How to retain/maintain collapse and expand states of <p:panelMenu> even after a page refresh?

问题

Suppose I have the following simple <p:panelMenu>.

<p:panelMenu style="width:200px">
    <p:submenu label="Contents">
        <p:menuitem value="MenuItem1" url="SomeURL" icon="ui-icon-disk" />
        <p:menuitem value="MenuItem2" url="SomeURL" icon="ui-icon-disk" />
        <p:menuitem value="MenuItem3" url="SomeURL" icon="ui-icon-disk" />
    </p:submenu>

    <p:separator />

    <p:submenu label="Users">
        <p:menuitem value="MenuItem1" url="SomeURL" icon="ui-icon-disk" />
        <p:menuitem value="MenuItem2" url="SomeURL" icon="ui-icon-disk" />
        <p:menuitem value="MenuItem3" url="SomeURL" icon="ui-icon-disk" />
    </p:submenu>                
</p:panelMenu>

Once a sub menu is expanded should remain expanded until it is explicitly collapsed even after a page refresh.

Similarly, sometime later, if the sub menu is collapsed should remain collapsed until it is explicitly expanded even after the page reloaded/refreshed. Is this possible?

---

By the way, the following script expands a <p:panelMenu> by default (all <p:submenu>).

$(document).ready(function(){
    $(".ui-panelmenu-content").css("display","block");
    $(".ui-panelmenu-header").addClass("ui-state-active");
    $(".ui-icon-triangle-1-e").removeClass("ui-icon-triangle-1-e").addClass("ui-icon-triangle-1-s");
});

And the following script expands the first sub menu of <p:panelMenu>, if it is collapsed.

var isMenuExpanded = jQuery('div.ui-panelmenu-content.ui-widget-content.ui-helper-hidden').is(':visible');

if(!isMenuExpanded)
{
    jQuery('.ui-panelmenu-panel a').first().click();
}

回答1:

Set every value item with ids and also with class to the click response

<p:panelMenu id="menu" style="width:200px">
    <p:submenu id="submenu" label="Contents" styleClass="submenu">
        <p:menuitem id="menu1" value="MenuItem1" url="SomeURL" icon="ui-icon-disk" />
        <p:menuitem id="menu2" value="MenuItem2" url="SomeURL" icon="ui-icon-disk" />
        <p:menuitem id="menu3" value="MenuItem3" url="SomeURL" icon="ui-icon-disk" />
    </p:submenu>
</p:panelMenu>

---

set localstorage as global variable (index)

$(document).ready(function(){
    localStorage.param=Number(0);
});

---

variables session with localstorage javascript

var param= Number(localStorage.param);

every page refresh, get the localstorage variable session to change the menu state

$(document).ready(function(){
var e1 = document.getElementById("menu_submenu");
if(Boolean(param)==true){
    e1.style.display="block";
    e1.parentNode.getElementsByTagName("h3")[0].className="ui-widget ui-panelmenu-header ui-state-default ui-state-active ui-corner-top";
    e1.parentNode.getElementsByTagName("h3")[0].getElementsByTagName("span")[0].className="ui-icon ui-icon-triangle-1-s";
}
else{
    e1.style.display="none";
    e1.parentNode.getElementsByTagName("h3")[0].className="ui-widget ui-panelmenu-header ui-state-default ui-corner-all";
    e1.parentNode.getElementsByTagName("h3")[0].getElementsByTagName("span")[0].className="ui-icon ui-icon-triangle-1-e";
}

the click event to set the localstorage variable session

$(document).on("click", ".submenu", function(e) {
var target = e.target || e.srcElement;
while (target && !target.id) {
    target = target.parentNode;
}
if (!(target.id == 'menu1')){
    var n= Number(param)==Number(0)?Number(1):Number(0);
    param=Number(n);
    localStorage.param=Number(n);
   }
});

回答2:

<p:panelMenu stateful="false"></p:panelMenu>

stateful attruibute default is true. If you want to control collapsed/expanded states by hand, you should set it false, then you can use expanded attribute on submenu elements.

回答3:

Ways to store the current state of your panels (which are open and which are closed) are already covered pretty nicely with this earlier Stack Overflow question.

来源：https://stackoverflow.com/questions/18863381/how-to-retain-maintain-collapse-and-expand-states-of-ppanelmenu-even-after-a