如何在Vaadin的CDIView中獲取UI實例？

Question

我有MyUI類

@Theme("mytheme") 
@CDIUI("") 
public class MyUI extends UI { 

@Inject 
LoginView loginView; 

@Override 
protected void init(VaadinRequest vaadinRequest) { 
    setContent(loginView); 
} 

... 

我與@PostConstruct

@UIScoped 
@CDIView(LoginView.VIEWNAME) 
public class LoginView extends VerticalLayout implements CustomView { 

    @PostConstruct 
    public void initView() { 

     //initializations elements 
     Component loginForm = buildLoginForm(); 
     addComponent(loginForm); 
     setComponentAlignment(loginForm, Alignment.MIDDLE_CENTER); 

     Notification notification = new Notification("Demo"); 
     notification.setDescription("<span>DEMO</span>"); 
     notification.setHtmlContentAllowed(true); 
     notification.setStyleName("tray dark small closable login-help"); 
     notification.setPosition(Position.BOTTOM_CENTER); 
     notification.setDelayMsec(20000); 
     notification.show(Page.getCurrent()); // NullPointerException 

    } 
} 

堆棧跟蹤註釋的一個init方法一的看法是：

Caused by: java.lang.reflect.InvocationTargetException 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at org.jboss.weld.injection.producer.DefaultLifecycleCallbackInvoker.invokeMethods(DefaultLifecycleCallbackInvoker.java:98) 
    ... 72 more 

Caused by: java.lang.NullPointerException 
    at com.vaadin.ui.Notification.show(Notification.java:378) 
    at com.test.claspina.view.LoginView.initView(LoginView.java:103) 
    ... 77 more 

我的問題是如何讓UI實例在呈現視圖元素的過程中使用。

我找到了部分解決方案投入要素的全部定義成一個配置方法，這種方法：

public void configure() { 
    //initializations elements 
    Component loginForm = buildLoginForm(); 
    addComponent(loginForm); 
    setComponentAlignment(loginForm, Alignment.MIDDLE_CENTER); 

    Notification notification = new Notification("Demo"); 
    notification.setDescription("<span>DEMO</span>"); 
    notification.setHtmlContentAllowed(true); 
    notification.setStyleName("tray dark small closable login-help"); 
    notification.setPosition(Position.BOTTOM_CENTER); 
    notification.setDelayMsec(20000); 
    notification.show(Page.getCurrent()); 
} 

在我的UI調用setContent前

loginView.configure(); 
setContent(loginView); 

Answer 1

最後的幫助下我我找到了解決辦法：

這樣就有必要用CDIViewProvider這個方法

@Theme("mytheme") 
@CDIUI("") 
public class MyUI extends UI { 

@Inject 
LoginView loginView; 

@Inject 
private CDIViewProvider viewProvider; 

@Override 
protected void init(VaadinRequest vaadinRequest) { 
    Navigator navigator = new Navigator(this, this); 
    navigator.addProvider(viewProvider); 
    navigator.navigateTo("login"); 
} 

而進入類，定義視圖的名稱，並把圖中的元素的所有定義中進入方法

@UIScoped 
@CDIView(LoginView.VIEWNAME) 
public class LoginView extends VerticalLayout implements CustomView { 

    public static final String VIEWNAME = "login"; 

    //... 
    //other methods 
    //... 

    @Override 
    public void enter(ViewChangeListener.ViewChangeEvent event) { 
     //initializations elements 
     Component loginForm = buildLoginForm(); 
     addComponent(loginForm); 
     setComponentAlignment(loginForm, Alignment.MIDDLE_CENTER); 

     Notification notification = new Notification("Demo"); 
     notification.setDescription("<span>DEMO</span>"); 
     notification.setHtmlContentAllowed(true); 
     notification.setStyleName("tray dark small closable login-help"); 
     notification.setPosition(Position.BOTTOM_CENTER); 
     notification.setDelayMsec(20000); 
     notification.show(Page.getCurrent()); 
    } 
}