Java w3c dom的合并与格式化输出
遇到需要将几个W3C标准的Document文档简单合并，一个主文档，其他的文档并列按照顺序放在主文档的孩子节点上就行了。。。

public static String toString(Document doc) throws TransformerFactoryConfigurationError, TransformerException{ DOMSource source = new DOMSource(doc);         StringWriter writer = new StringWriter();         Result result = new StreamResult(writer);         Transformer transformer = TransformerFactory.newInstance().newTransformer();         transformer.setOutputProperty(OutputKeys.INDENT, "yes");         transformer.setOutputProperty(OutputKeys.CDATA_SECTION_ELEMENTS, "yes");       transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");        transformer.transform(source, result);         return (writer.getBuffer().toString());} 

transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");

原文出自：http://charyle.iteye.com/blog/1193846