将参数从一个页面传递到另一个页面——表达式引用的对象的范围比引用托管bean错误的范围短

Question

我试图将参数从一个页面传递到另一个页面，但是当我按下"详细信息"按钮时，它给了我这个错误:"无法创建托管bean agencyDetailBean。-由表达式#{代理}，请求引用的对象的范围小于会话"

的引用管理bean (agencyDetailBean)的范围。

这是我的.xhtml页面的一部分:

<p:dataGrid var="agency" value="#{agencyBean.agencyList}" columns="1"
    rows="5" paginator="true" paginatorPosition="bottom">
    <p:growl id="growl" showDetail="true" />
    <p:fieldset legend="${agency.tUser.name}" toggleable="true">
        <p:ajax event="toggle" listener="#{fieldsetBean.handleToggle}"
            update="growl" />
        <h:panelGrid columns="2" cellpadding="3" cellspacing="1">
            <h:panelGrid columns="2" cellpadding="3" cellspacing="1">
                Name: <h:outputText value="${agency.tUser.name}" />
                Phone: <h:outputText value="${agency.tUser.phone}" />
            </h:panelGrid>
            <h:commandButton value="Details" action="agencyDetail">
                <f:setPropertyActionListener target="#{agencyBean.tAgency}"
                    value="${agency}" />
            </h:commandButton>
        </h:panelGrid>
    </p:fieldset>
</p:dataGrid>

我的第一个豆子:

@ManagedBean(name = "agencyBean")
@SessionScoped
public class AgencyBean implements Serializable {
    private TAgency tAgency = new TAgency();
    private List<TAgency> agencyList;
    public List<TAgency> getAgencyList() {
        return agencyList;
    }
    public void setAgencyList(List<TAgency> agencyList) {
        this.agencyList = agencyList;
    }
    @PostConstruct
    public void init() {
        EntityManager em = HibernateUtil.getEntityManager();
        Query q = em.createQuery("select u from TAgency u");
        agencyList = q.getResultList();
    }
    public TAgency gettAgency() {
        return tAgency;
    }
    public void settAgency(TAgency tAgency) {
        this.tAgency = tAgency;
    }
}

我的第二个bean类:

@ManagedBean(name = "agencyDetailBean", eager = true)
@SessionScoped
public class AgencyDetailBean implements Serializable {
    private static final long serialVersionUID = 1L;
    @ManagedProperty(value = "#{tAgency}")
    private AgencyBean agencyBean;
    private TAgency tAgency;
    public TAgency gettAgency() {
        if (agencyBean != null) {
            tAgency = agencyBean.gettAgency();
        }
        return tAgency;
    }
    public void setAgencyBean(AgencyBean agency) {
        this.agencyBean = agency;
    }
}

最初，. xml页面是这样的，它工作了。

<p:growl id="growl" showDetail="true" />
<c:forEach items="#{agencyBean.agencyList}" var="agency">
    <p:fieldset legend="${agency.tUser.name}" toggleable="true">
        ...
            <h:commandButton value="Details" action="agencyDetail">
                <f:setPropertyActionListener target="#{agencyDetailBean.agency}"<br/>
                    value="${agency}" />
            </h:commandButton>
        </h:panelGrid>
    </p:fieldset>
</c:forEach>

有什么建议是什么问题和如何解决它?提前感谢!

Answer 1

使用@ManagedBean，不能将作用域较小的bean注入作用域较大的bean。根据您的情况，将@SessionScoped注入@RequestScoped。然后，您可以从@RequestScoped bean更新@SessionScoped的任何属性。

关于您的更新，在第二个bean中，您无法从这样的getter获取tAgency。下面的函数可以完成这项工作。

@PostConstruct
public void init() {
    tAgency = agencyBean.gettAgency();
}