SWFUpload在火狐下的session问题

 var swfu;

	window.onload = function() {

		var settings = {

			upload_url :_context+"/ads/uploadImg;jsessionid="+sessionId,

			//post_params: {"JSESSIONID" :sessionId},

	   		file_post_name:"filedata", 

	   		// File Upload Settings

	   		file_size_limit : "20MB", // 20MB

	   		file_types : "*.jpg;*.gif;*.png",//设置可上传的类型

	   		file_types_description : "所有文件",

	   		file_upload_limit : "0", //最大可以上传文件数量 0为不限制

	   		file_queue_limit : 0,

	   		prevent_swf_caching : true,//在相关的swf文件增加随机参数以避免Flash被缓存（建议打开，Flash被缓存已经导致太多问题了）

	   		custom_settings : {

				progressTarget : "fsUploadProgress",

				cancelButtonId : "btnCancel"

			},

			// Button settings

			button_image_url: "../../js/lib/SWFUpload2.2/swfupload/images/TestImageNoText_65x29.png",

			button_width: "65",

			button_height: "29",

			button_placeholder_id: "spanButtonPlaceHolder",

			button_text: '<span class="theFont">浏览</span>',

			button_text_style: ".theFont { font-size: 16; }",

			button_text_left_padding: 12,

			button_text_top_padding: 3,

			

			file_queued_handler : fileQueued,

			file_queue_error_handler : fileQueueError,

			file_dialog_complete_handler : fileDialogComplete,

			upload_start_handler : uploadStart,

			upload_progress_handler : uploadProgress,

			upload_error_handler : uploadError,

			upload_success_handler : uploadSuccess,

			upload_complete_handler : uploadComplete,

			queue_complete_handler : queueComplete,	

			flash_url : "../../js/lib/SWFUpload2.2/swfupload/swfupload.swf",

	   		debug: true

		};



		swfu = new SWFUpload(settings);

     };