用Stax方式处理xml

1.读取xml文件，首先用类加载器加载项目目录下的xml文件，从XMLInputFactory创建我所需要的XMLStreamReader，即得到了xml文件。根据XMLStreamConstant

属性值，就可以操作所得到的xml文件内容，详情看以下代码。

public class TestStax {
    public static void main(String[] args) {
        //基于光标式的
//        new TestStax().baseStax();
//        new TestStax().baseStax_01();
        //基于迭代模型的
//       new TestStax().baseStax_02();
　　　　　//基于过滤器的　
　　　　　new TestStax().baseStax_03();　
    }
    public void baseStax(){
        XMLInputFactory xif = XMLInputFactory.newInstance();
        InputStream is = null;
        XMLStreamReader xsr = null;
        try {
            //第一种加载文件方式，此文件在根目录下
            is = TestStax.class.getClassLoader().getResourceAsStream("menu.xml");
            xsr = xif.createXMLStreamReader(is);
            while(xsr.hasNext()){
                int type = xsr.next();
                System.out.println(type);
                if(type == XMLStreamConstants.START_ELEMENT){
                    System.out.println(xsr.getName());
                }else if(type == XMLStreamConstants.CHARACTERS){
                    System.out.println(xsr.getText().trim());
                }else if(type == XMLStreamConstants.END_ELEMENT){
                    System.out.println("/" + xsr.getName());
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(is != null){
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            }
        }
    }
    public void baseStax_01(){
        XMLInputFactory xif = XMLInputFactory.newInstance();
        InputStream is = null;
        XMLStreamReader xmlsr = null;
        try {
            //另一种加载文件方式
            is = new FileInputStream(System.getProperty("java.class.path") + File.separator + "menu.xml");
            xmlsr = xif.createXMLStreamReader(is);
            while(xmlsr.hasNext()){
                int type = xmlsr.next();
                //XMLStreamConstants.START_ELEMENT=1
                if(type == 1){
                if("name".equals(xmlsr.getName().toString())){
                    System.out.print(xmlsr.getElementText() + ":");
                }else if("price".equals(xmlsr.getName().toString())){
                    System.out.println(xmlsr.getElementText());
                }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    public void baseStax_02(){
        XMLInputFactory xif = XMLInputFactory.newInstance();
        InputStream is = null;
        is = TestStax.class.getClassLoader().getResourceAsStream("menu.xml");
        try {
            XMLEventReader xmler = xif.createXMLEventReader(is);
            while(xmler.hasNext()){
                XMLEvent xmle = xmler.nextEvent();
                if(xmle.isStartElement()){
                    String name = xmle.asStartElement().getName().toString();
                    if("name".equals(name)){
                        System.out.print(xmler.getElementText() + ":");
                    }else if("price".equals(name)){
                        System.out.println(xmler.getElementText());
                    }
                }
            }
        } catch (XMLStreamException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
　　public void baseStax_03(){
  XMLInputFactory xif = XMLInputFactory.newFactory();
  InputStream is = TestStax.class.getClassLoader().getResourceAsStream("menu.xml");
  XMLEventReader xmler = null;
  try {
   xmler = xif.createFilteredReader(xif.createXMLEventReader(is), new EventFilter() {
    @Override
    public boolean accept(XMLEvent event) {
     if(event.isStartElement()){
      String name = event.asStartElement().getName().toString();
      if("name".equals(name) || "price".equals(name)){
       return true;
      }
     }
     return false;
    }
   } );
  } catch (XMLStreamException e) {
   e.printStackTrace();
  }
  while(xmler.hasNext()){ 
   try {
    XMLEvent xmle = xmler.nextEvent();
    if(xmle.isStartElement()){
     String nm = xmle.asStartElement().getName().toString();
     if("name".equals(nm)){
      System.out.print(xmler.getElementText() + ":");
     }else if("price".equals(nm)){
      System.out.println(xmler.getElementText());
     }
    }
   } catch (XMLStreamException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
 }
}

