使用Stax解析XML
首先是我们用到的位于src下面的books.xml
<?xml version="1.0" encoding="UTF-8"?> <bookstore> <book category="COOKING" aaaaaa="111111"> <title lang="en">Everyday Italian</title> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price> </book> <book category="CHILDREN"> <title lang="en">Harry Potter</title> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="WEB"> <title lang="en">XQuery Kick Start</title> <author>James McGovern</author> <author>Per Bothner</author> <author>Kurt Cagle</author> <author>James Linn</author> <author>Vaidyanathan Nagarajan</author> <year>2003</year> <price>49.99</price> </book> <book category="WEB"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book> </bookstore>
下面是Stax用法
package com.jadyer.stax;
import java.io.InputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.stream.EventFilter;
import javax.xml.stream.FactoryConfigurationError;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.events.XMLEvent;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
/**
* 使用Stax解析XML
* @see Stax(Streaming API for XML)
* @create Mar 17, 2013 5:30:31 PM
* @author 玄玉<http://blog.csdn/net/jadyer>
*/
public class TestStax {
public static void main(String[] args) throws Exception {
cursorParseXML();
iteratorParseXML();
filterParseXML();
xpathParseXML();
xmlStreamWriterXML();
transformerModifyXML();
}
/**
* 基于光标的方式解析XML
*/
private static void cursorParseXML() throws Exception {
XMLInputFactory factory = XMLInputFactory.newInstance();
InputStream is = TestStax.class.getClassLoader().getResourceAsStream("books.xml");
XMLStreamReader reader = factory.createXMLStreamReader(is);
while(reader.hasNext()) {
int type = reader.next();
//处理不同的节点类型
//处理开始节点,如<bookstore>,<book>
if(type == XMLStreamConstants.START_ELEMENT) {
String name = reader.getName().toString();
System.out.println("<" + name + ">");
//打印<book category="COOKING" aaaaaa="111111">节点中的第二个属性值aaaaaa
if(name.equals("book")){
System.out.println("节点属性值为" + reader.getAttributeName(1) + "=" + reader.getAttributeValue(1));
}
if(name.equals("title")) {
System.out.println("书籍[" + reader.getElementText() + "]");
}
if(name.equals("price")) {
System.out.println("的价格为[" + reader.getElementText() + "]");
}
//打印文本节点的内容,注意各xml标签中的空白部分也属于文本节点..并且文本节点是没有name的,所以不能getName
} else if(type == XMLStreamConstants.CHARACTERS) {
System.out.println("文本节点值=[" + reader.getText().trim() + "]");
//处理结束节点,如</book>,</title>
} else if(type == XMLStreamConstants.END_ELEMENT) {
System.out.println("</" + reader.getName() + ">");
}
}
//最后处理完了xml,记得关闭..但不能提前关闭,因为Stax是读一点流就解析一点的
is.close();
}
/**
* 基于迭代模型的方式解析XML
*/
private static void iteratorParseXML() throws Exception {
XMLInputFactory factory = XMLInputFactory.newInstance();
InputStream is = TestStax.class.getClassLoader().getResourceAsStream("books.xml");
XMLEventReader reader = factory.createXMLEventReader(is);
int iteratorNum = 0; //统计遍历的次数
while(reader.hasNext()) {
XMLEvent event = reader.nextEvent();
if(event.isStartElement()) { //通过XMLEvent判断节点类型
String name = event.asStartElement().getName().toString(); //通过event.asxxx转换节点
if(name.equals("title")) {
System.out.print("书籍[" + reader.getElementText() + "]");
}
if(name.equals("price")) {
System.out.println("的价格为[" + reader.getElementText() + "]");
}
}
iteratorNum++;
}
is.close();
System.out.println("本次操作遍历XML的次数合计为[" + iteratorNum + "]次");
}
/**
* 基于Filter的方式解析XML
* @see 可以有效的过滤掉不用进行操作的节点,效率会高一些
