运用java解析XML
使用java解析XML
Java本身提供了三种API进行XML文本的解析。
1.DOM：DOM方式解析XML文本时，先分析整个XML，形成XML的DOM树，然后节点列表的方式遍历它。
package xmlHandler;
import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
import org.xml.sax.SAXException;
public class DOMParserXml {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
DOMParserXml domparser=new DOMParserXml();
domparser.domParserForXML(System.getProperty("user.dir")+"/person.xml");
domparser.XPathGetValue(System.getProperty("user.dir")+"/person.xml");
}
// DOM解析器生成tree，解析过程也必须严格按照tree结构写成循环解析
public void domParserForXML(String xmlPath) {
Person person = new Person();// 用于存放解析出的值
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();// 创建XML的DOM工厂
try {
DocumentBuilder builder = factory.newDocumentBuilder();
File xmlFile = new File(xmlPath);// 可以用InputStream、URL、File来设置XML来源
Document doc = builder.parse(xmlFile);// 读入文档,这是一个接口
Element root = doc.getDocumentElement();// 获取根节点
System.out.println("根节点名称：" + root.getTagName());
NodeList children = root.getChildNodes();// 这里的child可以使文本、子元素、其他节点
for (int i = 0; i < children.getLength(); i++) {
Node child = children.item(i);
//使用语句factory.setIgnoringElementContentWhitespace(true);//过滤空白字符，就不需要判断类型了。
if (child instanceof Element) {// 解析器将标签之间的空格也认为是子元素，用instanceof过滤它们
Element childElement = (Element) child;
System.out.print("\t子节点名称" + childElement.getTagName());
System.out.println("\t属性值："
+ childElement.getAttribute("sex"));
//可以通过getAttributes方法获取所有属性值的键值对。
person.setSex(childElement.getAttribute("sex"));
NodeList grandsons = childElement.getChildNodes();
for (int j = 0; j < grandsons.getLength(); j++) {
Node grandson = grandsons.item(j);
if (grandson instanceof Element) {
Element grandElement = (Element) grandson;
System.out.print("\t\t孙节点名称:"
+ grandElement.getTagName());
Text textNode = (Text) grandElement.getFirstChild();
System.out.println("\t孙节点文本值:"
+ textNode.getData().trim());
if (grandElement.getTagName().equals("name")) {
person.setName(textNode.getData().trim());
}
if (grandElement.getTagName().equals("description")) {
person
.setDescription(textNode.getData()
.trim());
}
}
}
}
}
} catch (ParserConfigurationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}// 创建解析器
catch (SAXException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("解析结果：：：" + person.toString());
}
public void XPathGetValue(String xmlFilePath){
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();// 创建XML的DOM工厂
try {
DocumentBuilder builder = factory.newDocumentBuilder();
File file=new File(xmlFilePath);
Document doc=builder.parse(file);
//通过XPath表达式快速访问XML文件的节点及其文本值
XPathFactory xpathFactory=XPathFactory.newInstance();
XPath xpath=xpathFactory.newXPath();
System.out.println("==============使用XPath快速访问XML节点值：");
String query="/persons/person/name";
System.out.println(xpath.evaluate(query, doc));
} catch (ParserConfigurationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SAXException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (XPathExpressionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
2.SAXParser使用事件流驱动的方式进行XML文本的解析。
package xmlHandler;
import java.io.File;
import java.io.IOException;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class SAXParserXML {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
SAXParserFactory factory = SAXParserFactory.newInstance();
try {
SAXParser parser = factory.newSAXParser();
File file = new File(System.getProperty("user.dir") + "/person.xml");
parser.parse(file, new PersonXMLHandler());// 此处的file可以使文件、输入流、或URL字符串
} catch (ParserConfigurationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SAXException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
class PersonXMLHandler extends DefaultHandler {
Person person;
String temp = "";
String currenttag = null;
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
// TODO Auto-generated method stub
if (currenttag != null) {
String value = new String(ch, start, length);
if (currenttag.equals("name")) {
person.setName(value);
}
if (currenttag.equals("description")) {
temp += value;// 处理长文本
}
}
}
@Override
public void endDocument() throws SAXException {
// TODO Auto-generated method stub
super.endDocument();
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
// TODO Auto-generated method stub
currenttag=null;
if (qName.endsWith("description")) {
person.setDescription(temp);
temp = "";
}
if (qName.endsWith("person"))
System.out.println("当前解析出的结果：" + person.toString());
}
@Override
public void startDocument() throws SAXException {
// TODO Auto-generated method stub
super.startDocument();
}
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
// TODO Auto-generated method stub
if (qName.equals("person")) {
person = new Person();
person.setSex(attributes.getValue("sex"));
}
currenttag = qName;
}
}
3，StAX同样也是事件流驱动的解析器，只是不再进行startElement、characters的区分。
package xmlHandler;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
public class StAXParserXML {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
StAXParserXML parser=new StAXParserXML();
parser.StAXParser(System.getProperty("user.dir") + "/person.xml");
}
// StAXParser 是一种“pull parser”，允许通过循环来迭代访问所有事件
public void StAXParser(String xmlPath) {
XMLInputFactory factory = XMLInputFactory.newInstance();
Person person=new Person();
File file = new File(xmlPath);
try {
//参数必须是InputStream类型，可以是File的包装器、URL打开的InputStream
XMLStreamReader parser = factory
.createXMLStreamReader(new FileInputStream(file));
// parser遍历xml文档时产生一系列事件
while (parser.hasNext()) {
int event = parser.next();// 获取当前event
if (event == XMLStreamConstants.START_ELEMENT) {//如果是element
if (parser.getLocalName().equals("person")) {//判断标签值
person.setSex(parser.getAttributeValue(0));//获取属性值
}
if(parser.getLocalName().equals("name")){
person.setName(parser.getElementText());//获取元素文本
}
if(parser.getLocalName().equals("description")){
person.setDescription(parser.getElementText());
}
}
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (XMLStreamException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}// 这里的参数只能是InputStream
System.out.println(person.toString());
}
}
具体的参见源代码就行了