文件 API 文件上传 - 在 ASP.NET MVC 中读取 XMLHttpRequest

Question

我正在尝试在 ASP.NET MVC 中实现 Gmail 样式的拖放文件上传。

我一直在关注这篇文章：http://robertnyman.com/html5/fileapi-upload/fileapi-upload.html 并希望将上传的文件发布到 MVC 控制器操作。

为此，我修改了链接中的示例 JavaScript 脚本以指向我的控制器操作：

xhr.open("post", "/home/UploadFiles", true);

这是我的控制器操作：

[HttpPost]
public virtual string UploadFiles(object obj)
{
    var length = Request.ContentLength;
    var bytes = new byte[length];
    Request.InputStream.Read(bytes, 0, length);
    // var bytes has byte content here. what do do next?

    return "Files uploaded!";
}

我设置了一个断点，当我上传一个文件时，断点被命中——这很好。但是如何从上传的（javascript）XMLHttpRequest 对象中提取数据？我不认为它在 HttpRequest - 它是参数吗？如果是这样，我应该期望什么类型以及如何提取字节数组并从中提取上传的文件信息？

（我使用的是 Chrome - 我知道它在 IE 中不起作用）

任何建议将不胜感激！

Answer 1

想通了。这是 C# 代码：

[HttpPost]
    public virtual string UploadFiles(object obj)
    {
        var length = Request.ContentLength;
        var bytes = new byte[length];
        Request.InputStream.Read(bytes, 0, length);
        // bytes has byte content here. what do do next?

        var fileName = Request.Headers["X-File-Name"];
        var fileSize = Request.Headers["X-File-Size"];
        var fileType = Request.Headers["X-File-Type"];

        var saveToFileLoc = string.Format("{0}\\{1}",
                                       Server.MapPath("/Files"),
                                       fileName);

        // save the file.
        var fileStream = new FileStream(saveToFileLoc, FileMode.Create, FileAccess.ReadWrite);
        fileStream.Write(bytes, 0, length);
        fileStream.Close();

        return string.Format("{0} bytes uploaded", bytes.Length);
    }

这里是 Javascript 代码：

<script type="text/javascript">
(function ()
{
    var filesUpload = document.getElementById("files-upload");
    var dropArea = document.getElementById("drop-area");
    var fileList = document.getElementById("file-list");

    function uploadFile(file)
    {
        var li = document.createElement("li");
        var progressBarContainer = document.createElement("div");
        var progressBar = document.createElement("div");

        progressBarContainer.className = "progress-bar-container";
        progressBar.className = "progress-bar";
        progressBarContainer.appendChild(progressBar);
        li.appendChild(progressBarContainer);

        // Uploading - for Firefox, Google Chrome and Safari
        var xhr = new XMLHttpRequest();

        // Update progress bar
        xhr.upload.addEventListener("progress", function (evt)
        {
            if (evt.lengthComputable)
            {
                progressBar.style.width = (evt.loaded / evt.total) * 100 + "%";
            }
        }, false);

        // File uploaded
        xhr.addEventListener("load", function ()
        {
            progressBarContainer.className += " uploaded";
            progressBar.innerHTML = "Uploaded!";
        }, false);

        xhr.open("post", "/home/UploadFile", true);

        // Set appropriate headers
        xhr.setRequestHeader("Content-Type", "multipart/form-data");
        xhr.setRequestHeader("X-File-Name", file.fileName);
        xhr.setRequestHeader("X-File-Size", file.fileSize);
        xhr.setRequestHeader("X-File-Type", file.type);

        // Send the file
        xhr.send(file);

        // Present file info and append it to the list of files
        var div = document.createElement("div");
        li.appendChild(div);
        var fileInfo = "<div><strong>Name:</strong> " + file.name + "</div>";
        fileInfo += "<div><strong>Size:</strong> " + parseInt(file.size / 1024, 10) + " kb</div>";
        fileInfo += "<div><strong>Type:</strong> " + file.type + "</div>";
        div.innerHTML = fileInfo;

        // insert at beginning of list.
        fileList.insertBefore(li, fileList.firstChild);

        // or insert at end of list.
        //fileList.appendChild(li);
    }

    function traverseFiles(files)
    {
        if (typeof files !== "undefined")
        {
            for (var i = 0, l = files.length; i < l; i++)
            {
                uploadFile(files[i]);
            }
        }
        else
        {
            fileList.innerHTML = "No support for the File API in this web browser";
        }
    }

    filesUpload.addEventListener("change", function ()
    {
        traverseFiles(this.files);
    }, false);

    dropArea.addEventListener("dragleave", function (evt)
    {
        var target = evt.target;

        if (target && target === dropArea)
        {
            this.className = "";
        }
        evt.preventDefault();
        evt.stopPropagation();
    }, false);

    dropArea.addEventListener("dragenter", function (evt)
    {
        this.className = "over";
        evt.preventDefault();
        evt.stopPropagation();
    }, false);

    dropArea.addEventListener("dragover", function (evt)
    {
        evt.preventDefault();
        evt.stopPropagation();
    }, false);

    dropArea.addEventListener("drop", function (evt)
    {
        //document.getElementById("file-list").innerHTML = "";

        traverseFiles(evt.dataTransfer.files);
        this.className = "";
        evt.preventDefault();
        evt.stopPropagation();
    }, false);
})();

Answer 2

这很棒。略有改进：

xhr.setRequestHeader("X-File-Name", file.name);
xhr.setRequestHeader("X-File-Size", file.size);