FileUpload 简单上传+小预览

页面代码 :

    <form id="form1" runat="server">

    <div>

        <asp:FileUpload ID="FileUpload1" runat="server" />

        <asp:Button ID="Button1" runat="server" Text="上传" Width="54px"  OnClick="Button1_Click" />

        <asp:Label ID="Label1" runat="server" Text="" Style="color: Red"></asp:Label>

       <asp:Image runat="server" ID="Image1" Style="z-index: 102; left: 20px; position: absolute;

           top: 49px" Width="73px" />

    </div>

    </form>

后台代码 :

using System;

using System.Data;

using System.Configuration;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

namespace Web.File

{

    public partial class WebForm1 : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

        }

        #region 文件上传

        /// <summary>

        /// 文件上传

        /// </summary>

        protected void Button1_Click(object sender, EventArgs e)

        {

            if (FileUpload1.FileName == "")

            {

                this.Label1.Text = "上传文件不能为空";

                return;

            }

            bool fileIsValid = false;

            //如果确认了上传文件，则判断文件类型是否符合要求

            if (this.FileUpload1.HasFile)

            {

                //获取上传文件的后缀

                String fileExtension = System.IO.Path.GetExtension(this.FileUpload1.FileName).ToLower();

                String[] restrictExtension = { ".gif", ".jpg", ".bmp", ".png" };

                //判断文件类型是否符合要求

                for (int i = ; i < restrictExtension.Length; i++)

                {

                    if (fileExtension == restrictExtension[i])

                    {

                        fileIsValid = true;

                    }

                    //如果文件类型符合要求,调用SaveAs方法实现上传,并显示相关信息

                    if (fileIsValid == true)

                    {

                        //上传文件是否大于10M

                        if (FileUpload1.PostedFile.ContentLength > ( *  * ))

                        {

                            this.Label1.Text = "上传文件过大";

                            return;

                        }

                        try

                        {

                            this.Image1.ImageUrl = "~/File/" + FileUpload1.FileName;

                            this.FileUpload1.SaveAs(Server.MapPath("~/File/") + FileUpload1.FileName);

                            this.Label1.Text = "文件上传成功!";

                        }

                        catch

                        {

                            this.Label1.Text = "文件上传失败！";

                        }

                        finally

                        {

                        }

                    }

                    else

                    {

                        this.Label1.Text = "只能够上传后缀为.gif,.jpg,.bmp,.png的文件";

                    }

                }

            }

        }

        #endregion

    }

}

Web.config 配置:

<!--因为FileUpload 控件上传最大为4M,如果要上传更大文件,改下maxRequestLength的大小-->

<configuration>

    <system.web>

        <compilation debug="true" targetFramework="4.0" />

      <httpRuntime  requestValidationMode="2.0" maxRequestLength="" executionTimeout="" appRequestQueueLimit=""/>

    </system.web>

</configuration>

效果:存在浏览器兼容问题

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