[英]Output hello in vaadin chat dialog (Spring boot and spring scheduler + vaadin 14)
[英]Work with Spring Scheduler (Vaadin Chat and Spring Boot)
我用 Spring Boot 創建了 Vaadin Chat。 我寫了一個調度程序,我無法向它添加函數。 我需要從 MySQL 數據庫中獲取所有消息,其 ID 大於我們從最后一條消息中獲取的 ID。
我的調度器
@Scheduled(fixedDelay = 5000)
public void scheduleFixedDelayTask() {
MessageList messageList = new MessageList();
List<LinkedHashMap> lasts = restService.getUnreadMessages(messageLast.getId());
for (LinkedHashMap message : lasts) {
messageList.add(new Paragraph(message.get("fromV") + ": " + message.get("messageV")));
}
}
這個調度器在課堂上 - Mainview
public class MainView extends VerticalLayout {
private final MessagesInfoManager messagesInfoManager;
private final RestService restService;
private String username;
private TextField textField;
private Message messageLast;
@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.getFromV() + ": " + message.getMessageV()));
}
messageLast = lasts.get(lasts.size() - 1);
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.getFromV().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());
restService.saveMessage(message);
messageLast = message;
this.textField = textField;
messagesInfoManager.updateMessageUIInfo(new MessageInfo(messageList, message, this));
textField.clear();
textField.focus();
}
@Scheduled(fixedDelay = 5000)
public void scheduleFixedDelayTask() {
MessageList messageList = new MessageList();
List<LinkedHashMap> lasts = restService.getUnreadMessages(messageLast.getId());
for (LinkedHashMap message : lasts) {
messageList.add(new Paragraph(message.get("fromV") + ": " + message.get("messageV")));
}
}
存儲庫
@Query(value = "SELECT * FROM chatMessages WHERE id > :id", nativeQuery = true)
List<Message> getUnreadById(@Param("id") long id);
我可以在你的例子中發現至少兩個問題,但我不能確定這些是唯一的問題
第一個問題是您將消息添加到新創建的MessageList
實例,但該實例並未在任何地方使用。 這就像在一張紙上寫筆記,然后立即將紙扔進垃圾桶。 相反,您需要存儲對已添加為子組件的MessageList
實例的引用,並將新消息添加到該實例中。
下一個問題是@Scheduled
將在后台線程中運行,而對 Vaadin 組件的更新只有在處理來自用戶瀏覽器的請求時才會自動反映在瀏覽器中,例如當用戶單擊按鈕時。 要解決這個問題,您需要啟用@Push
並且您需要在更新組件時使用access
方法,以便 Vaadin 可以防止多個線程相互@Push
,並知道何時需要推出更改。 有關此主題的更多信息,請參閱https://vaadin.com/docs/v14/flow/advanced/tutorial-push-access.html 。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.