asp.net(C#)上传单个图片并判断图片的类型和大小

第一步，新建文件upload.aspx
 第二步，在upload.aspx的设计页面里放入<asp:FileUpload ID="ImgUpload" runat="server" />控件和button控件，button控件的单击代码如下.
 第三步，写代码，代码如下：
 if (ImgUpload.FileName != null)
 {
 string ImgName = ImgUpload.FileName;
 string ImgExtention = System.IO.Path.GetExtension(ImgName);
 int ImgSize = ImgUpload.PostedFile.ContentLength;//此处取得的文件大小的单位是byte
 string ImgPath = Server.MapPath("~/upload_files/works/");//此处是你的项目下的文件夹
 string ImgUrl = "upload_files/works/" + ImgName;//This is for the saving in the sql.
 if (ImgExtention == ".gif" || ImgExtention == ".GIF" || ImgExtention == ".jpg" || ImgExtention == ".JPG" || ImgExtention == ".jpeg" || ImgExtention == ".JPEG")
 {
 if (ImgSize / 1024 < 1024)//转换为kb
 {
 ImgUpload.PostedFile.SaveAs(ImgPath + ImgName);                    
ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('上传图片成功！');</script>");
 }
 else
 {
 ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('图片大小不能超过1M！');</script>");
 }
 }
 else
 {
 ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('图片格式不正确，只支持.gif/.jpg/.jpeg格式类型的图片！');</script>");
 }
 }
 else
 {
 ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('请选择要上传的图片！');</script>");
 }