Vaadin 7 - 即时下载动态创建的文件 [英] Vaadin 7 - instant download of dynamically created file

问题描述

我的场景是:使用 Vaadin 7.7.10，我点击生成的文件，我想在生成后下载.

My scenario is: using Vaadin 7.7.10, I have on click generated file, that I want to download once it is generated.

我有生成器方法，它返回byte[](如果需要，也可以很容易地修改为任何OutputStream)，然后我创建StreamResource> 从它.所以我已经准备好下载资源了，但现在怎么办?

I have generator method, that returns byte[] (could be also easily modified to any OutputStream if needed), then I create StreamResource from it. So I have the resource ready to be downloaded, but now what?

我相信不能使用 FileDownloader 的方法，因为在实际单击扩展按钮之前每次显示页面时我都必须生成文件(而且我不想这样做，因为这是非常昂贵的操作，只能在需要时使用).

I believe can't use approach with FileDownloader, because there I would have to generate the file every time the page is displayed prior to actual click on extended button (and I don't want to do that, as it is quite expensive operation which will shall only be used on demand).

我可以使用 Page.getCurrent().open(streamResource, null, false) 达到预期的效果，但是 .open 使用 Resource 参数自 Vaadin 7 起已弃用，所以我不想依赖它...

I was able to achieve the desired effect using Page.getCurrent().open(streamResource, null, false), but .open with Resource argument is deprecated since Vaadin 7, so I don't wanna rely on it...

是否有任何解决方法或其他方法?

Is there any workaround or another approach to this?

推荐答案

Vaadin FileDownloader 可能仍然能够通过一些自定义来处理这个问题.然而，我曾经用不同的方法创建了一个报告系统.这个想法是使用组件 BrowserFrame 将 StreamResource 作为其构造函数参数.

Vaadin FileDownloader might be still capable to handle this with some customization. However I once created a reporting system with a different approach. The idea is to use component BrowserFrame that takes StreamResource as its constructor param.

文件生成开始 - 例如 - 通过单击按钮.当生成结束时，它会生成一个 byte[].从 byte[] 创建一个 StreamSource，然后用于创建 StreamResouce，然后用作 BrowserFrame 的内容>.

File generation is started - for example - by clicking a button. When generation finalizes it results in to a byte[]. From byte[] is created a StreamSource which then is used to create StreamResouce which is then used as contents of BrowserFrame.

最后这个 BrowserFrame 被添加到 ui 某处，导致浏览器做出反应.

Finally this BrowserFrame is added to the ui somewhere which causes browser to react.

就我而言，需要生成参数化的 PDF 报告，用户可以先预览这些报告，然后在需要时下载.我有一个提供 byte[] 的 PDF 生成器.浏览器从文件扩展名 .pdf 识别类型并打开 PDF 插件进行预览 &下载.

In my case there was a need to generate parameterized PDF reports which user could first preview and then download if in need. I had a PDF generator that provided the byte[]. Browser recognized type from file name extension .pdf and opened PDF plugin for preview & download.

您可以将任何二进制内容放入 byte[] 用于构造 BrowserFrame 并设置适当的文件扩展名.

You can put any binary stuff to byte[] used to construct BrowserFrame and set appropriate file name extension.

您还可以在您的 ui 中使用一些 Layout，例如，在后台生成文件时具有进度指示器，并且 BrowserFrame 组件位于其中文件准备好后附上.

You can also have some Layout in your ui that - for example - has a progress indicator while file is generating in the background and in to which the BrowserFrame component is attached when file is ready.

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