jsf2.1 - 正在创建新的ViewScoped bean

Question

任何人都知道什么可能导致JSF实例化一个新的viewScoped bean，即使viewstate id是相同的。

在我的viewScoped bean构造函数中，我将代码放在下面以打印javax.faces.ViewState的值：

// construtor
public MyViewScopeBeanJsfBean() {
    System.out.println("===== In MyViewScopeBeanJsfBean Constructor Begin =====");
    printViewState();
    System.out.println("===== In MyViewScopeBeanJsfBean Constructor End =====");
}

private void printViewState() {
    String[] viewStates = getHttpServletRequest().getParameterValues("javax.faces.ViewState");
    if (viewStates != null) {   
        for (String viewState :viewStates) {
            System.out.println("javax.faces.ViewState="+viewState);
        }
    }
    else {
        System.out.println("javax.faces.ViewState=null");           
    }       
}

以下是我得到的结果：

JSF created the viewscoped bean for the 1st time:
===== In MyViewScopeBeanJsfBean Constructor Begin =====
javax.faces.ViewState=null
===== In MyViewScopeBeanJsfBean Constructor End =====


I stayed on the same page and clicked on a ajax link to inlcude a page into the current page.
===== In MyViewScopeBeanJsfBean Constructor Begin =====
javax.faces.ViewState=y25eUekk0MqNOV7cxixhe+YOI31giRnbuL1ad9X158PdRuir
===== In MyViewScopeBeanJsfBean Constructor End =====

I then click on a link In the newly included page to upload a file:
===== In MyViewScopeBeanJsfBean Constructor Begin =====
javax.faces.ViewState=y25eUekk0MqNOV7cxixhe+YOI31giRnbuL1ad9X158PdRuir
===== In MyViewScopeBeanJsfBean Constructor End =====

在每次点击时，我都会停留在同一页面上，您可以看到视图状态ID是相同的。但是为什么JSF会调用构造函数来创建一个viewcoped bean的新实例？

注意：我的主模板中有以下内容来纠正与ajaxly相关的viewscoped bean问题包括页面：

<h:outputScript library="omnifaces" name="fixviewstate.js" target="head" />