Android提高第七篇之XML解析与生成

**解析XML文件，Android 内置了三种解析方案。

SAX解析XML

1. person.xml:

view plain<?xml version="1.0" encoding="UTF-8"?>
<persons>
<person id="23">
<name>wjh</name>
<age>25</age>
</person>
<person id="20">
<name>wjh2</name>
<age>30</age>
</person>
</persons>

2. Service:

view plainpublic class XMLParserService {
public static List<Person> readXML(InputStream inStream) throws Exception {
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser saxParser = spf.newSAXParser(); // 创建解析器
// 设置解析器的相关特性，http://xml.org/sax/features/namespaces = true 表示开启命名空间特性
//saxParser.setProperty("http://xml.org/sax/features/namespaces", true);
XMLContentHandler handler = new XMLContentHandler();
saxParser.parse(inStream, handler);
inStream.close();
return handler.getPersons();
}

}

3. ContentHandler

view plainpublic class XMLContentHandler extends DefaultHandler {

private List<Person> persons;
private Person person;
private String preTag;

@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
if(preTag != null) {
String data = new String(ch, start, length);
if("name".equals(preTag)) {
person.setName(data);
} else if("age".equals(preTag)) {
person.setAge(Short.valueOf(data));
}
}
}

@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
if("person".equals(localName) && person != null) {
persons.add(person);
}
preTag = null;
}

@Override
public void startDocument() throws SAXException {
persons = new ArrayList<Person>();
}

@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
if("person".equals(localName)) {
person = new Person();
person.setId(Integer.parseInt(attributes.getValue(0)));
}
preTag = localName;
}

/**
* 返回解析出的 Person 对象集合
* @return
*/
public List<Person> getPersons() {
return persons;
}
}

DOM 解析上例的 XML 示例 ：

1. Service

view plainpublic class DOMService {

public static List<Person> readXML(InputStream inStream) throws Exception {
List<Person> persons = new ArrayList<Person>();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document dom = builder.parse(inStream);

Element root = dom.getDocumentElement();
NodeList personNodes = root.getElementsByTagName("person");

for(int i=0; i < personNodes.getLength(); i++) {
Person person = new Person();
Element personNode = (Element) personNodes.item(i);

person.setId(Integer.parseInt(personNode.getAttribute("id")));

NodeList personChildList = personNode.getChildNodes();
for(int j=0; j<personChildList.getLength(); j++) {
Node node = personChildList.item(j);
if(node.getNodeType() == Node.ELEMENT_NODE) {
Element element = (Element) node;
if("name".equals(element.getNodeName())) {
person.setName(element.getFirstChild().getNodeValue());
} else if ("age".equals(element.getNodeName())) {
person.setAge(Short.valueOf(element.getFirstChild().getNodeValue()));
}
}
}

persons.add(person);
}
return persons;
}
}
解析后返回解析的 Person 集合，任务完毕。

**Pull 解析上例的 XML 示例 （推荐）：
view plainpublic static List<Person> readXML(InputStream is) throws Exception {
List<Person> persons = null;
Person person = null;
XmlPullParser pullParser = Xml.newPullParser();
pullParser.setInput(is, "UTF-8");
int eventType = pullParser.getEventType(); // 触发第一个事件

while (eventType != XmlPullParser.END_DOCUMENT) { // 如果不为文档结束事件
switch (eventType) {
case XmlPullParser.START_DOCUMENT: // 文档开始事件
persons = new ArrayList<Person>();
break;
case XmlPullParser.START_TAG: // 标签开始事件
if ("person".equals(pullParser.getName())) {
int id = Integer.parseInt(pullParser.getAttributeValue(0));

person = new Person();
person.setId(id);
}
if (person != null) {
if ("name".equals(pullParser.getName())) { // 读取到 name 标签
person.setName(pullParser.nextText());
}
if ("age".equals(pullParser.getName())) { // 读取到 age 标签
person.setAge((Short.valueOf((pullParser.nextText()))));
}
}
break;
case XmlPullParser.END_TAG: // 标签结束事件
if ("person".equals(pullParser.getName())) {
persons.add(person);
person = null;
}
break;
}
eventType = pullParser.next();
}

return persons;
}

** Pull 解析器生成 XML 文件
view plainpublic static void save(List<Person> persons, OutputStream os) throws Exception {
XmlSerializer serializer = Xml.newSerializer();
serializer.setOutput(os, "UTF-8");
// 第二个参数：此 XML 是否可独立存在
serializer.startDocument("UTF-8", true);
// 第一个参数：命名空间，无则为null
serializer.startTag(null, "persons");

for(Person person : persons) {
serializer.startTag(null, "person");

serializer.attribute(null, "id", person.getId().toString());

serializer.startTag(null, "name");
serializer.text(person.getName());
serializer.endTag(null, "name");

serializer.startTag(null, "age");
serializer.text(person.getAge().toString());
serializer.endTag(null, "age");

serializer.endTag(null, "person");
}

serializer.endTag(null, "persons");
serializer.endDocument();
}