java是Spring中的@Scheduled注释

Question

我使用vaadin framework 14和spring boot创建了一个聊天室。它工作得很好，只是我需要为它创建一个计时器。我创建了一个计时器，但有人告诉我这是错误的。我用Java创建了一个计时器，这是错误的。我需要在我的“MainView”类中使用（Spring中的@Scheduled注释）。这样他就可以每秒调用（api/未读）

我之前创建了一个类“TimerConfig”。但他们说这是错误的

public class TimerConfig {


    @Autowired
    MessageServiceImpl messageService;

    @Bean
    public TimerTask timer () {
        TimerTask timerTask = new TimerTask() {
            @Override
            public void run() {
                messageService.getAllMessages();
            }

        };
        Timer timer = new Timer();
        timer.schedule(timerTask, 1000, 1000);
        return timerTask;
    }
}

在这个类中需要“MainView”创建（@Scheduled Annotation in Spring），以便计时器每秒调用（api/unread）

主视图类

@StyleSheet("frontend://styles/styles.css")
@Route
@PWA(name = "Vaadin MessagesInfoManager", shortName = "Vaadin MessagesInfoManager")
@Push
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();
    }
}

我的休息控制器

public class RestController {

    @Autowired

    TimerTask timerTask;

    @Resource
    private final MessageService messageService;

    public RestController(MessageService messageService) {
        this.messageService = messageService;
    }



    @GetMapping("/api/unread")
    public void getUnreadMessages() {

        timerTask.run(); // it's wrong 
    }

我的githubhttps://github.com/fallen3019/vaadin-chat

Answer 1

将@Scheduled Anno放在getAllMessages（）方法serviceImpl的顶部

public class MessageServiceimpl {
 @Scheduled(fixedDelay = 1500000)// 25 min
public void getAllMessages(){
       -
 - your implementations 
       - 
}
}

Answer 2

public class MainView extends VerticalLayout {

@Autowired
MessageServiceImpl messageService;

   
   your code here  
  

@Scheduled(fixedRate = 1000)   (OR @Scheduled(cron = "0 * * * * *"))
void getMessagesBySchedule(){
    messageService.getAllMessages();
{

这个代码每秒钟工作一次

Answer 3

启用调度

只需将@EnableScheduling注释添加到主应用程序类或任何配置类，即可启用调度

安排任务

调度任务就像用@Scheduled注释方法一样简单

在下面的示例中，execute()方法计划每秒运行一次execute()方法将调用所需的服务方法

public class MainView extends ... {

    // Existing Code

    @Autowired
    private MessageServiceImpl messageService;

    @Scheduled(fixedRate = 1000)
    public void execute() {
        messageService.getAllMessages();
    }

}

日程安排的类型

1. 固定费率调度

   execute() method can be scheduled to run with a fixed interval using fixedRate parameter.

   @Scheduled(fixedRate = 2000)
   

2. 固定时延调度

   execute() method can be scheduled to run with a fixed delay between the completion of the last invocation and the start of the next, using fixedDelay parameter.

   @Scheduled(fixedDelay = 2000)
   

3. 具有初始延迟和固定速率/固定延迟的调度

   initialDelay parameter with fixedRate and fixedDelay to delay the first execution.

   @Scheduled(fixedRate = 2000, initialDelay = 5000)
   

   @Scheduled(fixedDelay= 2000, initialDelay = 5000)
   

4. cron调度

   execute() method can be scheduled to run based on cron expression using cron parameter.

   @Scheduled(cron = "0 * * * * *")