Question

我正在尝试预览用户尝试上传的图片。这是我正在使用的代码。这在所有主流浏览器中运行良好，但我想知道是否有更好的方法来实现这一点而不使用会话（即使我正在清除会话）？我不想使用Flash。

   @using (Html.BeginForm("UploadImage", "Home", FormMethod.Post, new { id = "fileuploadform", @enctype = "multipart/form-data" }))
    {
        <input id="fileupload" type="file" onchange="ChangeImage()" name="files" multiple>
        <div id="preview">
            <img src="#" id="imgThumbnail" alt="preview" />
        </div>

    }
            <script>
            $(function ChangeImage() {
                $('#fileuploadform').fileupload({
                    done: function (e, data) {
                        var d = new Date();
                        $('#imgThumbnail')[0].src = "/Home/ImageLoad?a=" + d.getTime();
                    }
                });
            });
        </script>

[HttpPost]
public ActionResult UploadImage(IEnumerable<HttpPostedFileBase> files, PostViewModel model)
{

    Session["ContentLength"] = Request.Files[0].ContentLength;
    Session["ContentType"] = Request.Files[0].ContentType;
    byte[] b = new byte[Request.Files[0].ContentLength];
    Request.Files[0].InputStream.Read(b, 0, Request.Files[0].ContentLength);
    Session["ContentStream"] = b;
    return Content(Request.Files[0].ContentType + ";" + Request.Files[0].ContentLength);
}

   public ActionResult ImageLoad(int? id)
    {
        byte[] b = (byte[])Session["ContentStream"];
        int length = (int)Session["ContentLength"];
        string type = (string)Session["ContentType"];
        Session["ContentLength"] = null;
        Session["ContentType"] = null;
        Session["ContentStream"] = null;
        return File(b, type);
    }

Answer 1

你试过这个解决方案吗？

Preview an image before it is uploaded

此解决方案纯粹是客户端，在预览之前无需上传到您的服务器。：）

Answer 2

您可以通过以下方式改进操作代码：

HttpPostedFileBase picFile = Request.Files["fileUpload"];
if (picFile != null && picFile.ContentLength > 0)
{
     byte[] pic = new byte[picFile.ContentLength];
     picFile.InputStream.Read(pic, 0, picFile.ContentLength);
     // you can use pic ....
}

Answer 3

使用Fileupload Asp.Net C＃MVC和Razor Framework和jQuery预览图像吗？

这将一次预览多个文件作为缩略图。

使用Razor Framework的View Asp.Net C＃MVC

<div class="form-group">
   @Html.LabelFor(model => model.ImageMedias)
   <div class="input-group">
      <div class="custom-file">
         @Html.TextBoxFor(model => model.ImageMedias, "", new { @class = "custom-file-input", @type = "file", @multiple = "multiple", @accept = ".jfif,.jpg,.jpeg,.png,.gif" })
         <label class="custom-file-label" for="InputFile">Choose file</label>
      </div>
   </div>
   @Html.ValidationMessageFor(model => model.ImageMedias)   
   <div id="divImageMediaPreview">
   </div>
</div>

脚本

$("#ImageMedias").change(function () {
    if (typeof (FileReader) != "undefined") {
        var dvPreview = $("#divImageMediaPreview");
        dvPreview.html("");            
        $($(this)[0].files).each(function () {
            var file = $(this);                
                var reader = new FileReader();
                reader.onload = function (e) {
                    var img = $("<img />");
                    img.attr("style", "width: 150px; height:100px; padding: 10px");
                    img.attr("src", e.target.result);
                    dvPreview.append(img);
                }
                reader.readAsDataURL(file[0]);                
        });
    } else {
        alert("This browser does not support HTML5 FileReader.");
    }
});

我希望这会有所帮助。

使用Fileupload asp.net mvc和Jquery预览图像

3 个答案: