不是我写的，我看了他的，思路很明确：
实现思路：
在js脚本中动态创建form，动态创建form中的内容，将文件上传的内容以隐藏域的方式提交过去，然后写好回调等。
感觉思路不难，但是我写不出来，感觉需要对于url，http有一定了解，js也ok才可。
代码：
上传的js：
// JavaScript Document jQuery.extend({ createUploadIframe: function(id, uri) { //create frame var frameId = 'jUploadFrame' + id; if(window.ActiveXObject) { //var io = document.createElement('<iframe />'); if(jQuery.browser.version=="9.0" || jQuery.browser.version=="10.0"){ var io = document.createElement('iframe'); io.id = frameId; io.name = frameId; }else if(jQuery.browser.version=="6.0" || jQuery.browser.version=="7.0" || jQuery.browser.version=="8.0"){ var io = document.createElement('<iframe >); 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 = jQuery('<form action="" method="POST" name="' + formId + '" >); var oldElement = jQuery('#' + fileElementId); var newElement = jQuery(oldElement).clone(); jQuery(oldElement).attr('id', fileId); jQuery(oldElement).before(newElement); jQuery(oldElement).appendTo(form); //add data if(data) { for (var i in data) { $('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(form); } } //set attributes jQuery(form).css('position', 'absolute'); jQuery(form).css('top', '-1200px'); jQuery(form).css('left', '-1200px'); jQuery(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 = s.id; //var id = s.fileElementId; var form = jQuery.createUploadForm(id, s.fileElementId,s.data); var io = jQuery.createUploadIframe(id, s.secureuri); var frameId = 'jUploadFrame' + id; var formId = 'jUploadForm' + id; if( s.global && ! jQuery.active++ ){ // Watch for a new set of requests jQuery.event.trigger( "ajaxStart" ); } var requestDone = false; // Create the request object var xml = {}; if( s.global ){ jQuery.event.trigger("ajaxSend", [xml, s]); } var uploadCallback = function(isTimeout){ // Wait for a response to come back 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( s.success ){ // ifa local callback was specified, fire it and pass it the data s.success( data, status ); }; if( s.global ){ // Fire the global callback jQuery.event.trigger( "ajaxSuccess", [xml, s] ); }; } else{ jQuery.handleError(s, xml, status); } } catch(e){ status = "error"; jQuery.handleError(s, xml, status, e); }; if( s.global ){ // The request was completed jQuery.event.trigger( "ajaxComplete", [xml, s] ); }; // Handle the global AJAX counter if(s.global && ! --jQuery.active){ jQuery.event.trigger("ajaxStop"); }; if(s.complete){ s.complete(xml, status); }; jQuery(io).unbind(); setTimeout(function(){ try{ jQuery(io).remove(); jQuery(form).remove(); }catch(e){ jQuery.handleError(s, xml, null, e); }}, 100); xml = null; }; } // Timeout checker if( s.timeout > 0 ){ setTimeout(function(){if(!requestDone ){uploadCallback( "timeout" );}}, s.timeout); } try{ var form = jQuery('#' + formId); jQuery(form).attr('action', s.url); jQuery(form).attr('method', 'POST'); jQuery(form).attr('target', frameId); if(form.encoding){ form.encoding = 'multipart/form-data'; }else{ form.enctype = 'multipart/form-data'; } jQuery(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); } */ jQuery('#' + frameId).load(uploadCallback); return {abort: function () {}}; }, uploadHttpData: function( r, type ) { var data = !type; data = type == "xml" || data ? r.responseXML : r.responseText; // ifthe type is "script", eval it in global context if( type == "script" ){ jQuery.globalEval( data ); } // Get the JavaScript object, ifJSON is used. if( type == "json" ){ data = r.responseText; var start = data.indexOf(">"); if(start != -1) { var end = data.indexOf("<", start + 1); if(end != -1) { data = data.substring(start + 1, end); } } eval( "data = " + data); } // evaluate scripts within html if( type == "html" ){ jQuery("<div>").html(data).evalScripts(); } return data; }, /*handleError: function( s, xml, status, e ) { // If a local callback was specified, fire it if ( s.error ) s.error( xml, status, e ); // Fire the global callback if ( s.global ) jQuery.event.trigger( "ajaxError", [xml, s, e] ); }*/ handleError: function( s, xhr, status, e ) { // If a local callback was specified, fire it if ( s.error ) { s.error.call( s.context || s, xhr, status, e ); } // Fire the global callback if ( s.global ) { (s.context ? jQuery(s.context) : jQuery.event).trigger("ajaxError", [xhr, s, e] ); } } });