asp.net上传图片并生成缩略图

前台代码:
<%@ Page language="c#" Codebehind="TestWebForm.aspx.cs" AutoEventWireup="false" Inherits="Example.TestWebForm" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <title>在ASP.NET里轻松实现缩略图</title>
        <meta content="Microsoft Visual Studio.NET 7.0" name="GENERATOR">
        <meta content="Visual Basic 7.0" name="CODE_LANGUAGE">
        <meta content="JavaScript" name="vs_defaultClientScript">
        <meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema">
    </HEAD>
    <body MS_POSITIONING="GridLayout">
        <asp:label id="Label1" runat="server"></asp:label>
        <form id="Form1" method="post" encType="multipart/form-data" runat="server">
            <INPUT type="file" name="file" width="600"><br>
            <br>
            <asp:Button id="Button1" runat="server"></asp:Button></form>
    </body>
</HTML>

后台代码:

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.IO; 
using System.Drawing.Imaging;

namespace Example
{
    /// <summary>
    /// TestWebForm 的摘要说明。
    /// </summary>
    public class TestWebForm : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.Label Label1;
        protected System.Web.UI.WebControls.Button Button1;

        private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            Label1.Text = "<h3>在ASP.NET里轻松实现缩略图</h3>"; 
            Button1.Text = "上载并显示缩略图"; 

        }

        Web 窗体设计器生成的代码

        private void Button1_Click(object sender, System.EventArgs e)
        {
            HttpFileCollection MyFileColl = HttpContext.Current.Request.Files;   //获取客户端上载的文件（多部件 MIME 格式）集合
            HttpPostedFile MyPostedFile = MyFileColl[0];  //获取第一个文件

            if (MyPostedFile.ContentType.ToString().ToLower().IndexOf("image") < 0) 
            { 
                Response.Write("无效的图形格式。"); 
                return; 
            } 
            GetThumbNail(MyPostedFile.FileName, 100, 100, 
                MyPostedFile.ContentType.ToString(), false, MyPostedFile.InputStream); 
        }

        /// <summary>
        /// 得到图片的类型
        /// </summary>
        /// <param name="strContentType"></param>
        /// <returns></returns>
        private System.Drawing.Imaging.ImageFormat GetImageType(object strContentType) 
        { 
            if ((strContentType.ToString().ToLower()) == "image/pjpeg") 
            { 
                return System.Drawing.Imaging.ImageFormat.Jpeg; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/gif") 
            { 
                return System.Drawing.Imaging.ImageFormat.Gif; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/bmp") 
            { 
                return System.Drawing.Imaging.ImageFormat.Bmp; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/tiff") 
            { 
                return System.Drawing.Imaging.ImageFormat.Tiff; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/x-icon") 
            { 
                return System.Drawing.Imaging.ImageFormat.Icon; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/x-png") 
            { 
                return System.Drawing.Imaging.ImageFormat.Png; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/x-emf") 
            { 
                return System.Drawing.Imaging.ImageFormat.Emf; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/x-exif") 
            { 
                return System.Drawing.Imaging.ImageFormat.Exif; 
            } 
            else if ((strContentType.ToString().ToLower()) == "image/x-wmf") 
            { 
                return System.Drawing.Imaging.ImageFormat.Wmf; 
            } 
            else 
            { 
                return System.Drawing.Imaging.ImageFormat.MemoryBmp; 
            } 
        } 

        /// <summary>
        /// 得到缩略图
        /// </summary>
        /// <param name="strFileName">文件名</param>
        /// <param name="iWidth">宽度</param>
        /// <param name="iheight">高度</param>
        /// <param name="strContentType"></param>
        /// <param name="blnGetFromFile">是否从文件创建Image对象</param>
        /// <param name="ImgStream"></param>
        private void GetThumbNail(string strFileName, int iWidth, int iheight, 
            string strContentType, bool blnGetFromFile, System.IO.Stream ImgStream) 
        { 
            System.Drawing.Image oImg;
        
            if (blnGetFromFile) 
            { 
                oImg = System.Drawing.Image.FromFile(strFileName); 
            } 
            else 
            { 
                oImg = System.Drawing.Image.FromStream(ImgStream); 
            } 
            oImg = oImg.GetThumbnailImage(iWidth, iheight, null, IntPtr.Zero);   //GetThumbnailImage方法是返回此Image对象的缩略图
            string strGuid = System.Guid.NewGuid().ToString().ToUpper();  //初始化 Guid 类的新实例
            string strFileExt = strFileName.Substring(strFileName.LastIndexOf("."));  //得到图片的后缀
            Response.ContentType = strContentType; 
            MemoryStream MemStream = new MemoryStream(); //创建其支持存储区为内存的流
            oImg.Save(MemStream, GetImageType(strContentType)); 
            MemStream.WriteTo(Response.OutputStream);  //WriteTo方法是将此内存流的整个内容写入另一个流中
        } 
    }
}
posted @ 2006-09-28 10:59  MSDI  阅读(420)  评论(0)  编辑  收藏  举报