Jq_input file标签上传图片到服务器

引入jQuery库
引入ajaxfileupload.js上传插件库(这也是jQuery的一个插件)
以ASP.NET为例

<input type="file" id="uploadfile" name="uploadfile"/>
<script type="text/javascript">
$("#uploadfile").change(function(){
    
$.ajaxFileUpload({
        url: '../ajax/AjaxCallback.ashx',//处理上传用的后台程序,可以是PHP,也可以是ASP等
        secureuri: false,//异步
        fileElementId: 'uploadfile',//上传控件ID
        dataType: 'json',//返回的数据信息格式
        success: function(data, status) {
            if (data.code == '10000') {
             alert("上传成功");

} else {
                alert("上传失败");
            }
        }, error: function(data, status, e) {
           alert(e);
        }
    })

});

</script>
后台CS代码

/// <summary>
    /// 图片上传
    /// </summary>
    private void ImageUpload()
    {
        Response.ContentType = "text/html";//这里一定要html
        if (Request.Files.Count > 0)
        {
            HttpPostedFile file = Request.Files[0];
            if (file.ContentLength > 0)
            {
                string suffix = file.FileName.Substring(file.FileName.LastIndexOf('.'));//后缀
                if (".jpg.png.gif.jpeg".IndexOf(suffix.ToLower()) == -1)//文件格式,这里采用图片格式说明
                {
                    Response.Write("{"msg":"文件格式不正确!",code:"10001"}");
                    return;
                }                

                try
                {
                    file.SaveAs(Server.MapPath("~/uploadfile/") + newName);
                    Response.Write("{"msg":"" + newName + "",code:"10000"}");
                    return;
                }
                catch (Exception ex)
                {
                    Response.Write("{"msg":"" + HttpUtility.HtmlEncode(ex.Message) + "",code:"10001"}");
                    return;
                }
            }
            Response.Write("{"msg":"请选择要上传的文件!",code:"10001"}");
            return;
        }
        Response.Write("{"msg":"请选择要上传的文件!",code:"10001"}");
        return;
    }
http://www.cnblogs.com/linjiqin/p/3530848.html
http://www.cnblogs.com/kissdodog/archive/2012/12/15/2819025.html
http://www.phpletter.com/cn/Demo/AjaxFileUpload-Demo/