GWT - 在加载文件之前，最简单的加载屏幕的方法 [英] GWT - easiest way to do a simple loading screen until file is loaded
问题描述
当点击一个按钮时，我的GWT应用程序返回嵌入HTML页面中的PDF文件，如下所示：
When clicking a button, my GWT application returns a PDF file embedded in an HTML page which looks something like:
<html><head></head>
<body marginwidth="0" marginheight="0" bgcolor="rgb(38,38,38)">
<embed width="100%" height="100%" name="plugin"
src="http://myserver/?cmd=getMyPdf" type="application/pdf">
</body>
</html>
问题是服务器可能需要一段时间才能创建此PDF文件，所以我想要的是一个带有加载动画的等待屏幕，可以在后台下载PDF文件，然后当文件完成后，如上所述显示页面。
Problem is it can take a while for the server to create this PDF file, so what I want is a waiting screen with a loading animation which can have the PDF file download in the background, and then when the file is done, display the page as described above.
一个明显的方式是显示一个加载页面，向服务器发送一个异步命令，然后一旦调用了onSucceed方法，就像正常调用页面一样。缺点是我必须添加一些服务器端的逻辑，使PDF创建工作在后台...
One obvious way would be to display a loading page, send an asynchronous command to the server and then once the onSucceed method is called, call the page as normal. Downside is I'd have to add some server-side logic for making the PDF creation work in the background...
有没有办法做这个客户端与GWT API？
Is there any way to do this client-side with the GWT API?
推荐答案
你看到这个stackoverflow问题浏览器接收文件下载时检测？基本上给出的答案是您在返回响应中设置一个cookie，并在客户端等待该cookie被设置。这可以很容易地与GWT一起完成，因为它具有一个Scheduler（用于重复定时器检查），并且可以方便地访问Cookies。您仍然需要进行一些服务器更改，但您不必创建后台进程。
Did you see this stackoverflow question Detect when browser receives file download? Basically the answer given is that you set a cookie in the return response and wait on the client side for this cookie to be set. This can be done easily with GWT as it has a Scheduler (for the repeated timer check) and easy access to Cookies. You still need to make some server changes, but you don't have to create a background process.
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