最近在做一个项目需要实现异步上传图片，在网上找了很多资料后，采用了ajaxfileupload可以实现，以下是核心代码：

jsp:

<!-- 上传窗口 --> <div id="uploadPicWindow" class="easyui-window" title="上传图片" style="width:420px;height:220px;padding:20px;background:#fafafa;" data-options="iconCls:'icon-save',closable:true, collapsible:true,minimizable:true,maximizable:true"><form id="picForm" action="" method="post"><div style="margin-bottom:20px">图片名称:<input type="text" name="name" id="picName" class="easyui-textbox" style="width:80%" data-options="required:true,validType:'stringCheck'"/></div><br/><div style="margin-bottom:20px">选择图片:<input type="file" name="file" id="file" data-options="prompt:'Choose a file...'" style="width:80%"/></div><div id="picTip"></div><div id="formWindowfooterPic1" style="padding:5px;text-align:right;"> <a href="#" οnclick="submitPic();" class="easyui-linkbutton" data-options="iconCls:'icon-save'">提交</a></div></form></div>

js:

//新建或编辑 保存提交 function submitPic(){if(!$("#picForm").form('validate')){return false;}var projectId = $("#projectId").val();var name=$("#picName").val();var type="1";//展示图片var f = $("#file").val();if(f==null||f==""){$("#picTip").html("<span style='color:Red'>错误提示:上传文件不能为空,请重新选择文件</span>");return false;}else{var extname = f.substring(f.lastIndexOf(".")+1,f.length);extname = extname.toLowerCase();//处理了大小写if(extname!= "jpeg"&&extname!= "jpg"&&extname!= "gif"&&extname!= "png"){$("#picTip").html("<span style='color:Red'>错误提示:格式不正确,支持的图片格式为：JPEG、GIF、PNG！</span>");return false;}}var file = document.getElementById("file").files; var size = file[0].size;if(size>2097152){$("#picTip").html("<span style='color:Red'>错误提示:所选择的图片太大，图片大小最多支持2M!</span>"); return false;}ajaxFileUploadPic(projectId,name,type); }function ajaxFileUploadPic(projectId,name,type) {$.ajaxFileUpload({url : '${ctx}/projectPic/saveorupdate.jhtml?projectId='+projectId+'&name='+name+'&type='+type, //用于文件上传的服务器端请求地址secureuri : false, //一般设置为falsefileElementId : 'file', //文件上传空间的id属性 <input type="file" id="file" name="file" />type : 'post',dataType : 'json', //返回值类型 一般设置为jsonsuccess : function(data, status) //服务器成功响应处理函数{$("#picList").datagrid('reload');$('#uploadPicWindow').window('close');// alert(data.msg);},error : function(data, status, e)//服务器响应失败处理函数{$("#picList").datagrid('reload');$('#uploadPicWindow').window('close');// alert(data.msg);}});return false; }

