原文地址：https://www.cnblogs.com/luckyting/articles/10563288.html#

前端代码#

 handlePopTrainClassStudents(index,row) {
      let link = document.createElement('a');
      link.style.display = 'none';
      link.href = 'http://localhost:15811/api/'+this.api['GetStudentInfoExcel']+'?tcId='+row.TC_ID;
      link.setAttribute('download','true');
      link.setAttribute('target','_blank')
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
    },

控制器#

  public HttpResponseMessage GetStudentInfoExcel(int tcId)
        {
        FilesMake fm = new FilesMake();
        var stream = fm.ExportStudentByTcIdData(tcId);

        if (stream == null)
        {
            return new HttpResponseMessage(HttpStatusCode.NoContent);
        }

        try
        {
            HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
            result.Content = new StreamContent(stream);
            result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.ms-excel");
            result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
            TrainClasses tc = db.TrainClasses.Find(tcId);
            result.Content.Headers.ContentDisposition.FileName = $"{tc.TC_Name}班学生详情-{System.DateTime.Now.ToString("yyyyMMddHHmmss")}.xls";
            return result;
        }
        catch
        {
            return new HttpResponseMessage(HttpStatusCode.NoContent);
        }
    }

处理代码#

 public System.IO.Stream ExportStudentByTcIdData(int tcId)
    {
    #region 生成xls
    var lstTitle = new List<string> { "学生编号", "校区班级编号", "学号", "姓名", "姓名拼音",
        "性别", "身份证号", "学生状态", "已通过认证","学历","专业","毕业学校","个人手机","家庭坐机","QQ号",
        "通信地址","邮编","学历费","技能培养费","实训住宿费" ,"技术评价","班主任评价","备注","最终选择的岗位","选岗次数"};//,
    IWorkbook book = new HSSFWorkbook();
    ISheet sheet = book.CreateSheet("sheet1");
    IRow rowTitle = sheet.CreateRow(0);
    ICellStyle style = book.CreateCellStyle();
    style.VerticalAlignment = NPOI.SS.UserModel.VerticalAlignment.Center;//垂直居中
    for (int i = 0; i < lstTitle.Count; i++)
    {
        rowTitle.CreateCell(i).SetCellValue(lstTitle[i]);
    }

    var list = (from tcs in db.TrainClassStudents
                join stu in db.Students on tcs.Student_ID equals stu.Student_ID into tcs_stu_tmp
                from tcs_stu in tcs_stu_tmp.DefaultIfEmpty()
                join tc in db.TrainClasses on tcs.TC_ID equals tc.TC_ID into tcs_stu_tc_tmp
                from tcs_stu_tc in tcs_stu_tc_tmp.DefaultIfEmpty()
        where tcs_stu_tc.TC_ID == tcId
        select new
        {
            tcs_stu.Student_ID,
            tcs_stu.Student_Name,
            tcs_stu.SC_ID,
            tcs_stu.Student_NO,
            tcs_stu.Student_NameSpell,
            tcs_stu.Student_Sex,
            tcs_stu.Student_IdentityNumber,
            tcs_stu.Student_State,
            tcs_stu.Student_Exam,
            tcs_stu.Student_Education,
            tcs_stu.Student_Specialty,
            tcs_stu.Student_Schoolofgraduation,
            tcs_stu.Student_PersonalTel,
            tcs_stu.Student_FamilyTel,
            tcs_stu.Student_QQ,
            tcs_stu.Student_Address,
            tcs_stu.Student_PostCode,
            tcs_stu.Student_EducationMoney,
            tcs_stu.Student_SkillTrainingMoney,
            tcs_stu.Student_TrainResideMoney,
            tcs_stu.Student_Evaluate1,
            tcs_stu.Student_Evaluate2,
            tcs_stu.Student_Remark,
            tcs_stu.Station_ID,
            tcs_stu.Stationt_SelectStationCount
        }).ToList();
    if (list.Count > 0)
    {
        list.OrderByDescending(o => o.Student_ID);
        int start = 0;//记录同组开始行号
        int end = 0;//记录同组结束行号
        string temp = "";//记录上一行的值
        for (int i = 0; i < list.Count; i++)
        {
            IRow row = sheet.CreateRow(i + 1);
            row.CreateCell(0).SetCellValue(list[i].Student_ID);
            row.CreateCell(1).SetCellValue(list[i].SC_ID??0);
            row.CreateCell(2).SetCellValue(list[i].Student_NO);
            row.CreateCell(3).SetCellValue(list[i].Student_Name);
            row.CreateCell(4).SetCellValue(list[i].Student_NameSpell);
            row.CreateCell(5).SetCellValue(list[i].Student_Sex);
            row.CreateCell(6).SetCellValue(list[i].Student_IdentityNumber);
            row.CreateCell(7).SetCellValue(list[i].Student_State);
            row.CreateCell(8).SetCellValue(list[i].Student_Exam);
            row.CreateCell(9).SetCellValue(list[i].Student_Education);
            row.CreateCell(10).SetCellValue(list[i].Student_Specialty);
            row.CreateCell(11).SetCellValue(list[i].Student_Schoolofgraduation);
            row.CreateCell(12).SetCellValue(list[i].Student_PersonalTel);
            row.CreateCell(13).SetCellValue(list[i].Student_FamilyTel);
            row.CreateCell(14).SetCellValue(list[i].Student_QQ);
            row.CreateCell(15).SetCellValue(list[i].Student_Address);
            row.CreateCell(16).SetCellValue(list[i].Student_PostCode);
            row.CreateCell(17).SetCellValue(list[i].Student_EducationMoney);
            row.CreateCell(18).SetCellValue(list[i].Student_SkillTrainingMoney);
            row.CreateCell(19).SetCellValue(list[i].Student_TrainResideMoney);
            row.CreateCell(20).SetCellValue(list[i].Student_Evaluate1);
            row.CreateCell(21).SetCellValue(list[i].Student_Evaluate2);
            row.CreateCell(22).SetCellValue(list[i].Student_Remark);
            row.CreateCell(23).SetCellValue(list[i].Station_ID??0);
            row.CreateCell(24).SetCellValue(list[i].Stationt_SelectStationCount??0);

            row.GetCell(0, MissingCellPolicy.CREATE_NULL_AS_BLANK).SetCellType(CellType.String);
            var cellText = row.Cells[0].StringCellValue;//获取当前行 第1列的单元格的值

            if (cellText == temp)//上下行相等，记录要合并的最后一行
            {
                end = i;
            }
            else//上下行不等，记录
            {
                if (start != end)
                {
                    //设置一个合并单元格区域，使用上下左右定义CellRangeAddress区域
                    //CellRangeAddress四个参数为：起始行，结束行，起始列，结束列
                    CellRangeAddress region = new CellRangeAddress(start + 1, end + 1, 0, 0);
                    sheet.AddMergedRegion(region);
                }
                start = i;
                end = i;
                temp = cellText;
            }
        }
    }

    #endregion
    for (int i = 0; i < lstTitle.Count; i++)
    {
        sheet.AutoSizeColumn(i);//i：根据标题的个数设置自动列宽
    }

    MemoryStream ms = new MemoryStream();
    book.Write(ms);
    ms.Seek(0, SeekOrigin.Begin);
    return ms;
}