说明：开发环境 vs2012 mvc4项目，后台语言csharp
1、前端代码
<html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/><title>图片上传测试</title></head><body><form action="/Home/MultiSavePage" enctype="multipart/form-data" method="post"> <input type="file" name="files" id="file1" onchange="checkPic(this)" /><br/> <input type="file" name="files" id="file2" onchange="checkPic(this)"/><br/> <input type="file" name="files" id="file3" onchange="checkPic(this)"/><br/> <input type="submit" value="同时上传多个文件" /> </form> <script type="text/javascript">function checkPic(e) { if (!e || !e.value) return;var patn = /\.jpg$|\.jpeg$|\.png$|\.gif$/i;if (!patn.test(e.value)) {alert("您选择的似乎不是图像文件。");e.value = "";return;}else {//以下的代码可以 把选中的图片 放到img中显示var $file = $(e);var fileObj = $file[0];var windowURL = window.URL || window.webkitURL;var dataURL; //var $img = $("#"+id+"");if (fileObj && fileObj.files && fileObj.files[0]) {dataURL = windowURL.createObjectURL(fileObj.files[0]);console.log(dataURL);//$img.attr(‘src‘, dataURL);}}}</script></body></html>2、控制器代码
action="/Home/MultiSavePage" 对应的后台代码
（1）、正常保存图片，不对图片压缩处理
???????public void MultiSavePage(IEnumerable<HttpPostedFileBase> files) ???????{ ???????????Int32 count = files.Count(); ???????????Int32 pid = 56; ???????????Int32 offid = 100; ???????????string str = "GX"; ????????????????string pathForSaving = Server.MapPath("~/img"); ???????????string pagePath = pathForSaving + "/" + offid + "/" + str + "/" + pid; ???????????if (this.CreateFolderIfNeeded(pagePath)) ???????????{ ???????????????foreach (var file in files) ???????????????{ ???????????????????if (file != null && file.ContentLength > 0) ???????????????????{ ?????????????????????????????????string[] picName = file.FileName.Split(‘.‘); ???????????????????????//判断文件的类型 ???????????????????????if (picName[1] == "jpg" || picName[1] == "gif" || picName[1] == "png" || picName[1] == "bmg" || picName[1] == "jpeg") ???????????????????????{ ??????????????????????????????????????????????????//给上传文件重命名 ???????????????????????????string filename = DateTime.Now.ToString("yyyyMMddHHmmssfff") + Guid.NewGuid().ToString(); ??????????????????????????//文件保存的路径 ???????????????????????????string filesavepath = ?filename + "." + picName[1]; ???????????????????????????//保存图片 ???????????????????????????//var path = Path.Combine(pathForSaving, file.FileName); ???????????????????????????var path = Path.Combine(pagePath, filename + "." + picName[1]); ???????????????????????????file.SaveAs(path); ???????????????????????} ??????????????????????????????????????} ???????????????} ???????????} ??????????????????}注释：
string pathForSaving = Server.MapPath("~/img"); img是项目文件夹，上传的图片都保存到img文件夹下
（2）、对上传的图片压缩处理，并且把图片保存为png格式
??public void MultiSavePage(IEnumerable<HttpPostedFileBase> files) ???????{ ???????????Int32 count = files.Count(); ???????????Int32 pid = 56; ???????????Int32 offid = 100; ???????????string str = "GX"; ????????????????string pathForSaving = Server.MapPath("~/img"); ???????????string pagePath = pathForSaving + "/" + offid + "/" + str + "/" + pid; ???????????if (this.CreateFolderIfNeeded(pagePath)) ???????????{ ???????????????foreach (var file in files) ???????????????{ ???????????????????if (file != null && file.ContentLength > 0) ???????????????????{ ?????????????????????????????????string[] picName = file.FileName.Split(‘.‘); ???????????????????????//判断文件的类型 ???????????????????????if (picName[1] == "jpg" || picName[1] == "gif" || picName[1] == "png" || picName[1] == "bmg" || picName[1] == "jpeg") ???????????????????????{ ??????????????????????????????????????????????????//给上传文件重命名 ???????????????????????????string filename = DateTime.Now.ToString("yyyyMMddHHmmssfff") + Guid.NewGuid().ToString(); ??????????????????????????