最經在工作中要實現檔案的無重新整理上傳，當然XmlHttpRequest物件是無法實現檔案的上傳功能的。google後找到JQuery的fileupload外掛，此外掛通過一個IFrame並在IFrame中建立一個form表單來實現檔案上傳；而在我的應用中還需要帶一些其他的文字引數，而此外掛並未提供此功能。 
        既然是動態建立form表單，那麼更定能加入其他引數的，請看程式碼（注意第41行）： 

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, data)  

    {  

        //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);  

        //增加文字引數的支援  

        if (data) {  

            for (var i in data) {  

                $('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').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, s.data);  

        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;  

    }  

})  

使用方法： 

$.ajaxFileUpload({  

        url: '/ajax/mine/uploadLogo',  

        secureuri:false,  

        fileElementId:'input_logo',  

        dataType: 'json',  

        data: {//加入的文字引數  

            "logoPath": "param1",  

            "logoName": "param2"  

        },  

        success: function(data) {  

        },  

        error: function() {  

            showError("上傳失敗，請檢查檔案是否符合格式要求。");  

        }  

    });