原理: Flex(尤指AIR环境), 使用URLLoader发送POST请求, 将要预览的HTML代码发送到服务器端Servlet, 服务器端收到请求后创建临时文件, 将HTML存到临时文件中. Flex端收到URLLoader Complete事件后, 使用navigateToURL navigate到Servlet上(使用GET), Servelet 返回文件内容 —- 在上述过程中, Flex端生成UUID作为代码读写的key.

Flex端代码:

	protected var uuidPriview:String;
	/**
	 * 在浏览器中预览邮件, 解决方法: 生成uuid, 连同邮件内容发送到服务器端, 服务器端创建文件, 完毕后携带uuid Navigat到服务器端, 服务器端返回邮件内容, 实现预览.
	 * 在AIR中, 会将POST视为GET:
	 * in Adobe AIR, when using the navigateToURL() function, the runtime treats a URLRequest that uses the POST method (one that has its method property set to URLRequestMethod.POST) as using the GET method.
	 * @see http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/package.html#navigateToURL()
	 **/
	protected function priviewInBroswer():void {
		var urlReq:URLRequest = new URLRequest(PRIVIEW_URL);
		urlReq.method = URLRequestMethod.POST;
		var data:URLVariables = new URLVariables;
		data.content = "html codes...."; // 放入要预览的代码
		data.uuid = uuidPriview = UIDUtil.createUID(); // 生成UUID, 作为Java端文件名.
		urlReq.data = data;

		var urlLoader:URLLoader = new URLLoader();
		urlLoader.addEventListener(Event.COMPLETE, onPriviewSendSuccess);
		urlLoader.load(urlReq);
	}

	/** 预览请求发送结束后响应. */
	protected function onPriviewSendSuccess(e:Event):void {
		var urlReq:URLRequest = new URLRequest(PRIVIEW_URL);
		var data:URLVariables = new URLVariables;
		data.uuid = uuidPriview; // Get中携带uuid.
		urlReq.data = data;
		navigateToURL(urlReq); // 打开浏览器
	}

Java端代码:

	/**
	 * 接收到Get请求后, 读取uuid, 读取uuid对应文件的内容, 写到response中, 客户端实现预览.
	 */
	public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String uuid = req.getParameter("uuid");
		String content = FileUtil.getStringFromFile("E:\\temp\\priview\\" + uuid); // 读取内容

		resp.getWriter().write(content);
	}

	@Override
	/**
	 * 接受请求, 创建文件, 文件名称为创建的uuid.
	 */
	public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String content = req.getParameter("content");
		String uuid = req.getParameter("uuid");

		String filePath = "E:\\temp\\priview\\" + uuid;
		File pf = new File(filePath);
		pf.createNewFile();
		FileUtil.saveStringToFile(content, pf, "utf-8"); // 创建并写入文件

		resp.getWriter().write("get it");
	}

----------Post from: @LiGuoliang.com, 欢迎回来~----------

var fileRef:FileReference = new FileReference();
		var request:URLRequest = new URLRequest(serviceUrl);

		request.method = URLRequestMethod.POST;
		var encoder : Base64Encoder = new Base64Encoder();
		encoder.encode(userName + ":" + password);
		request.requestHeaders.push(new URLRequestHeader("Authorization", "Basic " + encoder.toString())); // ** 增加认证信息

		fileRef.addEventListener(Event.OPEN, onFileDownloadBegin);
		fileRef.addEventListener(Event.COMPLETE, onFileDownloadComplete);
		fileRef.addEventListener(IOErrorEvent.IO_ERROR, onFileDownloadError);
		fileRef.addEventListener(Event.CANCEL, onFileDownLoadCancel);
		fileRef.download(request, getExportFileName(serviceUrl));

----------Post from: @LiGuoliang.com, 欢迎回来~----------

// 下载文件
	protected function downloadTemplateFile():void {
		var fileRef:FileReference = new FileReference();
		var urlReq:URLRequest = new URLRequest(_pathTemplateFile);
		fileRef.addEventListener(Event.OPEN,onDownloadBegin);
		fileRef.addEventListener(Event.COMPLETE, onDownloadComplete);
		fileRef.addEventListener(Event.CANCEL, onDownloadCancel);
		fileRef.addEventListener(IOErrorEvent.IO_ERROR, onDownloadError);
		fileRef.download(urlReq);
	}

	// 模板文件下载开始时响应.
	protected function onDownloadBegin(e:Event):void {
		appendTextToOutPut(RM.getString(BUNDLE_ASMT_MGT, "template.download.begin"));
	}

	// 当下载结束后响应. */
	protected function onDownloadComplete(e:Event):void {
		var file:FileReference = e.target as FileReference;
		appendTextToOutPut(RM.getString(BUNDLE_ASMT_MGT, "template.download.success", [file.name, FileUtils.formatFileSize(file.size)]));
		log.info("模板文件下载结束: " + file.name + "-" + file.size);
	}

	// 当下载取消时响应. */
	protected function onDownloadCancel(e:Event):void {
		appendTextToOutPut(RM.getString(BUNDLE_ASMT_MGT, "controller.download.canceled"));
	}

	// 当下载出现错误时响应. */
	protected function onDownloadError(e:IOError):void {
		appendTextToOutPut(RM.getString(BUNDLE_ASMT_MGT, "template.download.error", [e.message]));
		log.error("下载出错" + e.message);
	}

----------Post from: @LiGuoliang.com, 欢迎回来~----------