.ftl ckeditor刷新时无法重新加载，无法获取改变后textarea的值

例子：

<script type="text/javascript" src="../ckeditor/ckeditor.js"></script>

 <textarea cols="80"  id="ed" name="ed" rows="10">ed</textarea >
    <script>
     var theCKEditor;
     if(CKEDITOR.instances[ed]){ //判断 ed是否已经被绑定
      CKEDITOR.remove(CKEDITOR.instances[ed]); //如果绑定了就解绑定
      }
      theCKEditor = CKEDITOR.replace('ed'); 
     
     function closeCKEditor(){  
     if(theCKEditor!=null)    {
       theCKEditor.destroy();    
       theCKEditor = null;
       theCKEditor = CKEDITOR.replace('ed');
       }
       }
    </script>
   <input type="button" class="btn btn-default" name="" value="保存"
      onclick="javascript:closeCKEditor();"/>