c#图片上传和显示的实现方法

2020-01-24 00:57:59

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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：

具体实现代码如下：

1.界面代码

<%@ 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>

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