java Spring调度器示例(Spring boot和Vaadin 14项目)
我创建了一个用于交流的聊天。对于我使用vaadin的界面,我想测试聊天,当聊天打开时,它需要每1秒启动一次(hello 1,hello 2,hello 3……)我写了一个时间表,但它怎么可能是正确的呢?我好像写错了
MainView
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 test() {
System.out.println("Hello");
}
}
Mainview中的调度程序
@Scheduled (fixedDelay = 1000)
public void test() {
System.out.println("Hello");
}
我的例子
@Scheduled (fixedDelay = 1000)
public void test() {
count++;
System.out.println("Hello"+count);
}
# 1 楼答案
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
安排任务就像用@Scheduled annotation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。在本例中,execute()方法应该调用所需的服务方法lke getAllMessages()
日程安排类型
固定费率调度
固定延迟调度
具有初始延迟和固定速率/固定延迟的调度
使用cron进行调度