js异步上传图片

通过iframe来实现无刷新的的文件上传，其实是有刷新的，只是在iframe里面隐藏了而已

 

简单的原理说明：

<form id="form1" method="post" action="upload.do" enctype="multipart/form-data"  target="uploadframe" >
<input type="file" id="upload" name="文件上传" />
</form>

<iframe id="uploadframe" name="result_frame"   style="visibility:hidden;"></iframe>

 

form里面的target要与iframe里面的id的值相等，指示是form相应了post事件，也就是post时间相应的时候刷新的是iframe而不是整个页面。

 

二、

利用jQuery的插件AjaxFileUpload 可以简单地实现这个异步的上传的效果      插件地址： http://www.phpletter.com/Our-Projects/AjaxFileUpload/

 

 <script type="text/javascript" language="javascript" src="js/jquery.js"></script>

 <script type="text/javascript" language="javascript" src="js/ajaxfileupload.js"></script>

 

    function ajaxFileUpload()    {        $("#loading")        .ajaxStart(function(){            $(this).show();                    })        .ajaxComplete(function(){            $(this).hide();                    });        $.ajaxFileUpload        (            {                url:'Upload.ashx',                secureuri:false,                fileElementId:'fileToUpload',                dataType: 'json',                success: function (data, status)                {                                    if(typeof(data.error) != 'undefined')                    {                        if(data.error != '')                        {                            alert(data.error);                        }else                        {                            alert(data.msg);                        }                    }                },                error: function (data, status, e)                {                    alert(e);                }            }        )                return false;    }

 

 

<input id="fileToUpload" type="file" size="45" name="fileToUpload">

<input type="button" id="buttonUpload" onclick="return ajaxFileUpload();">
       上传</input>

 

 

Upload.ashx

 

if (Request.Files.Count > 0)   {    HttpPostedFile file = Request.Files[0];    string msg = "";    string error = "";    if (file.ContentLength == 0)     error = "文件长度为0";    else    {     file.SaveAs(Server.MapPath("file") + "\\" + Path.GetFileName(file.FileName));     msg = "上传成功";    }    string result = "{ error:'" + error + "', msg:'" + msg + "'}";    Response.Write(result);    Response.End();   }

 

 

 

 

PS:ajaxfileupload.js代码

 

jQuery.extend({    createUploadIframe: function(id, uri)    {            //create frame            var frameId = 'jUploadFrame' + id;                        if(window.ActiveXObject) {                var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');                if(typeof uri== 'boolean'){                    io.src = 'javascript:false';                }                else if(typeof uri== 'string'){                    io.src = uri;                }            }            else {                var io = document.createElement('iframe');                io.id = frameId;                io.name = frameId;            }            io.style.position = 'absolute';            io.style.top = '-1000px';            io.style.left = '-1000px';            document.body.appendChild(io);            return io                },    createUploadForm: function(id, fileElementId)    {        //create form            var formId = 'jUploadForm' + id;        var fileId = 'jUploadFile' + id;        var form = $('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');            var oldElement = $('#' + fileElementId);        var newElement = $(oldElement).clone();        $(oldElement).attr('id', fileId);        $(oldElement).before(newElement);        $(oldElement).appendTo(form);        //set attributes        $(form).css('position', 'absolute');        $(form).css('top', '-1200px');        $(form).css('left', '-1200px');        $(form).appendTo('body');                return form;    },    ajaxFileUpload: function(s) {        // TODO introduce global settings, allowing the client to modify them for all requests, not only timeout                s = jQuery.extend({}, jQuery.ajaxSettings, s);        var id = new Date().getTime()                var form = jQuery.createUploadForm(id, s.fileElementId);        var io = jQuery.createUploadIframe(id, s.secureuri);        var frameId = 'jUploadFrame' + id;        var formId = 'jUploadForm' + id;                // Watch for a new set of requests        if ( s.global && ! jQuery.active++ )        {            jQuery.event.trigger( "ajaxStart" );        }                    var requestDone = false;        // Create the request object        var xml = {}           if ( s.global )            jQuery.event.trigger("ajaxSend", [xml, s]);        // Wait for a response to come back        var uploadCallback = function(isTimeout)        {                        var io = document.getElementById(frameId);            try             {                                if(io.contentWindow)                {                     xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;                     xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;                                     }else if(io.contentDocument)                {                     xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;                    xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;                }                                    }catch(e)            {                jQuery.handleError(s, xml, null, e);            }            if ( xml || isTimeout == "timeout")             {                                requestDone = true;                var status;                try {                    status = isTimeout != "timeout" ? "success" : "error";                                        // Make sure that the request was successful or notmodified                    if ( status != "error" )                    {                        // process the data (runs the xml through httpData regardless of callback)                        var data = jQuery.uploadHttpData( xml, s.dataType );                            // If a local callback was specified, fire it and pass it the data                        if ( s.success )                            s.success( data, status );                            // Fire the global callback                        if( s.global )                            jQuery.event.trigger( "ajaxSuccess", [xml, s] );                    } else                        jQuery.handleError(s, xml, status);                } catch(e)                 {                    status = "error";                    jQuery.handleError(s, xml, status, e);                }                // The request was completed                if( s.global )                    jQuery.event.trigger( "ajaxComplete", [xml, s] );                // Handle the global AJAX counter                if ( s.global && ! --jQuery.active )                    jQuery.event.trigger( "ajaxStop" );                // Process result                if ( s.complete )                    s.complete(xml, status);                jQuery(io).unbind()                setTimeout(function()                                    {    try                                         {                                            $(io).remove();                                            $(form).remove();                                                                                        } catch(e)                                         {                                            jQuery.handleError(s, xml, null, e);                                        }                                                                        }, 100)                xml = null            }        }        // Timeout checker        if ( s.timeout > 0 )         {            setTimeout(function(){                // Check to see if the request is still happening                if( !requestDone ) uploadCallback( "timeout" );            }, s.timeout);        }        try         {           // var io = $('#' + frameId);            var form = $('#' + formId);            $(form).attr('action', s.url);            $(form).attr('method', 'POST');            $(form).attr('target', frameId);            if(form.encoding)            {                form.encoding = 'multipart/form-data';                            }            else            {                                form.enctype = 'multipart/form-data';            }                        $(form).submit();        } catch(e)         {                        jQuery.handleError(s, xml, null, e);        }        if(window.attachEvent){            document.getElementById(frameId).attachEvent('onload', uploadCallback);        }        else{            document.getElementById(frameId).addEventListener('load', uploadCallback, false);        }                 return {abort: function () {}};        },    uploadHttpData: function( r, type ) {        var data = !type;        data = type == "xml" || data ? r.responseXML : r.responseText;        // If the type is "script", eval it in global context        if ( type == "script" )            jQuery.globalEval( data );        // Get the JavaScript object, if JSON is used.        if ( type == "json" )            eval( "data = " + data );        // evaluate scripts within html        if ( type == "html" )            jQuery("<div>").html(data).evalScripts();            //alert($('param', data).each(function(){alert($(this).attr('value'));}));        return data;    }})

