Android dom parses xml method

<?xml version="1.0" encoding="utf-8"?>
<classes>
	<group name="一年级" num="10">
		<person name="小明" age="7">
			<chinese>
				语文80
			</chinese>
			<english>
				英语89
			</english>
		</person>
		<person name="小强" age="8">
			<chinese>
				语文90
			</chinese>
			<english>
				英语99
			</english>
		</person>
	</group>
	<group name="二年级" num="20">
		<person name="小文" age="8">
			<chinese>
				语文85
			</chinese>
			<english>
				英语95
			</english>
		</person>
		<person name="小中" age="9">
			<chinese>
				语文80
			</chinese>
			<english>
				英语90
			</english>
		</person>
	</group>
</classes>

/**
 * 用dom方式 解析xml 文件
 * @param fileName
 */
	private String domXmlParse(String fileName) {
		String str="";
		// xml文档创建工厂
		DocumentBuilderFactory docFactory = DocumentBuilderFactory
				.newInstance();
		// xml文档创建实例
		DocumentBuilder docBuilder;
		// xml文档
		Document doc = null;
		InputStream inStream = null;
		try {
			docBuilder = docFactory.newDocumentBuilder();
			// 从assets文件夹下获取文件 转换成输入流
			inStream = this.getResources().getAssets().open(fileName);
			doc = docBuilder.parse(inStream);
			// 获取xml跟元素
			Element rootEle = doc.getDocumentElement();
			// 二级父元素的list列表
			NodeList groupNode = rootEle.getElementsByTagName("group");
			// NodeList childNode = rootEle.getElementsByTagName("person");
			// 遍历Classe下所有的group
			for (int i = 0; i < groupNode.getLength(); i++) {

				Element groupEle = (Element) groupNode.item(i);
				String groupName = groupEle.getAttribute("name");
				String num = groupEle.getAttribute("num");
				str =str+"name ="+groupName+" num = "+num+"\n";
				
				Log.e("xml", "name = " + groupName + "  num = " + num);

//				NodeList personNode = groupNode.item(i).getChildNodes();
				NodeList personNode = groupEle.getElementsByTagName("person");
				// 遍历group下的所有person
				for (int j = 0; j < personNode.getLength(); j++) {
					Element personEle = (Element) personNode.item(j);
					String name = personEle.getAttribute("name");
					String age = personEle.getAttribute("age");
					str =str+"personName ="+name+" personAge = "+age+"\n";
					
					Log.e("xml", "name = " + name + "   age = " + age);

					Element chineseEle = (Element) personEle
							.getElementsByTagName("chinese").item(0);
					Element englistEle = (Element) personEle
							.getElementsByTagName("english").item(0);
					String chinese = chineseEle.getFirstChild().getNodeValue();
					String english = englistEle.getFirstChild().getNodeValue();
					str =str+"chinese = "+chinese+" english = "+english+"\n";
					
					Log.e("xml", "chinese = " + chinese + "   english = "
							+ english);
				}
			}

		} catch (ParserConfigurationException e1) {
			e1.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		}
		return str;
	}