asp.net fileupload 实现上传

protected void Button1_Click(object sender, EventArgs e)
{
string filename = this.DropDownList1.SelectedValue;//最终命名
if (this.FileUpload1.PostedFile != null)
{
string baseFilename = this.FileUpload1.PostedFile.FileName;//获取上传文件文件名
int i = baseFilename.LastIndexOf(".");
string ext = baseFilename.Substring(i);//获取文件的扩展名
string savePath = Server.MapPath("~/pic/");
if (!System.IO.Directory.Exists(savePath))
{
System.IO.Directory.CreateDirectory(savePath );
}
savePath = savePath + "\\" + filename+ext;
//Response.Write(ext );
if (!ext.Equals(".jpg") && !ext.Equals(".jpeg") && !ext.Equals(".bmp") && !ext.Equals(".gif") && !ext.Equals(".png"))
{
Response.Write("上传文件格式不正确！<a href="\" href="\""upload.aspx\">重新上传</a>");
Response.End();
}

FileUpload1.PostedFile.SaveAs( savePath );
}
}