下面是我说是用的xml，在w3cSchool里弄的xml文件，也可以自己建一个xml文件

<?xml version="1.0" encoding="UTF-8"?>

 <breakfast_menu>
 <food ceshi="test">
  <name>Belgian Waffles</name>
  <price>$5.95</price>
  <description>two of our famous Belgian Waffles with plenty of real maple syrup</description>
  <calories>650</calories>
  </food>
 <food ceshi="test">
  <name>Strawberry Belgian Waffles</name>
  <price>$7.95</price>
  <description>light Belgian waffles covered with strawberries and whipped cream</description>
  <calories>900</calories>
  </food>
 <food>
  <name>Berry-Berry Belgian Waffles</name>
  <price>$8.95</price>
  <description>light Belgian waffles covered with an assortment of fresh berries and whipped cream</description>
  <calories>900</calories>
  </food>
 <food>
  <name>French Toast</name>
  <price>$4.50</price>
  <description>thick slices made from our homemade sourdough bread</description>
  <calories>600</calories>
  </food>
 <food>
  <name>Homestyle Breakfast</name>
  <price>$6.95</price>
  <description>two eggs, bacon or sausage, toast, and our ever-popular hash browns</description>
  <calories>950</calories>
  </food>
  </breakfast_menu>

3.基于Xpath处理xml

     //基于Xpath
     public void baseStax_04(){
         InputStream is = null;
         is = TestStax.class.getClassLoader().getResourceAsStream("menu.xml");
         XPathFactory xpf = XPathFactory.newInstance();
         XPath xp = xpf.newXPath();
         try {
             //创建文档对象
             DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
             //创建文档
             Document doc = db.parse(is);
             NodeList nl = (NodeList)xp.evaluate("//food[@ceshi='test']", doc,XPathConstants.NODESET);
 //            for(int i=0;i<nl.getLength();i++){
 //                Element ele = (Element)nl.item(i);
 //                String value = ele.getElementsByTagName("name").item(0).getTextContent();
 //                System.out.println(value);
 //            }
             //当不把node转化为element时
             for(int j=0;j<nl.getLength();j++){
                 NodeList nodelist = nl.item(j).getChildNodes();
                 for(int p=0;p<nodelist.getLength();p++){
                     Node nodechild = nodelist.item(p);
                     if(nodechild.getNodeName() != "#text"){
                         System.out.println(nodechild.getNodeName() + ":" + nodechild.getTextContent());
                     }
                 }
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

4.修改xml,用XPath计算得到查找的位置，修改后用Transformer进行替换原文件

 public void update_xml(){
         XPath xpath = XPathFactory.newInstance().newXPath();
         InputStream is = TestStax.class.getClassLoader().getResourceAsStream("menu.xml");
         Document doc= null;
         try {
             doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(is);
             NodeList nodelist = (NodeList)xpath.evaluate("//food[name='Belgian']", doc,XPathConstants.NODESET );
             Element element = (Element)nodelist.item(0);
             Element ele = (Element)element.getElementsByTagName("price").item(0);
             System.out.println(ele.getTextContent());
             ele.setTextContent("12121");
             Transformer transformer = TransformerFactory.newInstance().newTransformer();
             transformer.setOutputProperty(OutputKeys.ENCODING,"UTF-8");
             Result result = new StreamResult(System.out);
             transformer.transform(new DOMSource(doc), result);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

5.以XMLStreamWriter的方式写入xml

 public void writeXml(){
         try {
             XMLStreamWriter xmlsw = XMLOutputFactory.newFactory().createXMLStreamWriter(System.out);
             xmlsw.writeStartDocument("UTF-8", "1.0");
             xmlsw.writeEndDocument();
             String ns = "http://xiaoqiaolv";
             xmlsw.writeStartElement("ns","student",ns);
             xmlsw.writeStartElement("name");
             xmlsw.writeAttribute("realname","zhangsan");
             xmlsw.writeCharacters("text");
             xmlsw.writeEndElement();
             xmlsw.writeEndElement();
             xmlsw.flush();
             xmlsw.close();
         } catch (Exception e) {
             e.printStackTrace();
         }
     }