JAXB与Stax

import javax.xml.bind.annotation.XmlRootElement; 
 
@XmlRootElement 
public class Student { 
    private int id; 
    private String name; 
    private int age; 
    private Classroom classroom; 
}

java转xml
JAXBContext ctx = JAXBContext.newInstance(Student.class); 
Marshaller marshaller = ctx.createMarshaller(); 
Student stu = new Student(1,"张三",21,new Classroom(1,"10计算机应用技术",2010)); 
marshaller.marshal(stu, System.out); 

xml转java
String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?><student><age>21</age><classroom><grade>2010</grade><id>1</id><name>10计算机应用技术</name></classroom><id>1</id><name>张三</name></student>"; 
JAXBContext ctx = JAXBContext.newInstance(Student.class); 
Unmarshaller um = ctx.createUnmarshaller(); 
Student stu = (Student)um.unmarshal(new StringReader(xml)); 


Stax:待处理的的xml文件
XMLInputFactory factory = XMLInputFactory.newInstance(); 
InputStream is =  TestStax.class.getClassLoader().getResourceAsStream("books.xml"); 
XMLStreamReader reader = factory.createXMLStreamReader(is); 
while(reader.hasNext()) { 
        int type = reader.next(); 
        if(type==XMLStreamConstants.START_ELEMENT) { 
            String name = reader.getName().toString(); 
            if(name.equals("book")) { 
                System.out.println(reader.getAttributeName(0)+":"+reader.getAttributeValue(0)); 
            } 
        } 
} 

XMLInputFactory factory = XMLInputFactory.newInstance(); 
InputStream is =  TestStax.class.getClassLoader().getResourceAsStream("books.xml"); 
//基于迭代模型的操作方<br> XMLEventReader reader = factory.createXMLEventReader(is); 
 
while(reader.hasNext()) { 
    //通过XMLEvent来获取是否是某种节点类型 
    XMLEvent event = reader.nextEvent(); 
    if(event.isStartElement()) { 
        //通过event.asxxx转换节点 
        String name = event.asStartElement().getName().toString(); 
        if(name.equals("title")) { 
            System.out.print(reader.getElementText()+":"); 
        } 
        if(name.equals("price")) { 
            System.out.print(reader.getElementText()+"\n"); 
        } 
    } 
} 

基于XPATH的处理

InputStream is = TestStax.class.getClassLoader().getResourceAsStream("books.xml"); 
//创建文档处理对象 
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder(); 
//通过DocumentBuilder创建doc的文档对象 
Document doc = db.parse(is); 
//创建XPath 
XPath xpath = XPathFactory.newInstance().newXPath(); 
//第一个参数就是xpath,第二参数就是文档 
NodeList list = (NodeList)xpath.evaluate("//book[@category='WEB']", doc,XPathConstants.NODESET); 
for(int i=0;i<list.getLength();i++) { 
    //遍历输出相应的结果 
    Element e = (Element)list.item(i); 
    System.out.println(e.getElementsByTagName("title").item(0).getTextContent()); 
}