<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE students [
 <!ELEMENT students (student+)>
 <!ELEMENT student (name,course,score)>
 <!ATTLIST student id CDATA #REQUIRED>
 <!ELEMENT name (#PCDATA)>
 <!ELEMENT course (#PCDATA)>
 <!ELEMENT score (#PCDATA)>
]>
<students>
 <student id="11"> 
  <name>张三</name> 
  <course>JavaSE</course>
  <score>100</score>
 </student>
 <student id="22">  
  <name>李四</name>
  <course>Oracle</course>
  <score>98</score>
 </student> 
</students>

public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {
  //1.创建DOM解析器工厂
  DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
  //2.由DOM解析器工厂创建DOM解析器
  DocumentBuilder db = dbf.newDocumentBuilder();
  //3.由DOM解析器解析文档，生成DOM树
  Document doc = db.parse("scores.xml");
  //4.解析DOM树，获取文档内容（元素 属性 文本）
  //4.1获取根元素scores
  NodeList scoresList = doc.getChildNodes();
  Node scoresNode = scoresList.item(1);
  System.out.println(scoresList.getLength());
  //4.2获取scores中所有的子元素student
  NodeList studentList = scoresNode.getChildNodes();
  System.out.println(studentList.getLength());
  //4.3对每个student进行处理
  for(int i=0;i<studentList.getLength();i++){
   Node stuNode = studentList.item(i);
   //System.out.println(stuNode.getNodeType());
   //输出元素的属性 id
   if(stuNode.getNodeType()==Node.ELEMENT_NODE){
    Element elem =(Element)stuNode;
    String id= elem.getAttribute("id");
    System.out.println("id------>"+id);
   }
   //输出元素的子元素 name course score
   NodeList ncsList = stuNode.getChildNodes();
   //System.out.println(ncsList.getLength() );
   for(int j=0;j<ncsList.getLength();j++){
    Node ncs = ncsList.item(j);
    if(ncs.getNodeType() == Node.ELEMENT_NODE){
      String name = ncs.getNodeName();
      //String value = ncs.getFirstChild().getNodeValue();//文本是元素的子节点，所以要getFirstChild
      String value = ncs.getTextContent();
      System.out.println(name+"----->"+value);
    }
   }
   System.out.println();
  }
 }

 public static void main(String[] args) throws DocumentException {
  //使用dom4j解析scores2.xml,生成dom树
  SAXReader reader = new SAXReader();
  Document doc = reader.read(new File("scores.xml"));  
  //得到根节点：students
  Element root = doc.getRootElement();  
  //得到students的所有子节点：student
  Iterator<Element> it = root.elementIterator(); 
  //处理每个student
  while(it.hasNext()){
   //得到每个学生
   Element stuElem =it.next();
   //System.out.println(stuElem);
   //输出学生的属性：id
   List<Attribute> attrList = stuElem.attributes();
   for(Attribute attr :attrList){
    String name = attr.getName();
    String value = attr.getValue();
    System.out.println(name+"----->"+value);
   }
   //输出学生的子元素：name，course，score
   Iterator <Element>it2 = stuElem.elementIterator();
   while(it2.hasNext()){
    Element elem = it2.next();
    String name = elem.getName();
    String text = elem.getText();
    System.out.println(name+"----->"+text);
   }
   System.out.println();
  } 
 }

public class PropertiesUtil {
 private static PropertiesUtil manager = null;
 private static Object managerLock = new Object();
 private Object propertiesLock = new Object();
 private static String DATABASE_CONFIG_FILE = "/path.properties";
 private Properties properties = null;
 public static PropertiesUtil getInstance() {
  if (manager == null) {
   synchronized (managerLock) {
    if (manager == null) {
     manager = new PropertiesUtil();
    }
   }
  }
  return manager;
 }
 private PropertiesUtil() {
 }
 public static String getProperty(String name) {
  return getInstance()._getProperty(name);
 }
 private String _getProperty(String name) {
  initProperty();
  String property = properties.getProperty(name);
  if (property == null) {
   return "";
  } else {
   return property.trim();
  }
 }
 public static Enumeration<?> propertyNames() {
  return getInstance()._propertyNames();
 }
 private Enumeration<?> _propertyNames() {
  initProperty();
  return properties.propertyNames();
 }
 private void initProperty() {
  if (properties == null) {
   synchronized (propertiesLock) {
    if (properties == null) {
     loadProperties();
    }
   }
  }
 }
 private void loadProperties() {
  properties = new Properties();
  InputStream in = null;
  try {
   in = getClass().getResourceAsStream(DATABASE_CONFIG_FILE);
   properties.load(in);
  } catch (Exception e) {
   System.err
     .println("Error reading conf properties in PropertiesUtil.loadProps() "
       + e);
   e.printStackTrace();
  } finally {
   try {
    in.close();
   } catch (Exception e) {
   }
  }
 }
 /**
  * 提供配置文件路径
  * 
  * @param filePath
  * @return
  */
 public Properties loadProperties(String filePath) {
  Properties properties = new Properties();
  InputStream in = null;
  try {
   in = getClass().getResourceAsStream(filePath);
   properties.load(in);
  } catch (Exception e) {
   System.err
     .println("Error reading conf properties in PropertiesUtil.loadProperties() "
       + e);
   e.printStackTrace();
  } finally {
   try {
    in.close();
   } catch (Exception e) {
   }
  }
  return properties;
 }
}