如果找到则搜索包含在xml中替换整个节点

My xml file:

我的xml文件:

<?xml version="1.0" encoding="utf-8"?>
<layout name="layout">
  <section name="Header">
    <placeholder name="headers" width="30" class="header">sam,pam</placeholder>
  </section>
  <section name="Content">
    <placeholder name="RightA" width="55">location</placeholder>
  </section>
</layout>
<?xml version="1.0" e