*/
private static void filterParseXML() throws Exception {
XMLInputFactory factory = XMLInputFactory.newInstance();
InputStream is = TestStax.class.getClassLoader().getResourceAsStream("books.xml");
XMLEventReader reader = factory.createFilteredReader(factory.createXMLEventReader(is),
new EventFilter() {
@Override
public boolean accept(XMLEvent event) {
if(event.isStartElement()) {
String name = event.asStartElement().getName().toString();
if(name.equals("title") || name.equals("price")){
return true; //返回true表示会显示,false表示不显示
}
}
return false;
}
});
int iteratorNum = 0; //统计遍历的次数
while(reader.hasNext()) {
XMLEvent event = reader.nextEvent();
if(event.isStartElement()) {
String name = event.asStartElement().getName().toString();
if(name.equals("title")) {
System.out.print("书籍[" + reader.getElementText() + "]");
}
if(name.equals("price")) {
System.out.println("的价格为[" + reader.getElementText() + "]");
}
}
iteratorNum++;
}
is.close();
System.out.println("本次操作遍历XML的次数合计为[" + iteratorNum + "]次");
}
/**
* 基于XPath的方式解析XML
*/
private static void xpathParseXML() throws Exception {
InputStream is = TestStax.class.getClassLoader().getResourceAsStream("books.xml");
//创建文档处理对象
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
//通过DocumentBuilder创建doc的文档对象
Document doc = db.parse(is);
//创建XPath
XPath xpath = XPathFactory.newInstance().newXPath();
//第一个参数就是XPath表达式,第二参数就是文档..这里是查找所有属性为category="WEB"的<book>节点
NodeList list = (NodeList)xpath.evaluate("//book[@category='WEB']", doc, XPathConstants.NODESET);
for(int i=0; i<list.getLength(); i++) {
Element e = (Element)list.item(i);
//由于<book>节点下只会有一个<title>节点,所有这里是item(0)
System.out.println(e.getElementsByTagName("title").item(0).getTextContent());
System.out.println(e.getElementsByTagName("price").item(0).getTextContent());
}
is.close();
}
/**
* 使用XMLStreamWriter创建XML
*/
private static void xmlStreamWriterXML() throws XMLStreamException, FactoryConfigurationError {
XMLStreamWriter xsw = XMLOutputFactory.newInstance().createXMLStreamWriter(System.out);
xsw.writeStartDocument("GBK","1.0");
xsw.writeEndDocument(); //先写<?xml version="1.0" encoding="GBK"?>
String namespaceURI = "http://blog.csdn.net/jadyer";
xsw.writeStartElement("pre", "uesr", namespaceURI); //再写<pre:uesr>
xsw.writeStartElement(namespaceURI, "id"); //再写<pre:id>
xsw.writeCharacters("1"); //再写1
xsw.writeEndElement(); //再写</pre:id>
xsw.writeEndElement(); //再写</pre:uesr>
xsw.flush();
xsw.close();
}
/**
* 使用Transformer更新XML
*/
private static void transformerModifyXML() throws Exception, TransformerFactoryConfigurationError {
InputStream is = TestStax.class.getClassLoader().getResourceAsStream("books.xml");
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = db.parse(is);
XPath xpath = XPathFactory.newInstance().newXPath();
//查找内容含title="Learning XML"的<book>节点
NodeList list = (NodeList)xpath.evaluate("//book[title='Learning XML']", doc, XPathConstants.NODESET);
//获取<price>节点,这里只有一个符合条件的<book>节点,所以写成了list.item(0)
Element e = (Element)(((Element)list.item(0)).getElementsByTagName("price").item(0));
e.setTextContent("333.9");
Transformer tran = TransformerFactory.newInstance().newTransformer();
tran.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
tran.setOutputProperty(OutputKeys.INDENT, "yes"); //让<?xml version=...?>与<bookestore>节点之间换行,默认不换行
//修改节点
tran.transform(new DOMSource(doc), new StreamResult(System.out));
is.close();
}
}