XML的解析DOM

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

[java] view
plaincopyprint?

/** 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

[java] view
plaincopyprint?

/** 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

[java] view
plaincopyprint?

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";

}

}