AjaxUpLoad.js的使用实现无刷新文件上传，如图。

图1 文件上传前

图2 文件上传后

1、创建页面并编写HTML

上传文档:
<div class="uploadFile">
    <span id="doc"><input type="text" disabled="disabled" /></span>
    <input type="hidden" id="hidFileName"  />
    <input type="button" id="btnUploadFile" value="上传" />
    <input type="button" id="btnDeleteFile" value="删除"  />
</div>

上传图片:
<div class="uploadImg">
    <img id="imgShow" src="/images/nophoto.gif" />
    <input type="hidden" id="hidImgName" />
    <input type="button" id="btnUploadImg" value="上传" />
    <input type="button" id="btnDeleteImg" value="删除" />
</div>

<script src="/js/common/AjaxUpload.js" type="text/javascript"></script>

window.onload = function() {
    init();  //初始化
}

//初始化
function init() {
    //初始化文档上传
    var btnFile = document.getElementById("btnUploadFile");
    var doc = document.getElementById("doc");
    var hidFileName = document.getElementById("hidFileName");
    document.getElementById("btnDeleteFile").onclick = function() { DelFile(doc,hidFileName); };
    g_AjxUploadFile(btnFile,hidFileName);
    
    //初始化图片上传
    var btnImg = document.getElementById("btnUploadImg");
    var img = document.getElementById("imgShow");
    var hidImgName = document.getElementById("hidImgName");
    document.getElementById("btnDeleteImg").onclick = function() { DelImg(img,hidImgName); };
    g_AjxUploadImg(btnImg,hidImgName);
}


var g_AjxTempDir = "/file/temp/";
//文档上传
function g_AjxUploadFile(btn,action) {
    var button = btn,interval;
    new AjaxUpload(button,{
    action: ((action == null || action == undefined) ? '/Common/UploadHandler.ashx?fileType=file' : action),data: {},name: 'myfile',onSubmit: function(file,ext) {
            if (!(ext && /^(rar|zip|pdf|pdfx|txt|csv|xls|xlsx|doc|docx|RAR|ZIP|PDF|PDFX|TXT|CSV|XLS|XLSX|DOC|DOCX)$/.test(ext))) {
                alert("您上传的文档格式不对，请重新选择！");
                return false;
            }
        },onComplete: function(file,response) {
            flagValue = response;
            if (flagValue == "1") {
                alert("您上传的文档格式不对，请重新选择！");
            }
            else if (flagValue == "2") {
                alert("您上传的文档大于2M，请重新选择！");
            }
            else if (flagValue == "3") {
                alert("文档上传失败！");
            }
            else {
                hidPut.value = response;
                doc.innerHTML="<a href='" + g_AjxTempDir + response + "' target='_blank'>" + response + "</a>";
            }
        }
    });
}
//图片上传
function g_AjxUploadImg(btn,hidPut) {
    var button = btn,{
        action: '/Common/UploadHandler.ashx?fileType=img',ext) {
            if (!(ext && /^(jpg|JPG|png|PNG|gif|GIF)$/.test(ext))) {
                alert("您上传的图片格式不对，请重新选择！");
                return false;
            }
        },response) {
            flagValue = response;
            if (flagValue == "1") {
                alert("您上传的图片格式不对，请重新选择！");
            }
            else if (flagValue == "2") {
                alert("您上传的图片大于200K，请重新选择！");
            }
            else if (flagValue == "3") {
                alert("图片上传失败！");
            }
            else {
                hidPut.value = response;
                img.src = g_AjxTempDir + response;
            }
        }
    });
}

//删除文档
function DelFile(doc,hidPut) {
    hidPut.value = "";
    doc.innerHTML = "<input type=\"text\" disabled=\"disabled\" />";
}

//删除图片
function DelImg(img,hidPut) {
    hidPut.value = "";
    img.src = "/images/nophoto.gif";
}