 

 三、纯iframe实现上传

upload.ashx

 

//<%@ WebHandler Language="C#" Class="upload" %>using System;using System.Web;public class upload : IHttpHandler {    private string Js(string v) {//此函数进行js的转义替换的，防止字符串中输入了'后造成回调输出的js中字符串不闭合        if (v == null) return "";        return v.Replace("'", @"\'");    }    //下面就是一个简单的示例，保存上传的文件，如果要验证上传的后缀名，得自己写，还有写数据库什么的    public void ProcessRequest (HttpContext context) {        HttpRequest Request = context.Request;        HttpResponse Response = context.Response;        HttpServerUtility Server = context.Server;        //指定输出头和编码        Response.ContentType = "text/html";        Response.Charset = "utf-8";                HttpPostedFile f = Request.Files["upfile"];//获取上传的文件        string des = Request.Form["des"]//获取描述            ,newFileName=Guid.NewGuid().ToString();//使用guid生成新文件名        if (f.FileName == "")//未上传文件            Response.Write("<script>parent.UpdateMsg('','');</script>");//输出js，使用parent对象得到父页的引用        else { //保存文件            newFileName += System.IO.Path.GetExtension(f.FileName);//注意加上扩展名            try {                f.SaveAs(Server.MapPath("~/uploads/" + newFileName));//如果要保存到其他地方，注意修改这里                //调用父过程更新内容，注意要对des变量进行js转义替换，防止字符串不闭合提示错误                Response.Write("<script>parent.UpdateMsg('" +Js(des)+ "','" + newFileName + "')</script>");            }            catch {                Response.Write("<script>alert('保存文件失败！\\n请检查文件夹是否有写入权限！');</script>");//如果保存失败，输出js提示保存失败            }                    }    }     public bool IsReusable {        get {            return false;        }    }}

 

 

test.htm

<!!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">><html xmlns="http://www.w3.org/1999/xhtml"><head>    <meta http-equiv="content-type" content="text/html;charset=utf-8" />    <title>使用隐藏的Iframe实现ajax无刷新上传</title></head><body>    <script type="text/javascript">    function UpdateMsg(des,filename){//此函数用来提供给提交到的页面如upload.ashx输出js的回调，更新当前页面的信息      if(filename==''){alert('未上传文件！');return false;}      document.getElementById('ajaxMsg').innerHTML='你在表单中输入的“文件描述”为：'+des+'<br/>'      +'上传的图片为：<a href="uploads/'+filename+'" target="_blank">'+filename+'</a>';    }        function check(f){      if(f.des.value==''){         alert('请输入文件描述！');f.des.focus();return false;      }      if(f.upfile.value==''){        alert('请选择文件！');f.upfile.focus();return false;      }    }    </script>     <!--隐藏的iframe来接受表单提交的信息-->    <iframe name="ajaxifr" style="display:none;"></iframe>    <!--这里设置target="ajaxifr"，这样表单就提交到iframe里面了，和平时未设置target属性时默认提交到当前页面-->    <!--注意一点的是使用iframe时在提交到的页面可以直接输出js来操作父页面的信息，一般的ajax提交文本信息时你需要返回信息，如果是js信息你还得eval下-->    <form method="post" enctype="multipart/form-data" action="upload.ashx" target="ajaxifr" onsubmit="return check(this)">    文件描述：<input type="text" name="des" /><br >    选择文件：<input type="file" name="upfile" /><br >    <input type="submit" value="提交" />    </form>    <!--放入此div用来实现上传的结果-->    <div id="ajaxMsg"></div></body></html>