.NET Core 文件的上传与下载

1.前言

　　　文件导入导出是简单且常用的功能，以下示例实现了文件上传与下载的几种方法，如有不妥的地方，欢迎指正。小白一枚，在往目标前进。

2.1.文件上传    --    纯文件

 <form action="/Home/Index" method ="post" enctype="multipart/form-data" >
     <input type="file" multiple/>
     <input id="upload" type="submit" />
 </form>

    [HttpPost]
         public IActionResult Index(List<IFormFile> files)
         {
                         foreach (var file in files)
             {
                 //获取文件名
                 var fileName = file.FileName;
                 //保存在wwwroot文件夹下
                 fileName = hostingEnv.WebRootPath + $"\\{fileName}";                 using (FileStream fs = System.IO.File.Create(fileName))
                 {
                     file.CopyTo(fs);
                     fs.Flush();
                 }
             }
             return View();
         }

2.2.文件上传    --    多类型内容上传

对于这种不只有文件的表单，可以采用模型绑定的方式。

 <form action="/Home/Index" method ="post" enctype="multipart/form-data" > 
     <input type="file" multiple/>
     <input type="text" name="Name"/>
     <input id="upload" type="submit" /> 
 </form>

        /// <summary>
        /// 表单上传文件
        /// </summary>
        /// <param name="files"></param>
        /// <returns></returns>
        [HttpPost]
        public IActionResult Index(FormObject obj)
        {
            foreach (var file in obj.Files)
            {
                //获取文件名
                var fileName = ContentDispositionHeaderValue
                                .Parse(file.ContentDisposition)
                                .FileName
                                .Trim('"');
                fileName = hostingEnv.WebRootPath + $"\\{fileName}";
                using (FileStream fs = System.IO.File.Create(fileName))
                {
                    file.CopyTo(fs);
                    fs.Flush();
                }
            }
            return View();
        }

//模型类
public class FormObject

{
       public List<IFormFile> Files{ get; set; }
       public string Name { get; set; }
}

2.3.文件上传  -- Ajax上传

    <input type="text" name="Name" value="123"/>
    <input type="file" id="fileUpload" name="fileUpload" multiple/>
    <input id="upload" type="button" value="ajax 提交"/>

<script type="text/javascript">
    $(function () {
        $("#upload").click(function (evt) {
            ///取选择的文件加入FormData中
            var fileUpload = $("#fileUpload").get(0);
            var files = fileUpload.files;
            var data = new FormData();
            for (var i = 0; i < files.length; i++) {
                data.append(files[i].name, files[i]);
            }
           // data.append("Name", $('input[name="Name"]').val())
            $.ajax({
                type: "POST",
                url: "http://192.168.0.175:8095/api/Organization",
                contentType: false,
                processData: false,
                data: data,
                success: function (message) {
                    alert(message);
                },
                error: function () {
                    alert("上传文件出现错误！");
                }
            });
        });
    });
</script>

        /// <summary>
        /// 通过ajax上传
        /// </summary>
        /// <returns></returns>
        public IActionResult UploadFiles()
        {var files = Request.Form.Files;
            var value =Request.Form.First(c => c.Key == "Name").Value;//获得表单文本项
            foreach (var file in files)
            {
                var fileName = file.FileName;
                fileName = hostingEnv.WebRootPath + $@"\{fileName}";using (FileStream fs = System.IO.File.Create(fileName))
                {
                    file.CopyTo(fs);
                    fs.Flush();
                }
            }
            return RedirectToAction("/Export", new { Title ="",Name = });
        }

3.3.文件下载

        [HttpGet]
         public IActionResult ExportText()
         {

             string sFileName = $@"qmhuangtext{DateTime.Now.ToString("yyyyMMddHHmmss")}.txt";
             FileStream fs =new FileStream(sFileName,FileMode.OpenOrCreate);
             StreamWriter sw = new StreamWriter(fs);
             sw.WriteLine("Hello world");
             sw.Flush();
             sw.Close();
             fs.Close();
             return File(new FileStream(sFileName, FileMode.Open), "application/octet-stream", $"导出测试{DateTime.Now.ToString("yyyyMMddHHmmss")}.txt");
         }