ASP.NET C#上传图片生成缩略图

资料原自网络，本人小小修改一下，备注以后使用。

CS代码 

  1  /// <summary> 
  2     /// asp.net上传图片并生成缩略图 
  3     /// </summary> 
  4     /// <param name="upImage">HtmlInputFile控件</param> 
  5     /// <param name="sSavePath">保存的路径,些为相对服务器路径的下的文件夹</param> 
  6     /// <param name="sThumbExtension">缩略图的thumb</param> 
  7     /// <param name="intThumbWidth">生成缩略图的宽度</param> 
  8     /// <param name="intThumbHeight">生成缩略图的高度</param> 
  9     /// <returns>缩略图名称</returns> 
 10     public string UpLoadImage(HtmlInputFile upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight)
 11     {
 12         #region
 13         #region
 14         string sThumbFile = "";
 15         string sFilename = "";
 16         if (txtTitle.Text.Trim().Length > 0)
 17         {
 18         }
 19         else
 20         {
 21             Jscript.Alert("标题不能为空");
 22             return "标题不能为空";
 23         }
 24         School.Model.BlogUserPic bumodel = new School.Model.BlogUserPic();
 25         School.BLL.BlogUserPic buBll = new School.BLL.BlogUserPic();
 26 
 27         //获取用户ID
 28         EncryptStr Encry = new EncryptStr();
 29         userID = Encry.Decrypt(HttpContext.Current.Request.Cookies["SchoolStudent"]["UserID"].ToString());
 30 
 31         //设置添加信息
 32         bumodel.PicTitle = Utils.ChkSQL(this.txtTitle.Text.Trim().ToString());
 33         bumodel.PicDesc = Utils.ChkSQL(this.txtPicDesc.Text.Trim().ToString());
 34         bumodel.addTime = DateTime.Now;
 35         bumodel.UserId = Utils.StrToInt(userID, 0);
 36         bumodel.uploadIP = DNTRequest.GetIP();
 37         bumodel.IsDel = 0;
 38         bumodel.IsCheck = 1;
 39         #endregion
 40         #region
 41         if (upImage.PostedFile != null)
 42         {
 43             HttpPostedFile myFile = upImage.PostedFile;
 44             int nFileLen = myFile.ContentLength;
 45             if (nFileLen == 0)
 46             {
 47                 Jscript.Alert("没有选择上传图片");
 48                 return "没有选择上传图片";
 49             }
 50             if (nFileLen > 2097152)
 51             {
 52                 Jscript.Alert("上传图片不能大于2MB");
 53                 return "上传图片不能大于2MB";
 54             }
 55             //获取upImage选择文件的扩展名
 56             string extendName = System.IO.Path.GetExtension(myFile.FileName).ToLower();
 57             //判断是否为图片格式
 58             if (extendName != ".jpg" && extendName != ".jpge" && extendName != ".gif" && extendName != ".bmp" && extendName != ".png")
 59             {
 60                 Jscript.Alert("图片格式不正确");
 61                 return "图片格式不正确";
 62             }
 63             byte[] myData = new Byte[nFileLen];
 64             myFile.InputStream.Read(myData, 0, nFileLen);
 65             sFilename = System.IO.Path.GetFileName(myFile.FileName);
 66             int file_append = 0;
 67             //检查当前文件夹下是否有同名图片,有则在文件名+1
 68             while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))
 69             {
 70                 file_append++;
 71                 sFilename = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName)
 72              + file_append.ToString() + extendName;
 73             }
 74             System.IO.FileStream newFile = new System.IO.FileStream(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename),
 75                 System.IO.FileMode.Create, System.IO.FileAccess.Write);
 76             newFile.Write(myData, 0, myData.Length);
 77             newFile.Close();
 78             //以上为上传原图
 79             #region
 80             try
 81             {
 82                 //原图加载
 83                 using (System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))
 84                 {
 85                     //原图宽度和高度
 86                     int width = sourceImage.Width;
 87                     int height = sourceImage.Height;
 88                     int smallWidth;
 89                     int smallHeight;
 90                     //获取第一张绘制图片的大小,(比较 原图的宽/缩略图的宽 和 原图的高/缩略图的高)
 91                     if (((decimal)width) / height <= ((decimal)intThumbWidth) / intThumbHeight)
 92                     {
 93                         smallWidth = intThumbWidth;
 94                         smallHeight = intThumbWidth * height / width;
 95                     }
 96                     else
 97                     {
 98                         smallWidth = intThumbHeight * width / height;
 99                         smallHeight = intThumbHeight;
100                     }
101 
102                     //判断缩略图在当前文件夹下是否同名称文件存在
103                     file_append = 0;
104                     sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + extendName;
