Android dom方法でxmlを作成する

<?xml version="1.0" encoding="utf-8"?>
<classes>
	<group name="一年级" num="10">
		<person name="小明" age="7">
			<chinese>语文90</chinese>
			<english>英语80</english>
		</person>
	</group>
</classes>

// 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);
			InputStream fosStream = openFileInput(fileName);
			doc = docBuilder.parse(fosStream);

String[] fileNames = getFilesDir().list();