MiniExcel简介
简单、高效避免OOM的.NET处理Excel查、写、填充数据工具。目前主流框架大多需要将数据全载入到内存方便操作，但这会导致内存消耗问题，MiniExcel 尝试以 Stream 角度写底层算法逻辑，能让原本1000多MB占用降低到几MB，避免内存不够情况。

特点：
1.低内存耗用，避免OOM、频繁 Full GC 情况
2.支持即时操作每行数据
3.兼具搭配 LINQ 延迟查询特性，能办到低消耗、快速分页等复杂查询
4.轻量，不需要安装 Microsoft Office、COM+，DLL小于150KB
5.简便操作的 API 风格
项目地址：mini-software/MiniExcel: Fast, Low-Memory, Easy Excel .NET helper to import/export/template spreadsheet (support Linux, Mac) (github.com)

安装 MiniExcel

导出数据

 public class Student
  {
      public string? Name { get; set; }
      public string? Home { get; set; }
      public int? Age {  get; set; }   
  }

 //获得当前目录的路径
 string currentDirectory = Directory.GetCurrentDirectory();
 // 堆代码 duidaima.com
 //合并当前目录与Excel文件名
 var path = Path.Combine(currentDirectory, $"{Guid.NewGuid()}.xlsx");
 
  List<Student> studentList = new List<Student>()
  {
      new Student { Name = "小东", Home = "New York", Age = 25 },
      new Student { Name = "小西", Home = "London", Age = 22 },
      new Student { Name = "小南", Home = "Paris", Age = 28 },
      new Student { Name = "小北", Home = "Tokyo", Age = 24 },
      new Student { Name = "小王", Home = "Berlin", Age = 26 }
 };

MiniExcel.SaveAs(path, studentList);

导入Excel中如下图所示：

但是目前还不支持Excel的插入：

因此如果遇到不仅仅只是生成Excel，后续还要向Excel添加数据的需求，可以用csv代替：

 //获得当前目录的路径
 string currentDirectory = Directory.GetCurrentDirectory();
 // 堆代码 duidaima.com
 //合并当前目录与CSV文件名
 var path = Path.Combine(currentDirectory, $"{Guid.NewGuid()}.csv");

 List<Student> studentList = new List<Student>()
  {
      new Student { Name = "小东", Home = "New York", Age = 25 },
      new Student { Name = "小西", Home = "London", Age = 22 },
      new Student { Name = "小南", Home = "Paris", Age = 28 },
      new Student { Name = "小北", Home = "Tokyo", Age = 24 },
      new Student { Name = "小王", Home = "Berlin", Age = 26 }
 };

 MiniExcel.SaveAs(path, studentList);

生成的CSV文件如下图所示：

向CSV文件继续添加数据：

  //获得当前目录的路径
  string currentDirectory = Directory.GetCurrentDirectory();

  //合并当前目录与Excel文件名
  //var path = Path.Combine(currentDirectory, $"{Guid.NewGuid()}.csv");
  var path = Path.Combine(currentDirectory, "10de09bb-ad8c-4430-b717-5f24117a11a6.csv");

  List<Student> studentList = new List<Student>()
   {
       new Student { Name = "小东", Home = "New York", Age = 25 },
       new Student { Name = "小西", Home = "London", Age = 22 },
       new Student { Name = "小南", Home = "Paris", Age = 28 },
       new Student { Name = "小北", Home = "Tokyo", Age = 24 },
       new Student { Name = "小王", Home = "Berlin", Age = 26 }
  };

  //MiniExcel.SaveAs(path, studentList);
  MiniExcel.Insert(path, studentList);

继续添加数据后的CSV文件如下图所示：

导入数据

 var path = "你的文件路径";
 var rows = MiniExcel.Query<Student>(path);

实现效果如下所示：