ASP.NET上传图片文件

using System;
using System.IO;

public partial class _Default : System.Web.UI.Page
{
    protected void btnUpload_Click(object sender, EventArgs e)
    {
        if(IsPostBack)
        {
            Boolean fileOK = false;//定义变量判断文件是否为图片
            String path = Server.MapPath("~/UploadedImages/");//指定文件保存路径

            if (fuUpload.HasFile) //判断控件是否选择文件
            {
                String fileExtension = Path.GetExtension(fuUpload.FileName).ToLower();//使用该方法得到上传文件的扩展名
                String[] allowedExtensions = {".gif", ".png", ".jpeg", ".jpg"};//定义允许上传的扩展名

                for (int i = 0; i < allowedExtensions.Length; i++)
                {
                   if (fileExtension == allowedExtensions[i])//如果上传文件通过检测
                   {
                        fileOK = true;//将该变量设值为true
                   }
                }
            }

            if (fileOK)//判断是否通过检测
            {
                try
                {
                    if (!Directory.Exists(path))//使用Directory类的方法判断保存路径目录是否存在
                    {
                        Directory.CreateDirectory(path);//如果不存在便创建该目录
                    }
                    fuUpload.PostedFile.SaveAs(path + fuUpload.FileName);
                    Label1.Text = "File uploaded!";
                }
                catch(Exception ex)
                {
                    Label1.Text = "File could not be uploaded." + ex.Message;
                }
            }
            else
            {
                Label1.Text = "Cannot accept files of this type.";
            }
        }
        string strFileName = fuUpload.FileName;
    }
}

HTML_Code:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">