[英]Work with Spring Scheduler (Vaadin Chat and Spring Boot)
[英]Output hello in vaadin chat dialog (Spring boot and spring scheduler + vaadin 14)
我创建了一个关于 vaadine 和弹簧靴的聊天。 所以我的调度程序有问题,我想编写一个每秒显示“hello”的调度程序,但是我怎么写才能让它每秒调用 hello ,就像这个示例输出 -
hello 1 - (when 1 second has passed)
hello 2 - (after two seconds)
hello 3 - (after three seconds)
.
.
.
.
hello 45 - (after 45 seconds)
.
.
.
.
hello 100 - (after 100 seconds)
我的代码,登录时如何在聊天中启动调度程序
public class MainView extends VerticalLayout {
private final MessagesInfoManager messagesInfoManager;
private final RestService restService;
private String username;
private int count=0;
@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() {
count++;
System.out.println("Hello"+count);
}
}
您如何在 Java 中设置调度程序与 Vaadin 本身没有太大关系。 您可以使用您运行的第二个线程,或者您似乎拥有的现成工具。 如果我没记错的话,它看起来像一个 Spring 功能。
之后,您更新 Vaadin 组件以包含新消息。 例如,您可以将 messageList 放入一个字段并在test()
添加一个新段落。 或者使用您必须从那里推送消息的后端服务。
当您从辅助线程更新 UI 时,请记住您可能会遇到竞争条件。 因此,您应该在进行 UI 更改时锁定用户会话。
@Scheduled(fixedDelay = 1000)
public void test() {
count++;
System.out.println("Hello" + count);
this.getUI().get().access(() -> {
if (messageList != null) {
messageList.add(new Paragraph("From me" + ": " + "Hello" + count));
}
});
}
}
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