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(已测)【ASP.NET 基础】图片上传和显示

2016-01-10 16:52 826 查看

下面是代码：

1.界面代码

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"?>



<configuration>

<system.web>

<compilation debug="true" targetFramework="4.0" />

<httpRuntime executionTimeout="240" maxRequestLength="8192000"/>

</system.web>

</configuration>

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