Use the Document + XPath that comes with the JDK to parse XML and record
Ready to work
PCDATA in inventory.dtd and inventory.xml files dtd means parsed character data. Think of character data as the text between the start and end tags of XML elements. PCDATA is the text that will be parsed by the parser.
CDATA means character data. CDATA is text that will not be parsed by the parser.
- inventory.dtd
<?xml version="1.0" encoding="UTF-8"?>
<!ELEMENT inventory (book+)>
<!ELEMENT book (title,author,dynasty,price)>
<!ATTLIST book year CDATA #REQUIRED>
<!ELEMENT title (#PCDATA)>
<!ELEMENT author (#PCDATA)>
<!ELEMENT dynasty (#PCDATA)>
<!ELEMENT price (#PCDATA)>
- inventory.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE inventory SYSTEM "D:\\work-space\\springboot\\src\\main\\resources\\inventory.dtd">
<inventory>
<book year="2012">
<title>菜根谭</title>
<author>洪应明</author>
<dynasty>明朝</dynasty>
<price>38</price>
</book>
<book year="2013">
<title>曾国藩家书</title>
<author>曾国藩</author>
<dynasty>清朝</dynasty>
<price>70</price>
</book>
<book year="2014">
<title>高等代数</title>
<author>丘维声</author>
<dynasty>中华人民共和国</dynasty>
<price>86</price>
</book>
</inventory>
- Tools
Learn from the content of the blog [ Analyze XML with DOM, and quickly query XML nodes with xpath ]
package com.me.util;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import java.io.File;
/**
* @Author yanyg
* @Date 2020/6/10 16:37
* @Descripetion admin
*/
public class ParseXmlUtil {
//查询价格大于80的书的标题的内容
private static final String XPath_EXPRESSION = "//book[price>80]/title/text()";
public static void main(String[] args) {
try {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
//开启验证：
documentBuilderFactory.setValidating(true);
documentBuilderFactory.setNamespaceAware(false);
documentBuilderFactory.setIgnoringComments(true);
documentBuilderFactory.setIgnoringElementContentWhitespace(true);
documentBuilderFactory.setCoalescing(false);
documentBuilderFactory.setExpandEntityReferences(true);
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
//设置异常处理：
documentBuilder.setErrorHandler(new ErrorHandler() {
@Override
public void warning(SAXParseException exception) throws SAXException {
System.out.println("warn:" + exception.getMessage());
}
@Override
public void error(SAXParseException exception) throws SAXException {
System.out.println("error:" + exception.getMessage());
}
@Override
public void fatalError(SAXParseException exception) throws SAXException {
System.out.println("fatalError:" + exception.getMessage());
}
});
//将inventory.xml加载到一个Document的对象中：
String filePath = "D:\\work-space\\springboot\\src\\main\\resources\\inventory.xml";
Document document = documentBuilder.parse(new File(filePath));
//根据表达式查询内容
processParseXmlWithXpath(document, XPath_EXPRESSION);
} catch (Exception e) {
e.printStackTrace();
} finally {
}
}
private static void processParseXmlWithXpath(Document document, String xPathExpression) throws Exception {
// 表达式可以参考：https://blog.csdn.net/zlj_blog/article/details/54092534
xPathExpression = "/inventory/book/title";
//创建XPathFactory:
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xPath = xPathFactory.newXPath();
NodeList nodeList = (NodeList) xPath.evaluate(xPathExpression, document, XPathConstants.NODESET);
for (int i = 0; i < nodeList.getLength(); i++) {
Node item = nodeList.item(i);
System.out.println(item.getNodeName() + "=" + item.getTextContent());
}
}
private static void processParseXmlWithXpathExpress(Document document, String xPathExpression) throws Exception {
//创建XPathFactory:
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xPath = xPathFactory.newXPath();
XPathExpression expression = xPath.compile(xPathExpression);
Object result = expression.evaluate(document, XPathConstants.NODESET);
if (result instanceof NodeList) {
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(String.format("%s=%s", nodes.item(i).getNodeName(), nodes.item(i).getNodeValue()));
}
}
}
}