java 遍历xml文件

在 Java 中，可以使用 DOM（文档对象模型）或 SAX（简单 API for XML）来遍历 XML 文件。DOM 是一种将整个 XML 文档加载到内存中的方法，而 SAX 是一种基于事件驱动的方法，它会在遍历 XML 文件时触发不同的事件。

以下是使用 DOM 和 SAX 遍历 XML 文件的示例代码：

使用 DOM：

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class XMLReader {
  public static void main(String[] args) {
    try {
      File inputFile = new File("input.xml");
      DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
      Document doc = dBuilder.parse(inputFile);
      doc.getDocumentElement().normalize();
      System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
      NodeList nList = doc.getElementsByTagName("student");
      System.out.println("----------------------------");
      for (int temp = 0; temp < nList.getLength(); temp++) {
        Node nNode = nList.item(temp);
        System.out.println("\nCurrent Element :" + nNode.getNodeName());
        if (nNode.getNodeType() == Node.ELEMENT_NODE) {
          Element eElement = (Element) nNode;
          System.out.println("Student id : " + eElement.getAttribute("id"));
          System.out.println("First Name : " + eElement.getElementsByTagName("firstname").item(0).getTextContent());
          System.out.println("Last Name : " + eElement.getElementsByTagName("lastname").item(0).getTextContent());
          System.out.println("Age : " + eElement.getElementsByTagName("age").item(0).getTextContent());
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

使用 SAX：

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.helpers.DefaultHandler;

public class XMLReader {
  public static void main(String[] args) {
    try {
      File inputFile = new File("input.xml");
      SAXParserFactory factory = SAXParserFactory.newInstance();
      SAXParser saxParser = factory.newSAXParser();
      DefaultHandler handler = new DefaultHandler() {
        boolean bfname = false;
        boolean blname = false;
        boolean bage = false;
        boolean bid = false;
        public void startElement(String uri, String localName, String qName, Attributes attributes) {
          if (qName.equalsIgnoreCase("STUDENT")) {
            String id = attributes.getValue("id");
            System.out.println("Student id : " + id);
            bid = true;
          } else if (qName.equalsIgnoreCase("FIRSTNAME")) {
            bfname = true;
          } else if (qName.equalsIgnoreCase("LASTNAME")) {
            blname = true;
          } else if (qName.equalsIgnoreCase("AGE")) {
            bage = true;
          }
        }
        public void endElement(String uri, String localName, String qName) {
        }
        public void characters(char ch[], int start, int length) {
          if (bfname) {
            System.out.println("First Name : " + new String(ch, start, length));
            bfname = false;
          } else if (blname) {
            System.out.println("Last Name : " + new String(ch, start, length));
            blname = false;
          } else if (bage) {
            System.out.println("Age : " + new String(ch, start, length));
            bage = false;
          }
        }
      };
      saxParser.parse(inputFile, handler);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

以上代码可以读取以下格式的 XML 文件：

<?xml version="1.0" encoding="UTF-8"?>
<CLASS>
  <STUDENT id="1">
    <FIRSTNAME>John</FIRSTNAME>
    <LASTNAME>Doe</LASTNAME>
    <AGE>23</AGE>
  </STUDENT>
  <STUDENT id="2">
    <FIRSTNAME>Jane</FIRSTNAME>
    <LASTNAME>Smith</LASTNAME>
    <AGE>25</AGE>
  </STUDENT>
</CLASS>

希望能对你有所帮助！