java如何正确编写调度程序（Spring Boot和Vaadin 14）

Question

我需要写一个调度程序，这样每一秒它都会导致ID上的未读消息。我写了一个sС调度程序，但它完全错了。需要完全更改“MainView”类中的代码

在这个类中，我有一个错误地实现的调度程序

public class MainView extends VerticalLayout {

    private final MessagesInfoManager messagesInfoManager;
    private final RestService restService;
    private String username;

    @Autowired
    public MainView(RestService restService) {
        this.messagesInfoManager = MessageConfigurator.getInstance().getChatMessagesInfoManager();
        addClassName("main-view");
        setSizeFull();
        setDefaultHorizontalComponentAlignment(Alignment.CENTER);

        H1 header = new H1("Vaadin Chat");
        header.getElement().getThemeList().add("dark");

        add(header);

        askUsername();
        this.restService = restService;
    }

    private void askUsername() {
        HorizontalLayout layout = new HorizontalLayout();
        TextField usernameField = new TextField();
        Button startButton = new Button("Start chat");

        layout.add(usernameField, startButton);

        startButton.addClickListener(click -> {
            username = usernameField.getValue();
            remove(layout);
            showChat(username);
        });

        add(layout);
    }

    private void showChat(String username) {
        MessageList messageList = new MessageList();

        List<Message> lasts = restService.getLast();
        for (Message message : lasts) {
            messageList.add(new Paragraph(message.getFrom() + ": " + message.getMessage()));
        }

        add(messageList, createInputLayout(username, messageList));
        expand(messageList);
    }

    private Component createInputLayout(String username, MessageList messageList) {
        HorizontalLayout layout = new HorizontalLayout();
        layout.setWidth("100%");

        TextField messageField = new TextField();
        messageField.addKeyDownListener(Key.ENTER, keyDownEvent -> sender(messageField, messageList));
        Button sendButton = new Button("Send");
        sendButton.addThemeVariants(ButtonVariant.LUMO_PRIMARY);

        layout.add(messageField, sendButton);
        layout.expand(messageField);

        messageField.addFocusListener(event -> {
            for (Message message : messagesInfoManager.getMessagesByUI(getUI())) {
                if (!message.getFrom().equals(username)) {
                    message.setUnread(false);
                    this.restService.updateMessage(message.getId(), message);
                }
            }
        });

        sendButton.addClickListener(click -> sender(messageField, messageList));
        messageField.focus();

        return layout;
    }

    private void sender(TextField textField, MessageList messageList) {
        Message message = new Message(username, textField.getValue());
        message = restService.saveMessage(message);
        messagesInfoManager.updateMessageUIInfo(new MessageInfo(messageList, message, this));
        textField.clear();
        textField.focus();
    }

    @Scheduled(fixedDelay = 1000)
    public void loadUnReadMessage() {
        if(messageList == null) return;
        List<Message> messages = restService.getUnRead();
        for(Message message : messages) {
            messagesInfoManager.updateMessageUIInfo(new MessageInfo(messageList, message, this));
            message.setUnread( true );
            restService.saveMessage( message );
        }
    }
}

需要从MySQL数据库中按id获取未读消息。有必要让调度程序每隔一秒钟调用这个函数-getUnreadById

MessageRepository（getUnreadById）

@Query(value = "SELECT * FROM chatMessages WHERE id > :id", nativeQuery = true)
List<Message> getUnreadById(@Param("id") long id);

RestService

public List<Message> getUnreadById() {
    String url = "http://localhost:8080/api/unread/byid";

    String json = restTemplate.getForObject(url, String.class);
    return new Gson().fromJson(json, new TypeToken<List<Message>>(){}.getType());
}

messageserviceinpl

@Override
public List<Message> getUnreadById(InputMessage message) {
    return repository.getUnreadById(message.getMessageId());
}

消息服务

List<Message> getUnreadById(InputMessage message);

MessageInfoManager

public class MessagesInfoManager {
    private final List<MessageInfo> messagesInfoQueue = new ArrayList<>();

    private final Map<Optional<UI>, MessageList> messageListMap = new HashMap<>();

    private void addMessageInfo(MessageInfo messageInfo) {
        if (!messagesInfoQueue.contains(messageInfo)) {
            this.messagesInfoQueue.add(messageInfo);
            this.messageListMap.putIfAbsent(messageInfo.getUI(), messageInfo.getMessageList());
        }
    }

    public List<Message> getMessagesByUI(Optional<UI> uiOptional) {
         return messagesInfoQueue
                .stream()
                .filter(messageInfo -> !messageInfo.getUI().equals(uiOptional))
                .map(MessageInfo::getMessage)
                .collect(Collectors.toList());
    }
}

您可以帮助正确地编写一个调度程序，以便它每秒钟按ID（getUnreadById）生成未读消息