这两种方法目前如果遇到0开头的数据，会默认把0去掉，可以考虑如果StartsWith(“0”)，则在前面加个单引号（即’）
不推荐Excel导出，因为Excel2003一个Sheet最多导出65535条，Excel2007是10万4000多条，数据量大会报错，所以推荐使用CSV导出

• 导出 Excel

  /// <summary>
  /// 将 DataTable 转换为 Excel
  /// 需在 nuget 安装 DotNetCore.NPOI
  /// </summary>
  /// <param name="table">数据表</param>
  /// <param name="sheetName">sheet名称</param>
  /// <returns></returns>
  public static byte[] DataTableToExcel(DataTable table, string title = null, string sheetName = "Sheet")
  {
      try
      {
          IWorkbook workbook = new XSSFWorkbook();
          ISheet sheet = workbook.CreateSheet(sheetName);
          int cellsIndex = 0;
          // 标题
          if (!string.IsNullOrEmpty(title))
          {
              // 填充数据
              IRow cellsTitle = sheet.CreateRow(0);
              cellsTitle.CreateCell(0).SetCellValue(title);
              // 合并单元格
              sheet.AddMergedRegion(new NPOI.SS.Util.CellRangeAddress(0, 1, 0, table.Columns.Count - 1));
              cellsIndex = 2;
          }
          // 填充表头
          IRow cellsHeader = sheet.CreateRow(cellsIndex);
          for (int i = 0; i < table.Columns.Count; i++)
          {
              cellsHeader.CreateCell(i).SetCellValue(table.Columns[i].ColumnName);
          }
          // 填充数据
          cellsIndex += 1;
          foreach (DataRow dr in table.Rows)
          {
              IRow row = sheet.CreateRow(cellsIndex);
              for (int i = 0; i < table.Columns.Count; i++)
              {
                  row.CreateCell(i).SetCellValue(StrHelper.ToString(dr[i]));
              }
              cellsIndex++;
          }
          byte[] buffer = null;
          using (MemoryStream ms = new MemoryStream())
          {
              workbook.Write(ms);
              buffer = ms.GetBuffer();
              ms.Close();
          }
          return buffer;
      }
      catch (Exception)
      {
          return null;
      }
  }	
  

• 导出 CSV

  /// <summary>
  /// 将 DataTable 转换为 CSV
  /// </summary>
  /// <param name="table">数据表</param>
  /// <returns></returns>
  public static Stream DataTableToCsv(DataTable table)
  {
      try
      {
          StringBuilder builder = new StringBuilder();
          DataColumn column;
          int iColCount = table.Columns.Count;
          // 处理表头
          for (int i = 0; i < iColCount; i++)
          {
              if (i != 0) builder.Append(",");
              builder.Append("\"" + table.Columns[i].ColumnName + "\"");
          }
          builder.AppendLine();
          // 处理内容
          foreach (DataRow row in table.Rows)
          {
              for (int i = 0; i < iColCount; i++)
              {
                  column = table.Columns[i];
                  if (i != 0) builder.Append(",");
                  if (Convert.IsDBNull(row[column])) builder.Append("\"\"");
                  //else if (row[column].ToString().StartsWith("0")) builder.Append("\"'" + row[column].ToString() + "\"");
                  else builder.Append("\"" + row[column].ToString() + "\"");
              }
              builder.AppendLine();
          }
          byte[] bytes = Encoding.GetEncoding("GB2312").GetBytes(builder.ToString());
          Stream stream = new MemoryStream(bytes);
          return stream ;
      }
      catch (Exception)
      {
          return null;
      }
  }
  

• .Net Core WebAPI Controller

  /// <summary>
  /// 导出 Excel
  /// </summary>
  /// <returns></returns>
  [HttpGet("exportExcel")]
  public async Task<IActionResult> ExportExcel()
  {
      DataTable dataTable = new DataTable(); // 此处准备 dataTable 数据
      
      string name = "数据详情";
      byte[] bytes = Utils.DataTableToExcel(dataTable, name, name);
      return File(bytes, "application/octet-stream", $"{name}_{DateTime.Now:yyyyMMddHHmmssfff}.xlsx");
  }
  
  /// <summary>
  /// 导出 CSV
  /// </summary>
  /// <returns></returns>
  [HttpGet("exportCSV")]
  public async Task<IActionResult> ExportCSV()
  {
      DataTable dataTable = new DataTable(); // 此处准备 dataTable 数据
  
      System.IO.Stream stream = Utils.DataTableToCsv(dataTable);
      return File(stream, "application/octet-stream", $"数据详情_{DateTime.Now:yyyyMMddHHmmssfff}.csv");
  }
  

• .Net Core Startup.cs 配置
  这里配置 .WithExposedHeaders("Content-Disposition")
是因为 Vue Axios response.headers 中默认获取不到 content-disposition 属性
  点击此处查看microsoft官方文档

  public void ConfigureServices(IServiceCollection services)
  {
  	// ......
  	
      // 处理 api 请求跨域
      services.AddCors(options =>
      {
          options.AddPolicy("cors",
              builder =>
              {
                  builder.AllowAnyMethod()
                  .AllowAnyOrigin()
                  .AllowAnyHeader()
                  .WithExposedHeaders("Content-Disposition");
              });
      });
  
  	// ......
  }
  

• Vue Axios

  service.interceptors.response.use(
    response => {
      // blob 直接返回文件流数据
      if (response.config.responseType === 'blob') {
        console.log(response.headers);
        const fileName = decodeURI(
        	// response.headers['content-disposition'] 默认获取不到，需要在 .Net Core Startup.cs 中进行配置
          response.headers['content-disposition'].split('filename*=UTF-8\'\'')[1]
        )
        return Promise.resolve({ data: response.data, fileName: fileName })
      }
  
      // ......
    },
    error => {
      return Promise.reject(error)
    }
  )
  

• Vue 请求接口

  export function exportCSV(param) {
      return request({
          url: '/controller/exportCSV',
          method: 'get',
          params: { ...param },
          responseType: 'blob'
      })
  }
  

• Vue 下载实现

  export default {
    data() {
      return {
        listQuery: {},
      };
    },
    created() {},
    methods: {
      // 导出报表
      onExport() {
        exportCSV(this.listQuery).then((response) => {
          let blob = new Blob([response.data], { type: response.data.type });
          // 针对于 IE 浏览器的处理, 因部分 IE 浏览器不支持 createObjectURL
          if (window.navigator && window.navigator.msSaveOrOpenBlob) {
            window.navigator.msSaveOrOpenBlob(blob, response.fileName);
          } else {
            var downloadElement = document.createElement("a");
            var href = window.URL.createObjectURL(blob); // 创建下载的链接
            downloadElement.href = href;
            downloadElement.download = response.fileName; // 下载后文件名
            document.body.appendChild(downloadElement);
            downloadElement.click(); // 点击下载
            document.body.removeChild(downloadElement); // 下载完成移除元素
            window.URL.revokeObjectURL(href); // 释放掉 blob 对象
          }
        });
      },
    },
  };