在MVC 4中上载/显示图像

任何人都知道有关如何使用实体框架从数据库上载/显示图像的分步教程吗？我已经检查了代码片段，但是我仍然不清楚它是如何工作的。我没有代码，因为除了编写上传表单之外，我也迷路了。任何（我的意思是任何）帮助都将不胜感激。

在旁注中，为什么没有书籍涵盖这一主题？我同时拥有Pro ASP.NET MVC 4和Professional MVC4，他们没有提及它。

看看以下

@using (Html.BeginForm("FileUpload", "Home", FormMethod.Post, 
                            new { enctype = "multipart/form-data" }))
{  
    <label for="file">Upload Image:</label> 
    <input type="file" name="file" id="file" style="width: 100%;" /> 
    <input type="submit" value="Upload" class="submit" /> 
}

您的控制器应该有可以接受的动作方法HttpPostedFileBase;

 public ActionResult FileUpload(HttpPostedFileBase file)
    {
        if (file != null)
        {
            string pic = System.IO.Path.GetFileName(file.FileName);
            string path = System.IO.Path.Combine(
                                   Server.MapPath("~/images/profile"), pic); 
            // file is uploaded
            file.SaveAs(path);

            // save the image path path to the database or you can send image 
            // directly to database
            // in-case if you want to store byte[] ie. for DB
            using (MemoryStream ms = new MemoryStream()) 
            {
                 file.InputStream.CopyTo(ms);
                 byte[] array = ms.GetBuffer();
            }

        }
        // after successfully uploading redirect the user
        return RedirectToAction("actionname", "controller name");
    }

更新1

如果您想异步使用jQuery上传文件，请尝试使用本文。

处理服务器端（用于多次上传）的代码是；

 try
    {
        HttpFileCollection hfc = HttpContext.Current.Request.Files;
        string path = "/content/files/contact/";

        for (int i = 0; i < hfc.Count; i++)
        {
            HttpPostedFile hpf = hfc[i];
            if (hpf.ContentLength > 0)
            {
                string fileName = "";
                if (Request.Browser.Browser == "IE")
                {
                    fileName = Path.GetFileName(hpf.FileName);
                }
                else
                {
                    fileName = hpf.FileName;
                }
                string fullPathWithFileName = path + fileName;
                hpf.SaveAs(Server.MapPath(fullPathWithFileName));
            }
        }

    }
    catch (Exception ex)
    {
        throw ex;
    }

此控件还返回图像名称（在javascript回调中），然后您可以使用它在DOM中显示图像。

更新2

或者，您可以尝试在MVC 4中进行异步文件上传。

这是一个简短的教程：

模型：

namespace ImageUploadApp.Models
{
    using System;
    using System.Collections.Generic;

    public partial class Image
    {
        public int ID { get; set; }
        public string ImagePath { get; set; }
    }
}

视图：

1. 创建：

   @model ImageUploadApp.Models.Image
   @{
       ViewBag.Title = "Create";
   }
   <h2>Create</h2>
   @using (Html.BeginForm("Create", "Image", null, FormMethod.Post, 
                                 new { enctype = "multipart/form-data" })) {
       @Html.AntiForgeryToken()
       @Html.ValidationSummary(true)
       <fieldset>
           <legend>Image</legend>
           <div class="editor-label">
               @Html.LabelFor(model => model.ImagePath)
           </div>
           <div class="editor-field">
               <input id="ImagePath" title="Upload a product image" 
                                     type="file" name="file" />
           </div>
           <p><input type="submit" value="Create" /></p>
       </fieldset>
   }
   <div>
       @Html.ActionLink("Back to List", "Index")
   </div>
   @section Scripts {
       @Scripts.Render("~/bundles/jqueryval")
   }
   

2. 索引（用于显示）：

   @model IEnumerable<ImageUploadApp.Models.Image>
   
   @{
       ViewBag.Title = "Index";
   }
   
   <h2>Index</h2>
   
   <p>
       @Html.ActionLink("Create New", "Create")
   </p>
   <table>
       <tr>
           <th>
               @Html.DisplayNameFor(model => model.ImagePath)
           </th>
       </tr>
   
   @foreach (var item in Model) {
       <tr>
           <td>
               @Html.DisplayFor(modelItem => item.ImagePath)
           </td>
           <td>
               @Html.ActionLink("Edit", "Edit", new { id=item.ID }) |
               @Html.ActionLink("Details", "Details", new { id=item.ID }) |
               @Ajax.ActionLink("Delete", "Delete", new {id = item.ID} })
           </td>
       </tr>
   }
   
   </table>
   

3. 控制器（创建）

   public ActionResult Create(Image img, HttpPostedFileBase file)
   {
       if (ModelState.IsValid)
       {
           if (file != null)
           {
               file.SaveAs(HttpContext.Server.MapPath("~/Images/") 
                                                     + file.FileName);
               img.ImagePath = file.FileName;
           }  
           db.Image.Add(img);
           db.SaveChanges();
           return RedirectToAction("Index");
       }
       return View(img);
   }
   

希望这会有所帮助:)

        <input type="file" id="picfile" name="picf" />
       <input type="text" id="txtName" style="width: 144px;" />
 $("#btncatsave").click(function () {
var Name = $("#txtName").val();
var formData = new FormData();
var totalFiles = document.getElementById("picfile").files.length;

                    var file = document.getElementById("picfile").files[0];
                    formData.append("FileUpload", file);
                    formData.append("Name", Name);

$.ajax({
                    type: "POST",
                    url: '/Category_Subcategory/Save_Category',
                    data: formData,
                    dataType: 'json',
                    contentType: false,
                    processData: false,
                    success: function (msg) {

                                 alert(msg);

                    },
                    error: function (error) {
                        alert("errror");
                    }
                });

});

 [HttpPost]
    public ActionResult Save_Category()
    {
      string Name=Request.Form[1]; 
      if (Request.Files.Count > 0)
        {
            HttpPostedFileBase file = Request.Files[0];
         }


    }