.Net 上传文件和下载文件

一、上传文件

　　1、普通的form表单提交

　　注意点：

1. 请求方式必须为Post。
2. form表单里必须设置enctype属性(enctype = "multipart/form-data")

下面的代码是实现Demo：　　

<div class="row">
    @using(Html.BeginForm("Export", "Home", FormMethod.Post, new { @class = "form-horzoontal", @enctype = "multipart/form-data" }))
    {
        <div class="form-group">
            <label class="label-control">请选择文件</label>
            <div class="col-md-4">
                @Html.TextBox("File","", new { @type="file",@class="form-ontrol"})
            </div>
        </div>
        <div class="form-group">
            <div class="clearfix">
                <button type="submit" class="btn btn-primary">
                    <i class="icon-ok"></i>提交
                </button>
                <button type="reset" class="btn btn-danger">
                    <i class="icon-undo"></i>重置
                </button>
            </div>
        </div>
    }
</div> 

/// <summary>
        /// 提交文件
        /// </summary>
        [HttpPost]
        public void Export(HttpPostedFileBase File)
        {
            //HttpFileCollection files = System.Web.HttpContext.Current.Request.Files;
            //HttpPostedFile file = files[0];
            //拓展名
            string Extension = System.IO.Path.GetExtension(File.FileName);
            //文件名
            string FileName = DateTime.Now.ToFileTime() + Extension;
            //文件存放路径
            string Path = Server.MapPath("~/upload/");
            //如果文件路径不存在 
            if (!System.IO.Directory.Exists(Path))
            {
                System.IO.Directory.CreateDirectory(Path);
            }

            File.SaveAs(Path + "//" + FileName);
        }

　　2、Ajax表单提交 

　　注意点：

1. 导入jquery.unobtrusive-ajax.min.js和jquery.form.js两个引用。
2. 提交的时候必须用 $("#form").ajaxSubmit()的提交方式。否则接收不到文件流。 

　　下面的代码是实现Demo：

<div class="row">
    @using(Ajax.BeginForm("Export", "Home", null,new AjaxOptions { HttpMethod="Post"}, new {@id="form", @class = "form-horzoontal", @enctype = "multipart/form-data" }))
    {
        <div class="form-group">
            <label class="label-control">请选择文件</label>
            <div class="col-md-4">
                @Html.TextBox("File","", new { @type="file",@class="form-ontrol"})
            </div>
        </div>
        <div class="form-group">
            <div class="clearfix">
                <button type="button" class="btn btn-primary" onclick="sub()">
                    <i class="icon-ok"></i>提交
                </button>
                <button type="reset" class="btn btn-danger">
                    <i class="icon-undo"></i>重置
                </button>
            </div>
        </div>
    }
</div> 
@section Scripts{
<script src="~/Scripts/jquery-1.8.2.min.js"></script> 
<script src="~/Scripts/jquery.form.js"></script> 
<script src="~/Scripts/jquery.unobtrusive-ajax.min.js"></script>
<script>
    //ajax提交表单
    function sub() {
        $("#form").ajaxSubmit();  
    }
</script>
}

/// <summary>
        /// 提交文件
        /// </summary>
        [HttpPost]
        public void Export(HttpPostedFileBase File)
        {
            //HttpFileCollection files = System.Web.HttpContext.Current.Request.Files;
            //HttpPostedFile file = files[0];
            //拓展名
            string Extension = System.IO.Path.GetExtension(File.FileName);
            //文件名
            string FileName = DateTime.Now.ToFileTime() + Extension;
            //文件存放路径
            string Path = Server.MapPath("~/upload/");
            //如果文件路径不存在 
            if (!System.IO.Directory.Exists(Path))
            {
                System.IO.Directory.CreateDirectory(Path);
            }

            File.SaveAs(Path + "//" + FileName);
        }

 二、下载文件

　　下面是两种实现方式

　　1、

/// <summary>
        /// 下载文件
        /// </summary>
        public void DownloadFile()
        {
            //获取respone对象
            HttpResponse respone = System.Web.HttpContext.Current.Response;
            //文件绝对路径
            string Path = Server.MapPath("~/upload/131348099436645924.JPG");
            string fileName = System.IO.Path.GetFileName(Path);
            System.IO.FileInfo file = new FileInfo(Path); 
            Response.AddHeader("Content-Disposition", "attachment;filename="" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + """);
            Response.AddHeader("Content-Length", file.Length.ToString()); 
            //响应类型
            Response.ContentType = "application/octet-stream";
            Response.WriteFile(Path);
            Response.Flush();
            Response.End();
        }

　　2、

/// <summary>
        /// 下载文件
        /// </summary>
        public FileResult DownloadFile()
        { 
            //文件绝对路径
            string Path = Server.MapPath("~/upload/131348099436645924.JPG");
            string fileName = System.IO.Path.GetFileName(Path);
            return File(Path, "application/octet-stream",fileName);
        }