HTML5 文件域+FileReader 分段读取文件并上传到服务器

<div class="container">
    <div class="panel panel-default">
        <div class="panel-heading">分段读取文件：</div>
        <div class="panel-body">
            <input type="file" id="file" />
            <blockquote style="word-break:break-all;"></blockquote>
        </div>
    </div>
</div>

/*
* 分段读取文件为blob ，并使用ajax上传到服务器
* 分段上传exe文件会抛出异常
*/
var fileBox = document.getElementById('file');
file.onchange = function () {
    //获取文件对象
    var file = this.files[0];
    var reader = new FileReader();
    var step = 1024 * 1024;
    var total = file.size;
    var cuLoaded = 0;
    console.info("文件大小：" + file.size);
    var startTime = new Date();
    //读取一段成功
    reader.onload = function (e) {
        //处理读取的结果
        var loaded = e.loaded;
        //将分段数据上传到服务器
        uploadFile(reader.result, cuLoaded, function () {
            console.info('loaded:' + cuLoaded + 'current:' + loaded);
            //如果没有读完，继续
            cuLoaded += loaded;
            if (cuLoaded < total) {
                readBlob(cuLoaded);
            } else {
                console.log('总共用时：' + (new Date().getTime() - startTime.getTime()) / 1000);
                cuLoaded = total;
            }
        });
    }
    //指定开始位置，分块读取文件
    function readBlob(start) {
        //指定开始位置和结束位置读取文件
        //console.info('start:' + start);
        var blob = file.slice(start, start + step);
        reader.readAsArrayBuffer(blob);
    }
    //开始读取
    readBlob(0);
    //关键代码上传到服务器
    function uploadFile(result, startIndex, onSuccess) {
        var blob = new Blob([result]);
        //提交到服务器
        var fd = new FormData();
        fd.append('file', blob);
        fd.append('filename', file.name);
        fd.append('loaded', startIndex);
        var xhr = new XMLHttpRequest();
        xhr.open('post', '../ashx/upload2.ashx', true);
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 && xhr.status == 200) {
                // var data = eval('(' + xhr.responseText + ')');
                console.info(xhr.responseText);
                if (onSuccess)
                    onSuccess();
            }
        }
        //开始发送
        xhr.send(fd);
    }
}

/// <summary>
/// upload2 的摘要说明
/// </summary>
public class upload2 : IHttpHandler
{
    LogHelper.LogHelper _log = new LogHelper.LogHelper();
    int totalCount = 0;
    public void ProcessRequest(HttpContext context)
    {
        HttpContext _Context = context;
        //接收文件
        HttpRequest req = _Context.Request;
        if (req.Files.Count <= 0)
        {
            WriteStr("获取服务器上传文件失败");
            return;
        }
        HttpPostedFile _file = req.Files[0];
        //获取参数
        // string ext = req.Form["extention"];
        string filename = req.Form["filename"];
        //如果是int 类型当文件大的时候会出问题 最大也就是 1.9999999990686774G
        int loaded = Convert.ToInt32(req.Form["loaded"]);
        totalCount += loaded;

        string newname = @"F:\JavaScript_Solution\H5Solition\H5Solition\Content\TempFile\";
        newname += filename;
        //接收二级制数据并保存
        Stream stream = _file.InputStream;
        if (stream.Length <= 0)
            throw new Exception("接收的数据不能为空");
        byte[] dataOne = new byte[stream.Length];
        stream.Read(dataOne, 0, dataOne.Length);
        FileStream fs = new FileStream(newname, FileMode.Append, FileAccess.Write, FileShare.Read, 1024);
        try
        {
            fs.Write(dataOne, 0, dataOne.Length);
        }
        finally
        {
            fs.Close();
            stream.Close();
        }
        _log.WriteLine((totalCount + dataOne.Length).ToString());
        WriteStr("分段数据保存成功");
    }
    private void WriteStr(string str)
    {
        HttpContext.Current.Response.Write(str); 
    }
    public bool IsReusable
    {
        get
        {
            return true;
        }
    }