Android 创建与解析XML（二）—— Dom方式

1. Dom概述

Dom方式创建XML，应用了标准xml构造器 javax.xml.parsers.DocumentBuilder 来创建 XML 文档，需要导入以下内容

javax.xml.parsers

javax.xml.parsers.DocumentBuilder 

javax.xml.parsers.DocumentBuilderFactory 

javax.xml.parsers.ParserConfigurationException;

javax.xml.transform

javax.xml.transform.TransformerFactory 

javax.xml.transform.Transformer 

javax.xml.transform.dom.DOMSource 

javax.xml.transform.stream.StreamResult 

javax.xml.transform.OutputKeys;

javax.xml.transform.TransformerFactoryConfigurationError;

javax.xml.transform.TransformerConfigurationException;

javax.xml.transform.TransformerException;

org.w3c.dom 

org.w3c.dom.Document;

org.w3c.dom.Element;

org.w3c.dom.Node;

org.w3c.dom.DOMException;

org.w3c.dom.NodeList;

org.xml.sax.SAXException;

sdk源码查看路径（google code）

创建和解析xml的效果图：

2、Dom 创建 XML

Dom，借助 javax.xml.parsers.DocumentBuilder，可以创建 org.w3c.dom.Document 对象。

使用来自 DocumentBuilderFactory 的 DocumentBuilder 对象在 Android 设备上创建与解析 XML 文档。您将使用 XML pull 解析器的扩展来解析 XML 文档。

Code

 /** Dom方式，创建 XML  */
 public String domCreateXML() {
     String xmlWriter = null;

     Person []persons = new Person[3];       // 创建节点Person对象
     persons[0] = new Person(1, "sunboy_2050", "http://blog.csdn.net/sunboy_2050");
     persons[1] = new Person(2, "baidu", "http://www.baidu.com");
     persons[2] = new Person(3, "google", "http://www.google.com");

     try {
         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = factory.newDocumentBuilder();
         Document doc = builder.newDocument();

         Element eleRoot = doc.createElement("root");
         eleRoot.setAttribute("author", "homer");
         eleRoot.setAttribute("date", "2012-04-26");
         doc.appendChild(eleRoot);

         int personsLen = persons.length;
         for(int i=0; i<personsLen; i++) {
             Element elePerson = doc.createElement("person");
             eleRoot.appendChild(elePerson);

             Element eleId = doc.createElement("id");
             Node nodeId = doc.createTextNode(persons[i].getId() + "");
             eleId.appendChild(nodeId);
             elePerson.appendChild(eleId);

             Element eleName = doc.createElement("name");
             Node nodeName = doc.createTextNode(persons[i].getName());
             eleName.appendChild(nodeName);
             elePerson.appendChild(eleName);

             Element eleBlog = doc.createElement("blog");
             Node nodeBlog = doc.createTextNode(persons[i].getBlog());
             eleBlog.appendChild(nodeBlog);
             elePerson.appendChild(eleBlog);
         }


         Properties properties = new Properties();
         properties.setProperty(OutputKeys.INDENT, "yes");
         properties.setProperty(OutputKeys.MEDIA_TYPE, "xml");
         properties.setProperty(OutputKeys.VERSION, "1.0");
         properties.setProperty(OutputKeys.ENCODING, "utf-8");
         properties.setProperty(OutputKeys.METHOD, "xml");
         properties.setProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

         TransformerFactory transformerFactory = TransformerFactory.newInstance();
         Transformer transformer = transformerFactory.newTransformer();
         transformer.setOutputProperties(properties);

         DOMSource domSource = new DOMSource(doc.getDocumentElement());
         OutputStream output = new ByteArrayOutputStream();
         StreamResult result = new StreamResult(output);
         transformer.transform(domSource, result);

         xmlWriter = output.toString();