//文件保存的路径 ???????????????????????????string filesavepath = ?filename + "." + picName[1]; ???????????????????????????//保存图片 ???????????????????????????//var path = Path.Combine(pathForSaving, file.FileName); ???????????????????????????var path = Path.Combine(pagePath, filename + "." + picName[1]); ???????????????????????????//file.SaveAs(path); ???????????????????????????Bitmap bitmapTem = (Bitmap)Image.FromStream(file.InputStream);//file图片文件转换为bitmap ??????????????????????????????????????????????????????????????????????????????//压缩图片 ???????????????????????????Bitmap bitmapLast = ZoomImage(bitmapTem, 331, 600); ???????????????????????????bitmapLast.Save(path, System.Drawing.Imaging.ImageFormat.Png); ???????????????????????} ??????????????????????????????????????} ???????????????} ???????????} ??????????????????}
3、用到的其他方法
?????// 检查是否要创建上传文件夹 ????????private bool CreateFolderIfNeeded(string path) ???????{ ???????????bool result = true; ???????????if (!Directory.Exists(path)) ???????????{ ???????????????try ???????????????{ ???????????????????Directory.CreateDirectory(path); ???????????????} ???????????????catch (Exception) ???????????????{ ???????????????????//TODO:处理异常 ????????????????????result = false; ???????????????} ???????????} ???????????return result; ???????} 4、压缩图片的方法
using System.Drawing;
???//等比例缩放图片 ???????//destHeight 331 destWidth 600 ???????private Bitmap ZoomImage(Bitmap bitmap, int destHeight, int destWidth) ???????{ ???????????try ???????????{ ???????????????System.Drawing.Image sourImage = bitmap; ???????????????int width = 0, height = 0; ???????????????//按比例缩放 ??????????????????????????int sourWidth = sourImage.Width; ???????????????int sourHeight = sourImage.Height; ???????????????if (sourHeight > destHeight || sourWidth > destWidth) ???????????????{ ???????????????????if ((sourWidth * destHeight) > (sourHeight * destWidth)) ???????????????????{ ???????????????????????width = destWidth; ???????????????????????height = (destWidth * sourHeight) / sourWidth; ???????????????????} ???????????????????else ???????????????????{ ???????????????????????height = destHeight; ???????????????????????width = (sourWidth * destHeight) / sourHeight; ???????????????????} ???????????????} ???????????????else ???????????????{ ???????????????????width = sourWidth; ???????????????????height = sourHeight; ???????????????} ???????????????Bitmap destBitmap = new Bitmap(destWidth, destHeight); ???????????????Graphics g = Graphics.FromImage(destBitmap); ???????????????g.Clear(Color.Transparent); ???????????????//设置画布的描绘质量 ????????????????????????g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; ???????????????g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; ???????????????g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; ???????????????g.DrawImage(sourImage, new Rectangle((destWidth - width) / 2, (destHeight - height) / 2, width, height), 0, 0, sourImage.Width, sourImage.Height, GraphicsUnit.Pixel); ???????????????g.Dispose(); ???????????????//设置压缩质量 ????????????????????System.Drawing.Imaging.EncoderParameters encoderParams = new System.Drawing.Imaging.EncoderParameters(); ???????????????long[] quality = new long[1]; ???????????????quality[0] = 100; ???????????????System.Drawing.Imaging.EncoderParameter encoderParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality); ???????????????encoderParams.Param[0] = encoderParam; ???????????????sourImage.Dispose(); ???????????????return destBitmap; ???????????} ???????????catch ???????????{ ???????????????return bitmap; ???????????} ???????}html5 file 上传图片
原文地址：https://www.cnblogs.com/net064/p/10234602.html