4、创建/Common/UploadHandler.ashx处理程序

<%@ WebHandler Language="C#" Class="UploadHandler" %>

using System;
using System.Web;
using System.Text.RegularExpressions;
using System.IO;

public class UploadHandler : IHttpHandler {
    private string _filedir = "";    //文件目录
    /// <summary>
    /// 处理上传文件(1:文件格式不正确、2:文件大小不正确、3:上传失败、文件名称:上传成功)
    /// </summary>
    /// <param name="context"></param>
    public void ProcessRequest (HttpContext context) {
        _filedir = context.Server.MapPath(@"/file/temp/");
        try
        {
            string result = "3";
            string fileType = context.Request.QueryString["fileType"]; //获取上传文件类型
            if (fileType == "file")
            {
                result = UploadFile(context);  //文档上传
            }
            else if (fileType == "img")
            {
                result = UploadImg(context);   //图片上传
            }
            context.Response.Write(result);
        }
        catch
        {
            context.Response.Write("3");//3文件上传失败
        }
    }
    
    /// <summary>
    /// 文档上传
    /// </summary>
    /// <param name="context"></param>
    /// <returns></returns>
    private string UploadFile(HttpContext context)
    {
        int cout = context.Request.Files.Count;
        if (cout > 0)
        {
            HttpPostedFile hpf = context.Request.Files[0];
            if (hpf != null)
            {
                string fileExt = Path.GetExtension(hpf.FileName).ToLower();
                //只能上传文件，过滤不可上传的文件类型  
                string fileFilt = ".rar|.zip|.pdf|.pdfx|.txt|.csv|.xls|.xlsx|.doc|.docx......";
                if (fileFilt.IndexOf(fileExt) <= -1)
                {
                    return "1";
                }
                
                //判断文件大小  
                int length = hpf.ContentLength;
                if (length > 2097152)
                {
                    return "2";
                }  
               
                Random rd = new Random();
                DateTime nowTime = DateTime.Now;
                string newFileName = nowTime.Year.ToString() + nowTime.Month.ToString() + nowTime.Day.ToString() + nowTime.Hour.ToString() + nowTime.Minute.ToString() + nowTime.Second.ToString() + rd.Next(1000,1000000) + Path.GetExtension(hpf.FileName);
                if (!Directory.Exists(_filedir))
                {
                    Directory.CreateDirectory(_filedir);
                }
                string fileName = _filedir + newFileName;
                hpf.SaveAs(fileName);
                return newFileName;
            }

        }
        return "3";
    }

    /// <summary>
    /// 图片上传
    /// </summary>
    /// <param name="context"></param>
    /// <returns></returns>
    private string UploadImg(HttpContext context)
    {
        int cout = context.Request.Files.Count;
        if (cout > 0)
        {
            HttpPostedFile hpf = context.Request.Files[0];
            if (hpf != null)
            {
                string fileExt = Path.GetExtension(hpf.FileName).ToLower();
                //只能上传文件，过滤不可上传的文件类型  
                string fileFilt = ".gif|.jpg|.PHP|.jsp|.jpeg|.png|......";
                if (fileFilt.IndexOf(fileExt) <= -1)
                {
                    return "1";
                }
                
                //判断文件大小  
                int length = hpf.ContentLength;
                if (length > 204800)
                {
                    return "2";
                }
                
                Random rd = new Random();
                DateTime nowTime = DateTime.Now;
                string newFileName = nowTime.Year.ToString() + nowTime.Month.ToString() + nowTime.Day.ToString() + nowTime.Hour.ToString() + nowTime.Minute.ToString() + nowTime.Second.ToString() + rd.Next(1000,1000000) + Path.GetExtension(hpf.FileName);
                if (!Directory.Exists(_filedir))
                {
                    Directory.CreateDirectory(_filedir);
                }
                string fileName = _filedir + newFileName;
                hpf.SaveAs(fileName);
                return newFileName;
            }

        }
        return "3";
    }
    
    #region IHttpHandler 成员

    public bool IsReusable
    {
        get { throw new NotImplementedException(); }
    }

    #endregion
}

/*上传文件*/
.uploadFile{margin-bottom:10px;}
/*上传图片*/
.uploadImg{}
.uploadImg img{width:102px; height:64px; border:1px solid #CCCCCC; display: block;}