MVC4 上传图片并生成缩略图

using System;

using System.Collections.Generic;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.IO;

using System.Drawing;

using System.Web.UI.HtmlControls;

namespace MVC.Models

{

    public class upload

    {

        /// <summary>

        /// 图片上传

        /// </summary>

        /// <param name="fulFile">上传控件</param>

        /// <param name="DirectionName">文件所放的父文件夹</param>

        /// <returns>string</returns>

        public upload() { }

        /// <summary>

        /// asp.net上传图片并生成缩略图

        /// </summary>

        /// <param name="upImage">HttpPostedFileBase控件</param>

        /// <param name="sSavePath">保存的路径,些为相对服务器路径的下的文件夹</param>

        /// <param name="sThumbExtension">缩略图的thumb</param>

        /// <param name="intThumbWidth">生成缩略图的宽度</param>

        /// <param name="intThumbHeight">生成缩略图的高度</param>

        /// <returns>缩略图名称</returns>

        public string UpLoadImage(HttpPostedFileBase upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight)

        {

            string sThumbFile = "";

            string sFilename = "";

            if (upImage.FileName != null)

            {

              

                int nFileLen = upImage.ContentLength;

                if (nFileLen == 0)

                    return "没有选择上传图片";

                //获取upImage选择文件的扩展名

                string extendName = System.IO.Path.GetExtension(upImage.FileName).ToLower();

                //判断是否为图片格式

                if (extendName != ".jpg" && extendName != ".jpge" && extendName != ".gif" && extendName != ".bmp" && extendName != ".png")

                    return "图片格式不正确";

                byte[] myData = new Byte[nFileLen];

                upImage.InputStream.Read(myData, 0, nFileLen);

                sFilename = System.IO.Path.GetFileName(upImage.FileName);

                int file_append = 0;

                //检查当前文件夹下是否有同名图片,有则在文件名 1

                while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath sFilename)))

                {

                    file_append ;

                    sFilename = System.IO.Path.GetFileNameWithoutExtension(upImage.FileName)

                         file_append.ToString() extendName;

                }

                System.IO.FileStream newFile

                    = new System.IO.FileStream(System.Web.HttpContext.Current.Server.MapPath(sSavePath sFilename),

                    System.IO.FileMode.Create, System.IO.FileAccess.Write);

                newFile.Write(myData, 0, myData.Length);

                newFile.Close();

                //以上为上传原图

                try

                {

                    //原图加载

                    using (System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(sSavePath sFilename)))

                    {

                        //原图宽度和高度

                        int width = sourceImage.Width;

                        int height = sourceImage.Height;

                        int smallWidth;

                        int smallHeight;

                        //获取第一张绘制图的大小,(比较 原图的宽/缩略图的宽  和 原图的高/缩略图的高)

                        if (((decimal)width) / height <= ((decimal)intThumbWidth) / intThumbHeight)

                        {

                            smallWidth = intThumbWidth;

                            smallHeight = intThumbWidth * height / width;

                        }

                        else

                        {

                            smallWidth = intThumbHeight * width / height;

                            smallHeight = intThumbHeight;

                        }

                        //判断缩略图在当前文件夹下是否同名称文件存在

                        file_append = 0;

                        sThumbFile = sThumbExtension System.IO.Path.GetFileNameWithoutExtension(upImage.FileName) extendName;

                        while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath sThumbFile)))

                        {

                            file_append ;

                            sThumbFile = sThumbExtension System.IO.Path.GetFileNameWithoutExtension(upImage.FileName)

                                file_append.ToString() extendName;

                        }

                        //缩略图保存的绝对路径

                        string smallImagePath = System.Web.HttpContext.Current.Server.MapPath(sSavePath) sThumbFile;

                        //新建一个图板,以最小等比例压缩大小绘制原图

                        using (System.Drawing.Image bitmap = new System.Drawing.Bitmap(smallWidth, smallHeight))

                        {

                            //绘制中间图

                            using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))

                            {

                                //高清,平滑

                                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

                                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

                                g.Clear(Color.Black);

                                g.DrawImage(

                                sourceImage,

                                new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight),

                                new System.Drawing.Rectangle(0, 0, width, height),

                                System.Drawing.GraphicsUnit.Pixel

                                );

                            }

                            //新建一个图板,以缩略图大小绘制中间图

                            using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight))

                            {

                                //绘制缩略图

                                using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1))

                                {

                                    //高清,平滑

                                    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

                                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

                                    g.Clear(Color.Black);

                                    int lwidth = (smallWidth - intThumbWidth) / 2;

                                    int bheight = (smallHeight - intThumbHeight) / 2;

                                    g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel);

                                    g.Dispose();

                                    bitmap1.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg);

                                }

                            }

                        }

                    }

                }

                catch

                {

                    //出错则删除

                    System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath sFilename));

                    return "图片格式不正确";

                }

                //返回缩略图名称

                return sThumbFile;

            }

            return "没有选择图片";

        }

    }

}