当两个bean的作用域相同时，托管属性值不会更新 [英] Managed property value not updated when both beans are of same scope

问题描述

使用@ManagedProperty时，我看到这种奇怪的行为.我有2个豆子:

I am seeing this strange behavior when using @ManagedProperty. I have 2 beans:

UserManager (SessionScoped)

UserManager (SessionScoped)

@ManagedBean
@SessionScoped
public class UserManager extends BaseBean implements Serializable
{
   private static final long serialVersionUID = 1861000957282002416L;

   private User currentUser;

   public String login() 
   {
      // set value of currentUser after authentication
   }

   public User getCurrentUser() {
      return currentUser;
   }

   public boolean isLoggedIn() {
      return getCurrentUser() != null;
   }
}

CartBean ( ALSO SessionScoped)

CartBean (ALSO SessionScoped)

...
import javax.faces.bean.ManagedProperty;
...

@ManagedBean
@SessionScoped
public class CartBean extends BaseBean implements Serializable
{
   @ManagedProperty(value = "#{userManager.loggedIn}")
   private boolean loggedIn;

   public void updateCart(Movie selectedMovie)
   {
      if (!loggedIn) {
         return;
      }

      System.out.println("UPDATE CART REQUEST");

      int id = selectedMovie.getMovieID();

      if (cart.containsKey(id)) {
         cart.remove(id);
      }
      else {
         cart.put(id, selectedMovie);
      }
   }

   public void setLoggedIn(boolean loggedIn) {
      this.loggedIn = loggedIn;
   }
}

成功登录后，loggedIn still 的值仍为false.

After logging in successfully, the value of loggedIn still remains false.

但是，如果我将CartBean的范围更改为@ViewScoped，则会更新loggedIn的值，并且会看到sysout.

However, if I change the scope of CartBean to @ViewScoped, the value of loggedIn gets updated and I see the sysout.

根据我的理解，并且在阅读了各种文章之后，只有在相同或更广泛范围内，才可以注入托管bean或其属性.但是相同范围"的情况在我的代码中似乎不起作用.我在这里想念什么?

As per my understanding and also after reading various articles, one can inject a managed bean or its property only if it is of the same or broader scope. But the "same scope" case does not seem to work in my code. What am I missing here?

我正在使用:

• Mojarra 2.1.16
• 3.2春季
• 休眠4.1
• Tomcat 7.0.37

推荐答案

@ManagedProperty注释只能提供静态注入，这意味着带注释的属性将在当且仅当保存时被注入@ManagedBean被实例化.

@ManagedProperty annotation can only provide static injection, which means that the annotated property will get injected when and only when the holding @ManagedBean is instantiated.

在部署应用程序时，我相信一开始就通过View cart按钮之类的东西引用了CartBean.因此，注入太早了，因为bean是@SessionScoped ，您将一直保留false的初始值，直到时间结束:).

When you deploy your application, I believe your CartBean was referenced right at the beginning through things like the View cart button, etc. As a consequence, the injection took place too early and since the bean is @SessionScoped, you will carry the initial false value till the end of time :).

您应该注入整个UserManager bean，而不是只注入boolean字段:

Instead of injecting only the boolean field, you should, instead, inject the whole UserManager bean:

@ManagedBean
@SessionScoped
public class CartBean extends BaseBean implements Serializable {
   @ManagedProperty(value = "#{userManager}")
   private UserManager userManager;

   public void updateCart(Movie selectedMovie) {
       if (!userManager.isLoggedIn()) {
           return;
       }

       ...
   }
}

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