瓦丁。在我上传文件之前触发 addSucceededListener()

Question

晚安，社区。我尤其是 Java 和 Vaadin 的新手。请向我解释为什么 addSucceededListener() 比我下载文件更早（加载页面时）触发？

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只是一个鱼文本，会省略编辑出版 -_-

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@Route("")
public class UploadView extends VerticalLayout {
    @Autowired
    PictureRepository pictureRepository;

    @Autowired
    GoogleCloudAiAssistantRecognition googleCloudAiAssistantRecognition;

    public UploadView() {
        this.pictureRepository = pictureRepository;
        this.googleCloudAiAssistantRecognition = googleCloudAiAssistantRecognition;

        MenuBar menuBar = new MenuBar();
        menuBar.addThemeVariants(MenuBarVariant.LUMO_PRIMARY);

        MenuItem resultsItem = menuBar.addItem("Get Results");
        MenuItem tagItem = menuBar.addItem("Edit Tag");

        resultsItem.addClickListener(e -> UI.getCurrent().navigate("ai-result"));
        tagItem.addClickListener(e -> UI.getCurrent().navigate("edit-tag"));

        add(menuBar, new H1("Assistant recognition by Google Vision"));

        MemoryBuffer buffer = new MemoryBuffer();
        Upload upload = new Upload(buffer);
        upload.setAcceptedFileTypes("image/jpeg", "image/png", "image/gif");
        upload.setMaxFileSize(10485760);
        Div output = new Div();

        upload.addSucceededListener(event -> {
                InputStream inputStream = buffer.getInputStream();
                byte[] bytes = new byte[0];
                try {
                    bytes = IOUtils.toByteArray(inputStream);
                } catch (IOException e) {
                    e.printStackTrace();
                }

                add(new H1(event.getMIMEType()));
                Component component = createComponent(event.getMIMEType(), event.getFileName(), inputStream);
                showOutput(event.getFileName(), component, output);

                PictureModel pictureModel = new PictureModel(event.getFileName(), event.getMIMEType(), bytes);
                Long picId = pictureRepository.save(pictureModel).getId();

                List<TagModel> tags = null;
                try {
                    tags = googleCloudAiAssistantRecognition.detect(picId);
                } catch (Exception e) {
                    e.printStackTrace();
                }
                pictureModel.setTagModel(tags);
        });

        /*upload.getElement().addEventListener("upload-success", e -> {
            System.out.println(e.getEventData());
        });*/

        add(upload, output);
    }

Answer 1

我怀疑你可能有误解。它添加了successed-listener，但还没有执行listener-code。

您似乎还使用了始终为空的bytes 变量，因为您读取了空缓冲区（在succededListener 之外）的inputStream。

请尝试此代码，然后，如果您的“问题”仍然存在，请尝试重新表述您的问题。

public UploadView() throws IOException {
    add(new H1("Assistant recognition by Google Vision"));

    MemoryBuffer buffer = new MemoryBuffer();
    Upload upload = new Upload(buffer);
    upload.setAcceptedFileTypes("image/jpeg", "image/png", "image/gif");
    upload.setMaxFileSize(10485760);
    Div output = new Div();

    // move this INTO the succeededListener, because otherwise the buffer is empty
    //InputStream inputStream = buffer.getInputStream();
    //byte[] bytes = IOUtils.toByteArray(inputStream);

    upload.addSucceededListener(event -> {
        InputStream inputStream = buffer.getInputStream();
        byte[] bytes = IOUtils.toByteArray(inputStream);

        add(new H1(event.getMIMEType()));
        Component component = createComponent(event.getMIMEType(), event.getFileName(), inputStream);
        showOutput(event.getFileName(), component, output);

        PictureModel pictureModel = new PictureModel(event.getFileName(), event.getMIMEType(), bytes);
        Long picId = pictureRepository.save(pictureModel).getId();

        List<TagModel> tags = null;
        try {
            tags = googleCloudAiAssistantRecognition.detect(picId);
        } catch (Exception e) {
            e.printStackTrace();
        }
        pictureModel.setTagModel(tags);
        pictureRepository.save(pictureModel);
    });

    add(upload, output);
}