【ASP.NET 基础】图片上传和显示

原文地址为： 【ASP.NET 基础】图片上传和显示

由于需要图片上传的功能，所以花了一些时间网上找相关资料终于搞定，效果图如下：

下面的是解决方案截图和上传的图片截图：

 

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" %>

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

"http://www.w3.org/1999/xhtml">
"server">
    
    


    
"form1" runat="server">
    
class="pic_image">"pic" runat="server" />
    
"pic_upload" runat="server" />"lbl_pic" runat="server" class="pic_text">
    
class="pic_label">上传图片格式为.jpg, .gif, .bmp,.png,图片大小不得超过8M
    
"btn_upload" runat="server"  Text="上传" οnclick="btn_upload_Click"/>
    

 

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！";
            }
        }

/// 

/// 验证是否指定的图片格式
/// 
/// 
/// 
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;
        }

/// 

/// 创建一个指定长度的随机salt值
/// 
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);
        }


/// 

/// 返回加密后的字符串
/// 
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

"1.0" encoding="utf-8"?>




    
      "true" targetFramework="4.0" />
      "240" maxRequestLength="8192000"/>
    

 

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