如果是简单或者标准格式的xml，可以使用xstream，之前映射成一个对象然后去修改操作，很简单。

但是如果是负杂的，而且有可能xml的节点内容不一样，该怎么做呢？

一下是我的一种解决方法，当然可以利用其他的jar包如dom4j等，应该更简单一些

StringReader sr = new StringReader(strXml);   
		InputSource is = new InputSource(sr);   
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();   
		DocumentBuilder builder=factory.newDocumentBuilder();    
		Document doc = builder.parse(is);
		NodeList list = doc.getElementsByTagName("extract4DB");
		for (int i = 0; i < list.getLength(); i++) {
			Element ele = (Element) list.item(i);
			String brandName = ele.getAttribute("name");
			if(brandName.equals("ts1")){
				NodeList list1 = ele.getElementsByTagName("datasourceNames");
				Element ele1 = (Element) list1.item(0);
				String[] s = ele1.getTextContent().split(";");
				ele1.setTextContent(s[0]+"_standby;");
				System.out.println(ele1.getTextContent());
			}
		}
		
		TransformerFactory  tf  =  TransformerFactory.newInstance();    
		Transformer t = tf.newTransformer();    
		t.setOutputProperty("encoding","utf-8");  
		ByteArrayOutputStream  bos  =  new  ByteArrayOutputStream();   
		t.transform(new DOMSource(doc),new StreamResult(bos));    
		String xmlchange = bos.toString();  
		System.out.println(xmlchange);

strXml：是附件中的字符串