使用java从生成的xml文档中删除xml声明

String root = "RdbTunnels";
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.newDocument();
Element rootElement = document.createElement(root);
document.appendChild(rootElement);   

OutputFormat format = new OutputFormat(document);
format.setIndenting(true);


XMLSerializer serializer = new XMLSerializer(System.out,format);
serializer.serialize(document);

给出结果如下

<?xml version="1.0" encoding="UTF-8"?>
<RdbTunnels/>

但是我需要从输出中删除xml声明,该怎么做呢？