ajaxfileupload.js jQuery.extend({createUploadIframe: function(id, uri){//create framevar frameId = 'jUploadFrame' + id;var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" style="position:absolute; top:-9999px; left:-9999px"';if(window.ActiveXObject){if(typeof uri== 'boolean'){iframeHtml += ' src="' + 'javascript:false' + '"';}else if(typeof uri== 'string'){iframeHtml += ' src="' + uri + '"';} }iframeHtml += ' />';jQuery(iframeHtml).appendTo(document.body);return jQuery('#' + frameId).get(0); },createUploadForm: function(id, fileElementId, data){//create form var formId = 'jUploadForm' + id;var fileId = 'jUploadFile' + id;var form = jQuery('<form action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>'); if(data){for(var i in data){jQuery('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(form);} } var oldElement = jQuery('#' + fileElementId);var newElement = jQuery(oldElement).clone();jQuery(oldElement).attr('id', fileId);jQuery(oldElement).before(newElement);jQuery(oldElement).appendTo(form);//set attributesjQuery(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 = new Date().getTime() var form = jQuery.createUploadForm(id, s.fileElementId, (typeof(s.data)=='undefined'?false:s.data));var io = jQuery.createUploadIframe(id, s.secureuri);var frameId = 'jUploadFrame' + id;var formId = 'jUploadForm' + id; // Watch for a new set of requestsif ( s.global && ! jQuery.active++ ){jQuery.event.trigger( "ajaxStart" );} var requestDone = false;// Create the request objectvar xml = {} if ( s.global )jQuery.event.trigger("ajaxSend", [xml, s]);// Wait for a response to come backvar 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 notmodifiedif ( 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 dataif ( s.success )s.success( data, status );// Fire the global callbackif( s.global )jQuery.event.trigger( "ajaxSuccess", [xml, s] );} elsejQuery.handleError(s, xml, status);} catch(e) {status = "error";jQuery.handleError(s, xml, status, e);}// The request was completedif( s.global )jQuery.event.trigger( "ajaxComplete", [xml, s] );// Handle the global AJAX counterif ( s.global && ! --jQuery.active )jQuery.event.trigger( "ajaxStop" );// Process resultif ( 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 checkerif ( s.timeout > 0 ) {setTimeout(function(){// Check to see if the request is still happeningif( !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){jQuery(form).attr('encoding', 'multipart/form-data'); }else{ jQuery(form).attr('enctype', 'multipart/form-data'); } jQuery(form).submit();} catch(e) { jQuery.handleError(s, xml, null, e);}jQuery('#' + frameId).load(uploadCallback );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 contextif ( type == "script" )jQuery.globalEval( data );// Get the JavaScript object, if JSON is used.if ( type == "json" )eval( "data = " + data );// evaluate scripts within htmlif ( type == "html" )jQuery("<div>").html(data).evalScripts();return data;},handleError: function( s, xhr, status, e ) {// If a local callback was specified, fire itif ( s.error ) {s.error.call( s.context || s, xhr, status, e );}// Fire the global callbackif ( s.global ) {(s.context ? jQuery(s.context) : jQuery.event).trigger( "ajaxError", [xhr, s, e] );}}})

注：如果出现

jQuery.handleError is not a function  原因是，经测试handlerError只在jquery-1.4.2之前的版本中存在，jquery-1.6 和1.7中都没有这个函数了，因此在1.4.2中将这个函数复制到了ajaxFileUpload.js中，问题解决 handleError: function( s, xhr, status, e ) { // If a local callback was specified, fire itif ( s.error ) {s.error.call( s.context || s, xhr, status, e );}// Fire the global callbackif ( s.global ) {(s.context ? jQuery(s.context) : jQuery.event).trigger( "ajaxError", [xhr, s, e] );}}, 问题2：一直得到error ，无法执行指定的success方法。通过追踪ajaxFileUpload的执行过程发现，在调用它自身的uploadHttpData函数时，当执行if（type=="json") eval("data = "+data); 会抛出异常，导致在处理异常的时候将status = "error" 因此一直执行error方法。 上网查询，得知eval函数是用来执行一段js代码，而并不是如我所想的反解json串 eval("data = "+data);的意思是 将data 赋值给 data参数 ，但是当我返回给页面的是一个简单的字符串，比如"OK" ，时，这样写就抛出异常。最后改为 eval("data = \" "+data+" \" ");即将返回的数据用双引号引起来当作字符串，然后赋给 data 。终于成功了。。。

action:

@RequestMapping(value = "/saveorupdate.jhtml")@ResponseBodypublic synchronized String saveOrUpdate(HttpServletRequest request) throws IOException {DynamicParams params = new DynamicParams(request);String projectId = request.getParameter("projectId");String name = request.getParameter("name");String type = request.getParameter("type");params.put("projectId", projectId);params.put("name", name);params.put("type", type);MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;MultipartFile file = null;if("1".equals(type)){file = multipartRequest.getFile("file");// 获取上传文件名}else{file = multipartRequest.getFile("attachFile");// 获取上传文件名}ProjectPic projectPic = params.convertToEntity(ProjectPic.class); projectPicManager.save(projectPic, file.getInputStream());return successMsg();}
到此一切ok，开始上传文件吧！

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