ajax 分布式跨域怎么实现图片上传！急急。。。

插件
--ajaxfileupload.js
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;
}
})

---页面代码

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="ajaxfileupload.js"></script>
<script type="text/javascript">
function ajaxFileUpload()
{

$("#loading")
.ajaxStart(function(){
$(this).show();
})//开始上传文件时显示一个图片
.ajaxComplete(function(){
$(this).hide();
});//文件上传完成将图片隐藏起来

$.ajaxFileUpload
(
{
url:'../gap/fileUpload.do',//用于文件上传的服务器端请求地址
secureuri:false,//一般设置为false
fileElementId:'file',//文件上传空间的id属性 <input type="file" id="file" name="file" />
dataType: 'json',//返回值类型 一般设置为json
success: function (data, status) //服务器成功响应处理函数
{
alert(data.message);//从服务器返回的json中取出message中的数据,其中message为在struts2中action中定义的成员变量

if(typeof(data.error) != 'undefined')
{
if(data.error != '')
{
alert(data.error);
}else
{
alert(data.message);
}
}
},
error: function (data, status, e)//服务器响应失败处理函数
{
alert(e);
}
}
)

return false;

}
</script>
</head>
<body>
<img src="loading.gif" id="loading" style="display: none;">
<input type="file" id="file" name="file" />
<br />
<input type="button" value="上传" onclick="return ajaxFileUpload();">
</body>
</html>



action 类方法！


@SuppressWarnings("deprecation")
public String fileUpload() throws Exception {

String path = ServletActionContext.getRequest().getRealPath("/upload1");

try {
File f = this.getFile();
if(this.getFileFileName().endsWith(".exe")){
message="对不起,你上传的文件格式不允许!!!";
return ERROR;
}
FileInputStream inputStream = new FileInputStream(f);
FileOutputStream outputStream = new FileOutputStream(path + "/"+ this.getFileFileName());
byte[] buf = new byte[1024];
int length = 0;
while ((length = inputStream.read(buf)) != -1) {
outputStream.write(buf, 0, length);
}
inputStream.close();
outputStream.flush();
} catch (Exception e) {
e.printStackTrace();
message = "对不起,文件上传失败了!!!!";

}
return SUCCESS;
}


}