切换图标显示

<div class="rtoolbar">
<ul>
<li><a class="xj" href="#">新建</a></li>
<li><a class="dk" href="#">打开</a></li>
//编辑的lock和unlock切换，注意没有类bjunlock
<li><a class="bj" href="#">编辑</a></li>
<li><a class="ss" href="#">搜索</a></li>
<li><a class="dc" href="#">导出</a></li>
<li><a class="bz" href="#">帮助</a></li>
</ul>
</div>
<div class="st_tree">
<ul class="firmenu">
<li><span onclick="addnew(this)" class="add"><img src="../images/open_05.png" class="img-span"></span><span class="align-span">添加条目</span>
<ul class="secmenu">
<li><span onclick="addli1(this)" class="add" ><img src="../images/open_07.png"></span><a href="#">中国建设银行</a>
<ul></ul>
</li>
<li><span onclick="addli1(this)" class="add" ><img src="../images/open_07.png"></span><a href="#">中国工商银行</a>
<ul></ul>
</li>
<li><span onclick="addli1(this)" class="add" ><img src="../images/open_07.png"></span><a href="#">中国招商银行</a>
<ul></ul>
</li>
</ul>
</li>
</ul>
</div>

.bj{background: url(../../images/blue_07.png) no-repeat center center}
.bjunlock{background: url(../../images/blue_06.png) no-repeat center center}

var bj = $('.bj');
var addicon = $('.add');
$(addicon).hide();
$(bj).click(function(){
$(addicon).toggle();
$(this).toggleClass('bjunlock');//实现切换效果的js
});