ajax file asynchronous implementation of form upload-JS Tutorial-php.cn

ajax file asynchronous implementation of form upload

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Release： 2018-03-31 10:05:07

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This time I will bring you the asynchronous implementation of form upload with ajax file. What are the precautions for asynchronous implementation of form upload with ajax file? The following is a practical case, let’s take a look.

User uploads are always indispensable in projects. Here are the main list of form uploads and ajax uploads! Note: context.Request.Files is not suitable for operating large files. The following list is mainly for processing small

file uploads!

Resource download:

1. jQuery official download address:

https://jquery.com/download/

1. Form upload:

html client part:

<form action="upload.ashx" method="post" enctype="multipart/form-data">
    选择文件:<input type="file" name="file1" /><br />
    <input type="submit" value="上传" />
  </form>

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General handler server side:

public void ProcessRequest(HttpContext context)
    {
      context.Response.ContentType = "text/plain";
      HttpPostedFile file1 = context.Request.Files["file1"];
      helper.uploadFile(file1, "~/upload/");//这里就是对相应方法进行调用
      context.Response.Write("ok");//提示执行成功
    }

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Encapsulation of upload code:

/// <summary>
    /// 上传图片
    /// </summary>
    /// <param name="file">通过form表达提交的文件</param>
    /// <param name="virpath">文件要保存的虚拟路径</param>
    public static void uploadImg(HttpPostedFile file,string virpath)
    {     
      if (file.ContentLength > 1024 * 1024 * 4)
      {
        throw new Exception("文件不能大于4M");
      }
      string imgtype = Path.GetExtension(file.FileName);
      if(imgtype!=".jpg"&&imgtype!=".jpeg") //图片类型进行限制
      {
        throw new Exception("请上传jpg或JPEG图片");
      }
      using (Image img = Bitmap.FromStream(file.InputStream))
      {
        string savepath = HttpContext.Current.Server.MapPath(virpath+file.FileName);
        img.Save(savepath);
      }
    }
    /// <summary>
    /// 上传文件
    /// </summary>
    /// <param name="file">通过form表达提交的文件</param>
    /// <param name="virpath">文件要保存的虚拟路径</param>
    public static void uploadFile(HttpPostedFile file, string virpath)
    {
      if (file.ContentLength > 1024 * 1024 * 6)
      {
        throw new Exception("文件不能大于6M");
      }
      string imgtype = Path.GetExtension(file.FileName);
      //imgtype对上传的文件进行限制
      if (imgtype != ".zip" && imgtype != ".mp3")
      {
        throw new Exception("只允许上传zip、rar....文件");
      }
      string dirFullPath= HttpContext.Current.Server.MapPath(virpath);
      if (!Directory.Exists(dirFullPath))//如果文件夹不存在，则先创建文件夹
      {
        Directory.CreateDirectory(dirFullPath);
      }
      file.SaveAs(dirFullPath + file.FileName);
    }

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2. Ajax file asynchronous Upload:

Note: Since there is a form upload, why do you need ajax upload? Because during the form upload process, the entire page is refreshed! Ajax asynchronous upload can refresh only the local position. Let’s take a brief look at ajax upload!

html client part:

<head> 
<script src="jquery-2.1.4.js"></script>
 <script>
  $(function () {
   $("#upload").click(function () {
    $("#imgWait").show();
    var formData = new FormData();
    formData.append("myfile", document.getElementById("file1").files[0]); 
    $.ajax({
     url: "upload.ashx",
     type: "POST",
     data: formData,
     /**
     *必须false才会自动加上正确的Content-Type
     */
     contentType: false,
     /**
     * 必须false才会避开jQuery对 formdata 的默认处理
     * XMLHttpRequest会对 formdata 进行正确的处理
     */
     processData: false,
     success: function (data) {
      if (data.status == "true") {
       alert("上传成功！");
      }
      if (data.status == "error") {
       alert(data.msg);
      }
      $("#imgWait").hide();
     },
     error: function () {
      alert("上传失败！");
      $("#imgWait").hide();
     }
    });
   });
  });
 </script>
</head>
<body> 
  选择文件:<input type="file" id="file1" /><br />
  <input type="button" id="upload" value="上传" />
  <img src="wait.gif" style="display:none" id="imgWait" /> 
</body>

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General handler server side:

public void ProcessRequest(HttpContext context)
  {
   context.Response.ContentType = "text/html";
   if (context.Request.Files.Count > 0)
   {
    HttpPostedFile file1 = context.Request.Files["myfile"];
    helper.uploadFile(file1, "~/upload/"); //这里引用的是上面封装的方法
    WriteJson(context.Response, "true", "");
   }
   else
   {
    WriteJson(context.Response, "error", "请选择要上传的文件");
   }
  }

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json code encapsulation:

public static void WriteJson(HttpResponse response,
      string status1, string msg1, object data1 = null)
    {
      response.ContentType = "application/json";
      var obj = new { status = status1, msg = msg1, data = data1 };
      string json = new JavaScriptSerializer().Serialize(obj);
      response.Write(json);
    }

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I believe you have mastered it after reading the case in this article For more exciting methods, please pay attention to other related articles on the php Chinese website!