Android创建与解析XML（二）——详解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;

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。

/** 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://www.jb51.net/");
  persons[1] = new Person(2, "baidu", "http://wwwbaiducom");
  persons[2] = new Person(3, "google", "http://wwwgooglecom"); 

  try {
    DocumentBuilderFactory factory = DocumentBuilderFactorynewInstance();
    DocumentBuilder builder = factorynewDocumentBuilder();
    Document doc = buildernewDocument(); 

    Element eleRoot = doccreateElement("root");
    eleRootsetAttribute("author", "homer");
    eleRootsetAttribute("date", "2012-04-26");
    docappendChild(eleRoot); 

    int personsLen = personslength;
    for(int i=0; i<personsLen; i++) {
      Element elePerson = doccreateElement("person");
      eleRootappendChild(elePerson); 

      Element eleId = doccreateElement("id");
      Node nodeId = doccreateTextNode(persons[i]getId() + "");
      eleIdappendChild(nodeId);
      elePersonappendChild(eleId); 

      Element eleName = doccreateElement("name");
      Node nodeName = doccreateTextNode(persons[i]getName());
      eleNameappendChild(nodeName);
      elePersonappendChild(eleName); 

      Element eleBlog = doccreateElement("blog");
      Node nodeBlog = doccreateTextNode(persons[i]getBlog());
      eleBlogappendChild(nodeBlog);
      elePersonappendChild(eleBlog);
    } 

    Properties properties = new Properties();
    propertiessetProperty(OutputKeysINDENT, "yes");
    propertiessetProperty(OutputKeysMEDIA_TYPE, "xml");
    propertiessetProperty(OutputKeysVERSION, "0");
    propertiessetProperty(OutputKeysENCODING, "utf-8");
    propertiessetProperty(OutputKeysMETHOD, "xml");
    propertiessetProperty(OutputKeysOMIT_XML_DECLARATION, "yes"); 

    TransformerFactory transformerFactory = TransformerFactorynewInstance();
    Transformer transformer = transformerFactorynewTransformer();
    transformersetOutputProperties(properties); 

    DOMSource domSource = new DOMSource(docgetDocumentElement());
    OutputStream output = new ByteArrayOutputStream();
    StreamResult result = new StreamResult(output);
    transformertransform(domSource, result); 

    xmlWriter = outputtoString(); 

  } catch (ParserConfigurationException e) {   // factorynewDocumentBuilder
    eprintStackTrace();
  } catch (DOMException e) {           // doccreateElement
    eprintStackTrace();
  } catch (TransformerFactoryConfigurationError e) {   // TransformerFactorynewInstance
    eprintStackTrace();
  } catch (TransformerConfigurationException e) {   // transformerFactorynewTransformer
    eprintStackTrace();
  } catch (TransformerException e) {       // transformertransform
    eprintStackTrace();
  } catch (Exception e) {
    eprintStackTrace();
  } 

  savedXML(fileName, xmlWritertoString()); 

  return xmlWritertoString();
}

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。

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

  InputStream is= readXML(fileName);
  try {
    DocumentBuilderFactory factory = DocumentBuilderFactorynewInstance();
    DocumentBuilder builder = factorynewDocumentBuilder();
    Document doc = builderparse(is); 

    docgetDocumentElement()normalize();
    NodeList nlRoot = docgetElementsByTagName("root");
    Element eleRoot = (Element)nlRootitem(0);
    String attrAuthor = eleRootgetAttribute("author");
    String attrDate = eleRootgetAttribute("date");
    xmlWriterappend("root")append("\t\t");
    xmlWriterappend(attrAuthor)append("\t");
    xmlWriterappend(attrDate)append("\n"); 

    NodeList nlPerson = eleRootgetElementsByTagName("person");
    int personsLen = nlPersongetLength();
    Person []persons = new Person[personsLen];
    for(int i=0; i<personsLen; i++) {
      Element elePerson = (Element) nlPersonitem(i);   // person节点
      Person person = new Person();            // 创建Person对象 

      NodeList nlId = elePersongetElementsByTagName("id");
      Element eleId = (Element)nlIditem(0);
      String id = eleIdgetChildNodes()item(0)getNodeValue();
      personsetId(IntegerparseInt(id)); 

      NodeList nlName = elePersongetElementsByTagName("name");
      Element eleName = (Element)nlNameitem(0);
      String name = eleNamegetChildNodes()item(0)getNodeValue();
      personsetName(name); 

      NodeList nlBlog = elePersongetElementsByTagName("blog");
      Element eleBlog = (Element)nlBlogitem(0);
      String blog = eleBloggetChildNodes()item(0)getNodeValue();
      personsetBlog(blog); 

      xmlWriterappend(persontoString())append("\n");
      persons[i] = person;
    } 

  } catch (ParserConfigurationException e) {   // factorynewDocumentBuilder
    eprintStackTrace();
  } catch (SAXException e) {   // builderparse
    eprintStackTrace();
  } catch (IOException e) {    // builderparse
    eprintStackTrace();
  } catch (Exception e) {
    eprintStackTrace();
  } 

  return xmlWritertoString();
}

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() {
    thisid = -1;
    thisname = "";
    thisblog = "";
  } 

  public Person(int id, String name, String blog) {
    thisid = id;
    thisname = name;
    thisblog = blog;
  } 

  public Person(Person person) {
    thisid = personid;
    thisname = personname;
    thisblog = personblog;
  } 

  public Person getPerson(){
    return this;
  } 

  public void setId(int id) {
    thisid = id;
  } 

  public int getId(){
    return thisid;
  } 

  public void setName(String name) {
    thisname = name;
  } 

  public String getName() {
    return thisname;
  } 

  public void setBlog(String blog) {
    thisblog = blog;
  } 

  public String getBlog() {
    return thisblog;
  } 

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

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