读取.xlsx文件

首先，根据.xlsx文件的表头建立一个实体类

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public DateTime EnrollmentDate { get; set; }

}

建立一个Excel读取文件帮助类，

安装第三方包 NPOI

 public class ExcelReader
 {
     public static List<T> ReadExcelToList<T>(string filePath, bool hasHeader = true) where T : new()
     {
         List<T> resultList = new List<T>();
         var properties = typeof(T).GetProperties();

         using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
         {
             IWorkbook workbook = new XSSFWorkbook(fs);        //.xlsx文件
             ISheet sheet = workbook.GetSheetAt(0);        //第一个工作表

             //获取表头列索引与属性的映射
             Dictionary<int, string> columnMap = new Dictionary<int, string>();
             IRow headerRow = sheet.GetRow(0);            //假设表头在第一行

             if (hasHeader && headerRow != null)
             {
                 foreach (var cell in headerRow.Cells)
                 {
                     string columName = cell.StringCellValue.Trim();
                     var property = Array.Find(properties
                         , p => p.Name.Equals(columName, StringComparison.OrdinalIgnoreCase));

                     if (property != null)
                     {
                         columnMap[cell.ColumnIndex] = property.Name;
                     }
                 }
             }
             else
             {
                 //无表头，按列顺序映射属性
                 for (int i = 0; i < properties.Length; i++)
                 {
                     columnMap[i] = properties[i].Name;
                 }
             }


             //遍历数据行
             int startRow = hasHeader ? 1 : 0;
             for (int rowIndex = startRow; rowIndex <= sheet.LastRowNum; rowIndex++)
             {
                 IRow row = sheet.GetRow(rowIndex);
                 if (row == null)
                 {
                     continue;
                 }

                 T item = new T();
                 foreach (var pair in columnMap)
                 {
                     int colIndex = pair.Key;
                     string propName = pair.Value;
                     ICell cell = row.GetCell(colIndex);

                     var property = typeof(T).GetProperty(propName);

                     if (property != null && cell != null)
                     {
                         object value = GetCellValue(cell, property.PropertyType);

                         property.SetValue(item, value);
                         //SetValue方法的参数第一个是要设置属性的 对象实例（若属性是静态的，传 null），第二个是要赋给属性的 值
                     }
                 }
                 resultList.Add(item);
             }
         }
         return resultList;
     }

     /// <summary>
     /// 处理单元格数据类型
     /// </summary>
     /// <param name="cell"></param>
     /// <param name="propertyType"></param>
     /// <returns></returns>     
     private static object GetCellValue(ICell cell, Type targetType)
     {
         if (cell == null) return null;

         switch (cell.CellType)
         {
             case CellType.Numeric:
                 if (DateUtil.IsCellDateFormatted(cell))
                 {
                     return cell.DateCellValue;  //日期类型
                 }
                 else
                 {
                     double numValue = cell.NumericCellValue;
                     return Convert.ChangeType(numValue, targetType);  //数值类型
                 }

             case CellType.String:
                 var r=cell.StringCellValue.Trim();
                 return Convert.ChangeType(cell.StringCellValue.Trim(), targetType);

             case CellType.Boolean:
                 return cell.BooleanCellValue;

             default:
                 return null;
         }
     }
 }

在Main函数里测试一下

 static void Main(string[] args)
 {
		try
		{
         string filePath = "Students.xlsx";
         List<Student> students=ExcelReader.ReadExcelToList<Student>(filePath);
         foreach (var student in students)
         {
             Console.WriteLine($"ID: {student.Id}" +
                 $", 姓名: {student.Name}" +
                 $", 年龄: {student.Age}" +
                 $", 入学时间: {student.EnrollmentDate:yyyy-MM-dd}");
         }
	     }
		catch (FileNotFoundException)
		{
         Console.WriteLine("Excel 文件不存在！");
		}
     catch(Exception ex)
     {
         Console.WriteLine($"读取失败：{ex.Message}");
     }
 }

当然，也可以将读取到的数据存储到Dictionary中

public class StudentRepository
{
    private List<Student> _students=new List<Student>();
    private Dictionary<int, Student> _idIndex = new Dictionary<int, Student>();
    private Dictionary<string, Student> _nameIndex = new Dictionary<string, Student>();

    //初始化是构建索引
    public StudentRepository(List<Student> student)
    {
        _students = student;
        foreach (Student stu in _students)
        {
            _idIndex[stu.Id] = stu;
            _nameIndex[stu.Name] = stu;
        }
    }
}