如何使用 Vaadin 10 下载文件？

Question

我想让用户从服务器下载一个文件。我 looked up 寻求解决方案并尝试举个例子 - 结果是这样的：

@Route("test-download")
public class Download extends VerticalLayout {

    public Download() {
        Anchor downloadLink = new Anchor(createResource(), "Download");
        downloadLink.getElement().setAttribute("download", true);
        add(downloadLink);
    }

    private AbstractStreamResource createResource() {
        return new StreamResource("/home/johny/my/important-file.log", this::createExportr);
    }

    private InputStream createExportr(){
        return null;
    }
}

当我在浏览器中转到该页面时，它给出了 java.lang.IllegalArgumentException: Resource file name parameter contains '/'。
如何制作知道磁盘上文件位置的下载按钮（或锚点）？

Answer 1

看看 documentation, paragraph "Using StreamResource". The first parameter is just a file name that will be used by the browser to propose that file name to the user when downloading. So you could pass it like "important-file.log". The content of the download is provided by the InputStream parameter. For instance, you could read from your file, see here:

File initialFile = new File("src/main/resources/sample.txt");
InputStream targetStream = new FileInputStream(initialFile);

如何使用 Vaadin 10 下载文件？

How to download a file with Vaadin 10?

vaadin

vaadin10

vaadin-flow