1.XML数据要点介绍
2.三种解析XML方法的比较
3.SAX解析XML数据
核心代码:
public class SaxHelper extends DefaultHandler {
private Person person;
private ArrayList<Person> persons;
//当前解析的元素标签
private String tagName = null;
/**
* 当读取到文档开始标志是触发,通常在这里完成一些初始化操作
* @throws SAXException
*/
@Override
public void startDocument() throws SAXException {
this.persons = new ArrayList<Person>();
Log.i("SAX", "读取到文档头,开始解析xml");
}
/**
* 读到一个开始标签时调用,第二个参数为标签名,最后一个参数为属性数组
* @param uri
* @param localName
* @param qName
* @param attributes
* @throws SAXException
*/
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
if (localName.equals("person")){
person = new Person();
person.setId(Integer.parseInt(attributes.getValue("id")));
Log.i("SAX", "开始处理person元素~");
}
this.tagName = localName;
}
/**
* 读到到内容,第一个参数为字符串内容,后面依次为起始位置与长度
* @param ch
* @param start
* @param length
* @throws SAXException
*/
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
//判断当前标签是否有效
if (this.tagName != null){
String data = new String(ch, start, length);
//读取标签中的内容
if (this.tagName.equals("name")){
this.person.setName(data);
Log.i("SAX", "处理name元素内容");
}else if (this.tagName.equals("age")){
this.person.setAge(Integer.parseInt(data));
Log.i("SAX", "处理age元素内容");
}
}
}
/**
* 处理元素结束时触发,这里将对象添加到结合中
* @param uri
* @param localName
* @param qName
* @throws SAXException
*/
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
if (localName.equals("person")){
this.persons.add(person);
person = null;
Log.i("SAX", "处理person元素结束~");
}
this.tagName = null;
}
/**
* 读取到文档结尾时触发,
* @throws SAXException
*/
@Override
public void endDocument() throws SAXException {
super.endDocument();
Log.i("SAX", "读取到文档尾,xml解析结束");
}
//获取persons集合
public ArrayList<Person> getPersons(){
return persons;
}
}
在MainActivity.java中写上写上这样一个方法,然后要解析XML的时候调用下
private ArrayList<Person> readxmlForSAX() throws Exception {
//获取文件资源建立输入流对象
InputStream is = getAssets().open("person1.xml");
//①创建XML解析处理器
SaxHelper ss = new SaxHelper();
//②得到SAX解析工厂
SAXParserFactory factory = SAXParserFactory.newInstance();
//③创建SAX解析器
SAXParser parser = factory.newSAXParser();
//④将xml解析处理器分配给解析器,对文档进行解析,将事件发送给处理器
parser.parse(is, ss);
is.close();
return ss.getPersons();
}
4.DOM解析XML数据
核心代码:
public class DomHelper {
public static ArrayList<Person> queryXML(Context mContent){
ArrayList<Person> persons = new ArrayList<Person>();
try {
//①获得DOM解析器的工厂示例:
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
//②从Dom工厂中获得dom解析器
DocumentBuilder builder = dbFactory.newDocumentBuilder();
//③把要解析的xml文件读入Dom解析器
Document document = builder.parse(mContent.getAssets().open("person2.xml"));
System.out.println("处理该文档的DomImplemention对象=" + document.getImplementation());
//④得到文档中名称为person的元素的结点列表
NodeList nodeList = document.getElementsByTagName("person");
//⑤遍历该集合,显示集合中的元素以及子元素的名字
for (int i = 0; i < nodeList.getLength(); i ++){
//先从Person元素开始解析
Element personElement = (Element)nodeList.item(i);
Person person = new Person();
person.setId(Integer.valueOf(personElement.getAttribute("id")));
//获取person下的name和age的Note集合
NodeList childList = personElement.getChildNodes();
for (int j = 0; j < childList.getLength(); j ++){
Node childNode = childList.item(j);
//判断子note类型是否为元素Note
if (childNode.getNodeType() == Node.ELEMENT_NODE){
Element childElement = (Element)childNode;
if ("name".equals(childElement.getNodeName())){
person.setName(childElement.getFirstChild().getNodeValue());
}else if("age".equals(childElement.getNodeName())){
person.setAge(Integer.valueOf(childElement.getFirstChild().getNodeValue()));
}
}
}
persons.add(person);
}
} catch (Exception e) {
e.printStackTrace();
}
return persons;
}
5.PULL解析XML数据
核心代码:
public static ArrayList<Person> getPersons(InputStream xml) throws Exception{
ArrayList<Person> persons = null;
Person person = null;
// 创建一个xml解析的工厂
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
// 获得xml解析类的引用
XmlPullParser parser = factory.newPullParser();
parser.setInput(xml, "UTF-8");
// 获得事件的类型
int eventType = parser.getEventType();
while (eventType != XmlPullParser.END_DOCUMENT){
switch (eventType){
case XmlPullParser.START_DOCUMENT:{
persons = new ArrayList<Person>();
break;
}
case XmlPullParser.START_TAG:{
if ("person".equals(parser.getName())){
person = new Person();
// 取出属性值
int id = Integer.parseInt(parser.getAttributeValue(0));
person.setId(id);
}else if("name".equals(parser.getName())){
// 获取该节点的内容
String name = parser.nextText();
person.setName(name);
}else if("age".equals(parser.getName())){
int age = Integer.parseInt(parser.nextText());
person.setAge(age);
}
break;
}
case XmlPullParser.END_TAG:{
if ("person".equals(parser.getName())){
persons.add(person);
person = null;
}
break;
}
}
eventType = parser.next();
}
return persons;
}
核心代码:
public static void save(List<Person> persons, OutputStream outputStream) throws Exception{
XmlSerializer serializer = Xml.newSerializer();
serializer.setOutput(outputStream, "UTF-8");
serializer.startDocument("UTF-8", true);
serializer.startTag(null, "persons");
for (Person person: persons) {
serializer.startTag(null, "person");
serializer.attribute(null, "id", person.getId() + "");
serializer.startTag(null, "name");
serializer.text(person.getName());
serializer.endTag(null, "name");
serializer.startTag(null, "age");
serializer.text(person.getAge() + "");
serializer.endTag(null, "age");
serializer.endTag(null, "person");
}
serializer.endTag(null, "persons");
serializer.endDocument();
outputStream.flush();
outputStream.close();
}
代码下载: XMLParseDemo.zip:下载 XMLParseDemo.zip