     } catch (ParserConfigurationException e) {      // factory.newDocumentBuilder
         e.printStackTrace();
     } catch (DOMException e) {                      // doc.createElement
         e.printStackTrace();
     } catch (TransformerFactoryConfigurationError e) {      // TransformerFactory.newInstance
         e.printStackTrace();
     } catch (TransformerConfigurationException e) {     // transformerFactory.newTransformer
         e.printStackTrace();
     } catch (TransformerException e) {              // transformer.transform
         e.printStackTrace();
     } catch (Exception e) {
         e.printStackTrace();
     }

     savedXML(fileName, xmlWriter.toString());

     return xmlWriter.toString();
 }

运行结果：

3、Dom 解析 XML

Dom方式，解析XML是创建XML的逆过程，主要用到了builder.parse(is)进行解析，然后通过Tag、NodeList、Element、childNotes等得到Element和Node属性或值。

Code

 /** Dom方式，解析 XML  */
 public String domResolveXML() {
     StringWriter xmlWriter = new StringWriter();

     InputStream is= readXML(fileName);
     try {
         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = factory.newDocumentBuilder();
         Document doc = builder.parse(is);

         doc.getDocumentElement().normalize();
         NodeList nlRoot = doc.getElementsByTagName("root");
         Element eleRoot = (Element)nlRoot.item(0);
         String attrAuthor = eleRoot.getAttribute("author");
         String attrDate = eleRoot.getAttribute("date");
         xmlWriter.append("root").append("\t\t");
         xmlWriter.append(attrAuthor).append("\t");
         xmlWriter.append(attrDate).append("\n");

         NodeList nlPerson = eleRoot.getElementsByTagName("person");
         int personsLen = nlPerson.getLength();
         Person []persons = new Person[personsLen];
         for(int i=0; i<personsLen; i++) {
             Element elePerson = (Element) nlPerson.item(i);     // person节点
             Person person = new Person();                       // 创建Person对象

             NodeList nlId = elePerson.getElementsByTagName("id");
             Element eleId = (Element)nlId.item(0);
             String id = eleId.getChildNodes().item(0).getNodeValue();
             person.setId(Integer.parseInt(id));

             NodeList nlName = elePerson.getElementsByTagName("name");
             Element eleName = (Element)nlName.item(0);
             String name = eleName.getChildNodes().item(0).getNodeValue();
             person.setName(name);

             NodeList nlBlog = elePerson.getElementsByTagName("blog");
             Element eleBlog = (Element)nlBlog.item(0);
             String blog = eleBlog.getChildNodes().item(0).getNodeValue();
             person.setBlog(blog);

             xmlWriter.append(person.toString()).append("\n");
             persons[i] = person;
         }

     } catch (ParserConfigurationException e) {      // factory.newDocumentBuilder
         e.printStackTrace();
     } catch (SAXException e) {      // builder.parse
         e.printStackTrace();
     } catch (IOException e) {       // builder.parse
         e.printStackTrace();
     } catch (Exception e) {
         e.printStackTrace();
     }

     return xmlWriter.toString();
 }

运行结果：

4、Person类

Person类，是创建xml的单位实例，基于Java面向对象定义的一个类

 public class Person {
     private int id;
     private String name;
     private String blog;

     public Person() {
         this.id = -1;
         this.name = "";
         this.blog = "";
     }

     public Person(int id, String name, String blog) {
         this.id = id;
         this.name = name;
         this.blog = blog;
     }

     public Person(Person person) {
         this.id = person.id;
         this.name = person.name;
         this.blog = person.blog;
     }

     public Person getPerson(){
         return this;
     }

     public void setId(int id) {
         this.id = id;
     }

     public int getId(){
         return this.id;
     }

     public void setName(String name) {
         this.name = name;
     }

     public String getName() {
         return this.name;
     }

     public void setBlog(String blog) {
         this.blog = blog;
     }

     public String getBlog() {
         return this.blog;
     }

     public String toString() {
         return "Person \nid = " + id + "\nname = " + name + "\nblog = " + blog + "\n";
     }
 }