c# Detailed introduction of the algorithm for applying NPOI to obtain pictures in Excel and save them locally

private string exclePath = @"C:\users\lenovo\Desktop\testPic.xls";
 private void button2_Click(object sender, EventArgs e)
 {
 List<string> listpath = new List<string>{};
 string savePath = Path.Combine("E:\\","pic"); 
 if(!Directory.Exists(savePath))//判断是否存在保存文件夹，没有则新建
 Directory.CreateDirectory(savePath);
 bool result = ExcelToImage(exclePath, savePath, ref listpath);
 if(result)
 MessageBox.Show("导出成功");
 else
 MessageBox.Show("导出失败");
 }

/// <summary>
 /// 从excel获取图片
 /// </summary>
 /// <param name="filepath">文件路径</param>
 /// <param name="savepath">图片保存路径</param>
 /// <param name="listPath">返回保存的图表地址list</param>
 /// <returns>保存图片是否成功</returns>
 private bool ExcelToImage(string filepath,string savepath,ref List<string> listPath)
 {
 try
 {
 using (FileStream fsReader = File.OpenRead(filepath))
 {
  HSSFWorkbook wk = new HSSFWorkbook(fsReader);
  IList pictures = wk.GetAllPictures();
  int i = 0;
  foreach (HSSFPictureData pic in pictures)
  {
  //if (pic.Data.Length == 19504) //跳过不需要保存的图片，其中pic.data有图片长度
  // continue;
  string ext = pic.SuggestFileExtension();//获取扩展名
  string path = string.Empty;
  if (ext.Equals("jpg"))
  {
  Image jpg = Image.FromStream(new MemoryStream(pic.Data));//从pic.Data数据流创建图片
  path = Path.Combine(savepath, string.Format("pic{0}.jpg", i++));
  jpg.Save(path);//保存
  }
  else if (ext.Equals("png"))
  {
  Image png = Image.FromStream(new MemoryStream(pic.Data));
  path = Path.Combine(savepath, string.Format("pic{0}.png", i++));
  png.Save(path);
  }
  if (!string.IsNullOrEmpty(path))
  listPath.Add(path);
  }
 }
 }
 catch (Exception ex)
 {
 return false;
 
 }
 return true;
 }