105                     while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)))
106                     {
107                         file_append++;
108                         sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + file_append.ToString() + extendName;
109                     }
110 
111                     //缩略图保存的绝对路径
112                     string smallImagePath = Server.MapPath(sSavePath) + sThumbFile;
113                     //System.Web.HttpContext.Current.Server.MapPath(sSavePath) + sThumbFile;
114                     //bumodel.PicUrl = Server.MapPath(smallImagePath);
115                     bumodel.PicUrl = "/UploadBlogPhoto/" + userID + "/" + sThumbFile;//压缩过的图片
116                     //smallImagePath;
117                     //业务层 增加方法 bumodel是model
118                     buBll.Add(bumodel);//添加相片
119                     Response.Write("<script language='JavaScript'>alert('添加相片成功');window.location='BlogUserPic.aspx?userID=" + userID + "';</script>");
120                     //Response.End();
121                     //新建一个图板,以最小等比例压缩大小绘制原图
122                     using (System.Drawing.Image bitmap = new System.Drawing.Bitmap(smallWidth, smallHeight))
123                     {
124                         //绘制中间图
125                         using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))
126                         {
127                             //高清,平滑
128                             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
129                             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
130                             g.Clear(System.Drawing.Color.White);
131                             g.DrawImage(
132                                 sourceImage, new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight),
133                                 new System.Drawing.Rectangle(0, 0, width, height), System.Drawing.GraphicsUnit.Pixel);
134                         }
135                         //新建一个图板，以缩略图大小绘制中间图
136                         using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight))
137                         {
138                             //绘制缩略图
139                             using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1))
140                             {
141                                 //高清,平滑
142                                 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
143                                 g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
144                                 g.Clear(System.Drawing.Color.White);
145                                 int lwidth = (smallWidth - intThumbHeight) / 2;
146                                 int bheight = (smallHeight - intThumbHeight) / 2;
147                                 g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel);
148                                 g.Dispose();
149                                 bitmap1.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg);
150                             }
151                         }
152                     }
153 
154                 }
155             }
156 
157             catch
158             {
159                 //出错则删除 
160                 System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename));
161                 Jscript.Alert("图片格式不正确");
162                 return "图片格式不正确";
163             }
164             #endregion
165             //返回缩略图名称 
166             return sThumbFile;
167         }
168         #endregion
169         Jscript.Alert("没有选择图片");
170         return "没有选择图片";
171         #endregion
172     }

 

CS button控件事件

 1   /// <summary>
 2     /// 上传图片事件
 3     /// </summary>
 4     /// <param name="sender">sender</param>
 5     /// <param name="e">e</param>
 6     protected void btnSmbit_Click(object sender, EventArgs e)
 7     {
 8         //获取用户ID
 9         EncryptStr Encry = new EncryptStr();
10         userID = Encry.Decrypt(HttpContext.Current.Request.Cookies["SchoolStudent"]["UserID"　　　　　　　].ToString());
11         //我们是根据用户ID生成一个文件夹，保存到单独的文件夹
12         this.UpLoadImage(this.File1, "../UploadBlogPhoto/" + userID + "/", "thumb_", 600, 600);
13     }

 

 前台代码

　　　　<td>

                添加相片：

                <input id="File1" runat="server" type="file" />        

 　　　　　　<asp:Button ID="btnSmbit" runat="server" Text="提交" OnClick="btnSmbit_Click" /> 

            </td>

 

转载于:https://www.cnblogs.com/LeeYongze/archive/2010/05/27/1745206.html

来源：https://blog.csdn.net/weixin_30664615/article/details/99272880