1、aspx页面代码：
UploadPic.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="UploadPic.aspx.cs" Inherits="Pic_Try.UploadPic" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>图片上传和显示</title>
<style type="text/css">
.pic_text{ color:Red;}
.pic_label { color:Gray; margin-top:5px; margin-bottom:5px;}
.pic_image { margin:5px;}
</style>
</head>
<body>
<form id="form1" runat="server">
<div class="pic_image"><asp:Image ID="pic" runat="server" /></div>
<div><asp:FileUpload ID="pic_upload" runat="server" /><asp:Label ID="lbl_pic" runat="server" class="pic_text"></asp:Label></div>
<div class="pic_label">上传图片格式为.jpg, .gif, .bmp,.png,图片大小不得超过8M</div>
<div><asp:Button ID="btn_upload" runat="server" Text="上传" onclick="btn_upload_Click"/></div>
</form>
</body>
</html>
2.后台代码
UploadPic.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Security.Cryptography;
using System.Web.Security;
namespace Pic_Try
{
public partial class UploadPic : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btn_upload_Click(object sender, EventArgs e)
{
Boolean fileOk = false;
if (pic_upload.HasFile)//验证是否包含文件
{
//取得文件的扩展名,并转换成小写
string fileExtension = Path.GetExtension(pic_upload.FileName).ToLower();
//验证上传文件是否图片格式
fileOk = IsImage(fileExtension);
if (fileOk)
{
//对上传文件的大小进行检测，限定文件最大不超过8M
if (pic_upload.PostedFile.ContentLength < 8192000)
{
string filepath = "/images/";
if (Directory.Exists(Server.MapPath(filepath)) == false)//如果不存在就创建file文件夹
{
Directory.CreateDirectory(Server.MapPath(filepath));
}
string virpath = filepath + CreatePasswordHash(pic_upload.FileName, 4) + fileExtension;//这是存到服务器上的虚拟路径
string mappath = Server.MapPath(virpath);//转换成服务器上的物理路径
pic_upload.PostedFile.SaveAs(mappath);//保存图片
//显示图片
pic.ImageUrl = virpath;
//清空提示
lbl_pic.Text = "";
}
else {
pic.ImageUrl = "";
lbl_pic.Text = "文件大小超出8M！请重新选择！";
}
}
else {
pic.ImageUrl = "";
lbl_pic.Text = "要上传的文件类型不对！请重新选择！";
}
}
else
{
pic.ImageUrl = "";
lbl_pic.Text = "请选择要上传的图片！";
}
}
/// <summary>
/// 验证是否指定的图片格式
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
public bool IsImage(string str) {
bool isimage = false;
string thestr = str.ToLower();
//限定只能上传jpg和gif图片
string[] allowExtension = { ".jpg", ".gif", ".bmp",".png" };
//对上传的文件的类型进行一个个匹对
for (int i = 0; i < allowExtension.Length; i++)
{
if (thestr == allowExtension[i])
{
isimage = true;
break;
}
}
return isimage;
}
/// <summary>
/// 创建一个指定长度的随机salt值
/// </summary>
public string CreateSalt(int saltLenght)
{
//生成一个加密的随机数
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
byte[] buff = new byte[saltLenght];
rng.GetBytes(buff);
//返回一个Base64随机数的字符串
return Convert.ToBase64String(buff);
}
/// <summary>
/// 返回加密后的字符串
/// </summary>
public string CreatePasswordHash(string pwd, int saltLenght)
{
string strSalt = CreateSalt(saltLenght);
//把密码和Salt连起来
string saltAndPwd = String.Concat(pwd, strSalt);
//对密码进行哈希
string hashenPwd = FormsAuthentication.HashPasswordForStoringInConfigFile(saltAndPwd, "sha1");
//转为小写字符并截取前16个字符串
hashenPwd = hashenPwd.ToLower().Substring(0, 16);
//返回哈希后的值
return hashenPwd;
}
}
}
3.最后防止上传大文件图片时报错，配置文件添加配置
Web.config
<?xml version="1.0" encoding="utf-8"?>
<!--
有关如何配置 ASP.NET 应用程序的详细消息，请访问
http://go.microsoft.com/fwlink/?LinkId=169433
-->
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.0" />
<httpRuntime executionTimeout="240" maxRequestLength="8192000"/>
</system.web>
</configuration>