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

         <asp:FileUpload ID="FileUpload1" runat="server" accept=".jpg,.jpeg,.png" />

         <asp:Button ID="Button1" runat="server" Text="上传" />

         <asp:Image ID="Image1" runat="server"  />

     </form>

 <script>

     document.getElementById("Button1").onclick = function () {

         var f = document.getElementById("FileUpload1");

         if (f.value.length <= )//没有选择上传的文件

         {

             alert("请选择上传的文件！");

             return false;

         }

         if (f.files[].size > ( *  * ))//限制上传文件的大小10MB

         {

             alert("文件过大，不允许上传！");

             return false;

         }

     };

 </script>

 using System.Drawing;//绘画引用System.Drawing命名空间

 protected void Page_Load(object sender, EventArgs e)

     {

         Button1.Click+=Button1_Click;//上传按钮

     }

     void Button1_Click(object sender, EventArgs e)

     {

         //2.创建System.Drawing.Image对象，使用FromStream方法需要System.IO对象

         System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent);

        //1.绘画用Graphics这个类，使用FromImage方法指向画布，需要System.Drawing.Image对象

        Graphics g = Graphics.FromImage(img);

        //4 创建s-绘制的内容 f-字体 b-画刷

        string s = "www.baidu.com";

        Font f = new Font("黑体", );

        Brush b = new SolidBrush(Color.Red);

        //3.绘制DrawString方法 s-绘制的内容 f-字体 b-画刷 从哪个位置开始画

        g.DrawString(s, f, b, , );

        //5保存img.Save 制作保存路径

        string path = "Images/" + DateTime.Now.ToString("yyyyMMddhhssmm") + FileUpload1.FileName;

        img.Save(Server.MapPath(path));

         //页面展示图片

        Image1.ImageUrl = path;

     }