");

                // Advanced: Export only specific range
                var dataRange = worksheet["A1:D100"];
                // Process range data before export
                foreach (var cell in dataRange)
                {
                    if (cell.IsNumeric)
                    {
                        // Apply formatting for CSV output
                        cell.FormatString = "0.00";
                    }
                }
            }

            Console.WriteLine("Conversion completed successfully");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Conversion error: {ex.Message}");
            throw; // Re-throw for container orchestrator handling
        }
    }
}

Imports IronXL
Imports System
Imports System.IO

Public Class FormatConverter
    Public Shared Sub ConvertExcelFormats()
        Try
            ' Load an Excel file and save as CSV with options
            Dim workbook As WorkBook = WorkBook.Load("data.xlsx")

            ' Save with UTF-8 encoding for international character support
            workbook.SaveAsCsv("output.csv", ";") ' Use semicolon as delimiter

            ' Load a CSV file with custom settings
            Dim csvWorkbook As WorkBook = WorkBook.LoadCSV("input.csv", ",", "UTF-8")
            csvWorkbook.SaveAs("output.xlsx", FileFormat.XLSX)

            ' Export specific worksheet to CSV
            If workbook.WorkSheets.Count > 0 Then
                Dim worksheet As WorkSheet = workbook.WorkSheets(0)
                worksheet.SaveAsCsv("worksheet1.csv")

                ' Advanced: Export only specific range
                Dim dataRange = worksheet("A1:D100")
                ' Process range data before export
                For Each cell In dataRange
                    If cell.IsNumeric Then
                        ' Apply formatting for CSV output
                        cell.FormatString = "0.00"
                    End If
                Next
            End If

            Console.WriteLine("Conversion completed successfully")
        Catch ex As Exception
            Console.WriteLine($"Conversion error: {ex.Message}")
            Throw ' Re-throw for container orchestrator handling
        End Try
    End Sub
End Class