JSF - 会话范围的托管bean没有在会话反序列化上重新注入依赖项

Question

我不确定我做的是不是错了,或者我错过了某个地方的注释或配置项.情况如下:

我有一个JSF应用程序与一个名为session的作用域bean SessionData.这个bean ApplicationData在创建时注入了一个应用程序范围的bean引用(类型).首次创建会话时,这可以正常工作.依赖注入是使用文件中的<managed-bean>元素完成的,faces-config.xml如下所示:

<managed-bean>
    <managed-bean-name>sessionData</managed-bean-name>
    <managed-bean-class>my.package.SessionData</managed-bean-class>
    <managed-bean-scope>session</managed-bean-scope>
    <managed-property>
        <property-name>applicationData</property-name>
        <property-class>my.package.ApplicationData</property-class>
        <value>#{applicationData}</value>
    </managed-property>
</managed-bean>
<managed-bean>
    <managed-bean-name>applicationData</managed-bean-name>
    <managed-bean-class>my.package.ApplicationData</managed-bean-class>
    <managed-bean-scope>application</managed-bean-scope>
</managed-bean>

因为在序列化时我的SessionData对象包含ApplicationData对象没有意义,所以我在对象中将ApplicationData引用标记为瞬态SessionData:

transient private ApplicationData applicationData;

一切都很好,直到Web应用程序停止(在我的Tomcat 6.x容器中)并且会话被序列化.当我重新启动应用程序并反序列化会话时,我的引用ApplicationData不会被JSF重新注入.我知道反序列化应该留下没有值的瞬态字段.有没有办法告诉JSF这个会话范围的对象要求在反序列化后再次设置其依赖项？

我使用MyFaces JSF 1.2和Tomcat 6.0.26作为我的Web应用程序容器.

Answer 1

虽然Bozho提供的解决方案可以工作,但我不想将代理对象引入到当前没有使用它们的应用程序中.我的解决方案不太理想,但它完成了工作.

我把瞬态场留在了原地:

transient private ApplicationData _applicationData;

我还将setter留在原位,因此JSF可以SessionData在第一次创建对象时初始设置引用:

public void setApplicationData(ApplicationData applicationData) {
    _applicationData = applicationData;
}

我做的改变是在getter方法中.SessionData对象中的方法现在需要停止直接访问_applicationData字段,而是通过getter获取引用.getter将首先检查null引用.如果为null,则通过获取托管bean FacesContext.这里的约束是,FacesContext仅在请求的生命周期内可用.

/**
 * Get a reference to the ApplicationData object
 * @return ApplicationData
 * @throws IllegalStateException May be thrown if this method is called
 *  outside of a request and the ApplicationData object needs to be
 *  obtained via the FacesContext
 */
private ApplicationData getApplicationData() {
    if (_applicationData == null) {
        _applicationData = JSFUtilities.getManagedBean(
            "applicationData",  // name of managed bean
            ApplicationData.class);
        if (_applicationData == null) {
            throw new IllegalStateException(
                "Cannot get reference to ApplicationData object");
        }
    }
    return _applicationData;
}

如果有人关心,这是我的getManagedBean()方法的代码:

/**
 * <p>Retrieve a JSF managed bean instance by name.  If the bean has
 * never been accessed before then it will likely be instantiated by
 * the JSF framework during the execution of this method.</p>
 * 
 * @param managedBeanKey String containing the name of the managed bean
 * @param clazz Class object that corresponds to the managed bean type
 * @return T
 * @throws IllegalArgumentException Thrown when the supplied key does
 *  not resolve to any managed bean or when a managed bean is found but
 *  the object is not of type T
 */
public static <T> T getManagedBean(String managedBeanKey, Class<T> clazz)
        throws IllegalArgumentException {
    Validate.notNull(managedBeanKey);
    Validate.isTrue(!managedBeanKey.isEmpty());
    Validate.notNull(clazz);
    FacesContext facesContext = FacesContext.getCurrentInstance();
    if (facesContext == null) {
        return null;
    }
    Validate.notNull(facesContext.getApplication());
    ELResolver resolver = facesContext.getApplication().getELResolver();
    Validate.notNull(resolver);
    ELContext elContext = facesContext.getELContext();
    Validate.notNull(elContext);
    Object managedBean = resolver.getValue(
        elContext, null, managedBeanKey);
    if (!elContext.isPropertyResolved()) {
        throw new IllegalArgumentException(
            "No managed bean found for key: " + managedBeanKey);
    }
    if (managedBean == null) {
        return null;
    } else {
        if (clazz.isInstance(managedBean)) {
            return clazz.cast(managedBean);
        } else {
            throw new IllegalArgumentException(
                "Managed bean is not of type [" + clazz.getName() +
                "] | Actual type is: [" + managedBean.getClass().getName()+
                "]");
        }
    }
}

并且不要选择我的验证电话.在完成开发之后我会把它们拿出来!:)