HTML5上传文件显示进度

       下面我们使用Html 5的新特性file api实现上传文件，并显示上传文件进度百分比。意图是这样的，当选择文件时，显示当前文件信息。这里我们是结合Asp.net
MVC做为服务端，您也可以是其它的服务端语言。让我们看面这个片断的HTML：
      

@using (Html.BeginForm("Upload", "Home", FormMethod.Post, new { enctype = "multipart/form-data" , id="form1"}))

{

<div class="row">

<label for="file">

Upload Image:</label>

<input type="file" name="fileToUpload" id="fileToUpload"  multiple="multiple" onchange="fileSelected();" />

</div>

<div id="fileName">

</div>

<div id="fileSize">

</div>

<div id="fileType">

</div> 

<div class="row">

    <input type="button" onclick="uploadFile()" value="Upload Image" />

</div>

<div id="progressNumber">

</div>

}

相关的Javascript是这样的： 

function fileSelected() {

    var file = document.getElementById('fileToUpload').files[0];

    if (file) {

var fileSize = 0;

if (file.size > 1024 * 1024)

    fileSize = (Math.round(file.size * 100 / (1024 * 1024)) / 100).toString() + 'MB';

else

    fileSize = (Math.round(file.size * 100 / 1024) / 100).toString() + 'KB';

document.getElementById('fileName').innerHTML = 'Name: ' + file.name;

document.getElementById('fileSize').innerHTML = 'Size: ' + fileSize;

document.getElementById('fileType').innerHTML = 'Type: ' + file.type;

}

}

function uploadFile() {

    var fd = new FormData();

    fd.append("fileToUpload", document.getElementById('fileToUpload').files[0]);

    var xhr = new XMLHttpRequest();

    xhr.upload.addEventListener("progress", uploadProgress, false);

    xhr.addEventListener("load", uploadComplete, false);

    xhr.addEventListener("error", uploadFailed, false);

    xhr.addEventListener("abort", uploadCanceled, false);

    xhr.open("POST", "Home/Upload");

    xhr.send(fd);

}

function uploadProgress(evt) {

    if (evt.lengthComputable) {

var percentComplete = Math.round(evt.loaded * 100 / evt.total);

document.getElementById('progressNumber').innerHTML = percentComplete.toString() + '%';

}

    else {

document.getElementById('progressNumber').innerHTML = 'unable to compute';

}

}

function uploadComplete(evt) {

    /* This event is raised when the server send back a response */

    alert(evt.target.responseText);

}

function uploadFailed(evt) {

    alert("There was an error attempting to upload the file.");

}

function uploadCanceled(evt) {

    alert("The upload has been canceled by the user or the browser dropped the connection.");

}

上面是就原生的Javascript，在onchange事件执行fileSelected的function，在点击button执行了uploadFile的function，这里使用XMLHttpRequest实现ajax上传文件。 注意代码在Firefox
14 可以工作，IE 9目前不支持file api，可以参加这里。 服务端的代码很简单： 

public class HomeController : Controller

{

public ActionResult Index()

{

    return View();

}

/// <summary>

/// Uploads the specified files.

/// </summary>

/// <param name="fileToUpload">The files.</param>

/// <returns>ActionResult</returns>

[HttpPost]

public ActionResult Upload(HttpPostedFileBase[] fileToUpload)

{

    foreach (HttpPostedFileBase file in fileToUpload)

{

string path = System.IO.Path.Combine(Server.MapPath("~/App_Data"), System.IO.Path.GetFileName(file.FileName));

file.SaveAs(path);

}

    ViewBag.Message = "File(s) uploaded successfully";

    return RedirectToAction("Index");

}

}

希望对您Web开发有帮助。您可能感兴趣文章: 

用Html5与Asp.net MVC上传多个文件