一、创建input元素
<input type="file" id="fileToUpload" name="fileToUpload" value="浏览"/>
二、导入jquery.js和ajaxfileupload.js文件
jQuery.extend({
createUploadIframe: function(id, uri)
{
//create frame
var 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 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 = 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 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
{
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(){
// Check to see if the request is still happening
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)
{
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 context
if ( type == "script" )
jQuery.globalEval( data );
// Get the JavaScript object, if JSON is used.
if ( type == "json" ) {
if(data.indexOf('<pre') != -1) {
//此段代码时为了兼容火狐和chrome浏览器
var newDiv = jQuery(document.createElement("div"));
newDiv.html(data);
data = $("pre:first", newDiv).html();
}
eval( "data = " + data );
}
// evaluate scripts within html
if ( type == "html" )
jQuery("<div>").html(data).evalScripts();
return data;
}
});
注意：在ajaxfileupload中会用到jquery的handleError函数，但是此函数在1.4.2之后不存在了，所有如果用到更高的
版本需要复制进去
三、写调用代码
function uploadImage() {
$.ajaxFileUpload({
url: 'photo/upload',//需要链接到服务器地址
secureuri:false,
fileElementId: 'fileToUpload',//文件选择框的id属性
dataType:'json',//服务器返回的格式，可以是json
success: function (data){
if (data['result'] == 1) {
}
},
error: function(data){
}
});
}
四、写后台处理代码：
List items = super.getUploadFileItems(req);//使用fileupolad组件获取request中的参数
HashMap<String, String> params = super.getUploadParams(items);
Iterator iter = items.iterator();
FileItem fileItem = null;
while (iter.hasNext()) {
FileItem item = (FileItem) iter.next();
if (!item.isFormField()) {
fileItem = item;
break;
}
}
byte[] imageContent = null;
String suffix = null;
if (fileItem != null) {
imageContent = IOTools.readContent(
fileItem.getInputStream(), 4096);
suffix = fileItem.getContentType();
}
注意：
（1）如果服务端想返回json格式，一定不能加上response.setContentType("application/json");
否则IE和opera会解析成文件下载，或者写成response.setContentType("text/html");
结合strut2是result节点中也要设置contentType，否则浏览器总是提示将返回的JSON结果另存为文件，不会交给ajaxfileupload处理。
这是因为struts2 JSON Plugin默认的contentType为application/json，而ajaxfileupload则要求为text/html。
（2）返回url赋值给img的src时，记得加上时间戳或者保证url不重复，否则会被浏览器缓存，导致无法实时看到图片