JSF - 会话范围的托管bean没有重新注入会话反序列化的依赖关系 [英] JSF - Session-scoped managed bean does not have dependencies re-injected on session deserialization
问题描述
我有一个名为 SessionData 的会话作用域的JSF应用程序。此Bean在创建时注入了一个应用程序范围的bean引用（类型为$ code> ApplicationData ）。当会话第一次创建时，这可以正常工作。依赖注入通过 faces-config.xml 文件中的< managed-bean> 元素完成，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>应用程序< / managed-bean-scope>
< / managed-bean>
因为我的 SessionData object在序列化时包含 ApplicationData 对象，我将 ApplicationData 引用标记为 code> SessionData object：
transient private ApplicationData applicationData;
直到Web应用程序停止（在Tomcat 6.x容器中）和会话被序列化。当我重新启动应用程序并且会话被反序列化时，我对JSF不再重新注入对 ApplicationData 的引用。我知道反序列化应该是暂时的，没有价值的。
我正在使用MyFaces JSF 1.2，这是一种方法来表示JSF，这个会话范围的对象需要在反序列化之后再次设置它的依赖项和Tomcat 6.0.26作为我的Web应用程序容器。
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未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。
我离开了瞬态字段：
transient private ApplicationData _applicationData;
我也将设置器置于原位，所以JSF最初可以在 SessionData 对象是第一次创建：
public void setApplicationData（ApplicationData applicationData）{
_applicationData = applicationData;
}
我所做的更改是在getter方法中。现在， SessionData 对象中的方法现在需要停止直接访问 _applicationData 字段，而通过getter获取引用。 getter将首先检查一个null引用。如果为空，则通过 FacesContext 获取受管Bean。这里的约束是 FacesContext 仅在请求的使用期限内可用。
/ **
*获取对ApplicationData对象的引用
* @return ApplicationData
* @throws IllegalStateException如果此方法称为
*，则可能会抛出一个请求和ApplicationData对象需要
*通过FacesContext
* /
私有ApplicationData getApplicationData（）{
if（_applicationData == null）{
_applicationData = JSFUtilities.getManagedBean（
applicationData，//托管bean的名称
ApplicationData.class）;
if（_applicationData == null）{
throw new IllegalStateException（
无法获取ApplicationData对象的引用）;
}
}
return _applicationData;
}
如果有人关心，这里是我的 getManagedBean（）方法：
/ **
*< p> JSF通过名称管理bean实例。如果bean的
*从未被访问过，那么在执行此方法期间可能会由
*的JSF框架实例化。< / p>
*
* @param managedBeanKey包含托管bean的名称的字符串
* @param clazz对应于受管Bean类型的类对象
* @return T
* @throws IllegalArgumentException当提供的键
*不解析为任何受管Bean或找到受管Bean但
*时，抛出此对象不是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）;
对象managedBean = resolver.getValue（
elContext，null，managedBeanKey）;
if（！elContext.isPropertyResolved（））{
throw new IllegalArgumentException（
找不到托管bean：+ managedBeanKey）;
}
if（managedBean == null）{
return null;
} else {
if（clazz.isInstance（managedBean））{
return clazz.cast（managedBean）;
} else {
throw new IllegalArgumentException（
托管bean不是类型+ clazz.getName（）+
] |实际类型是：[+ managedBean .getClass（）。getName（）+
]）;
}
}
}
不要选择我的验证电话。完成开发后我会把它们拿出来：）
I'm not sure if what I'm doing is wrong, or if I just missed an annotation or configuration item somewhere. Here's the situation:
I have a JSF application with a session-scoped bean named SessionData. This bean has an application-scoped bean reference (of type ApplicationData) injected into it at creation time. This works ok when the session is first created. The dependency injection is done with <managed-bean> elements in the faces-config.xml file as shown here:
<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>
Because it doesn't make sense to have my SessionData object include the ApplicationData object when it is serialized, I have marked the ApplicationData reference as transient in my SessionData object:
transient private ApplicationData applicationData;
All is good until the web application is stopped (in my Tomcat 6.x container) and the sessions are serialized. When I restart the application and the sessions are deserialized, my reference to ApplicationData is not re-injected by JSF. I know that deserialization is supposed to leave transient fields without a value. Is there a way to signal JSF that this session-scoped object requires its dependencies be set again after deserialization?
I am using MyFaces JSF 1.2 and Tomcat 6.0.26 as my web application container.
Although the solution offered by Bozho could work, I don't want to introduce proxy objects into an application that isn't currently using them. My solution is less than ideal, but it gets the job done.
I left the transient field in place:
transient private ApplicationData _applicationData;
I also left the setter in place so JSF can initially set the reference when the SessionData object is created the first time:
public void setApplicationData(ApplicationData applicationData) {
_applicationData = applicationData;
}
The change that I made was in the getter method. Methods in the SessionData object now need to stop directly accessing the _applicationData field and instead get the reference via the getter. The getter will first check for a null reference. If it is null, then the managed bean is obtained via the FacesContext. The constraint here is that the FacesContext is only available during the lifespan of a request.
/**
* 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;
}
If anyone cares, here is the code for my getManagedBean() method:
/**
* <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()+
"]");
}
}
}
And don't pick on my Validate calls. I'll take them out after I'm done with development! :)
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