java解析返回xml数据

在Java中解析XML数据通常使用Java API for XML Processing（JAXP），它是Java语言中用于XML处理的标准API之一。JAXP提供了DOM解析器和SAX解析器。

DOM解析器会将整个XML文档加载到内存中作为一个树形结构，可以通过遍历树来访问XML文档中的各个元素和属性。以下是使用DOM解析器解析XML数据的示例代码：

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import org.w3c.dom.Element;
import java.io.File;

public class XMLParser {

   public static void main(String argv[]) {

      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("employee");

         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("Employee 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("Email : " + eElement.getElementsByTagName("email").item(0).getTextContent());
               System.out.println("Salary : " + eElement.getElementsByTagName("salary").item(0).getTextContent());

            }
         }
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

另外，SAX解析器是一种基于事件驱动的解析器，它逐行解析XML文档，可以在解析过程中处理文档中的各个元素和属性。使用SAX解析器需要实现org.xml.sax.ContentHandler接口的方法，以下是使用SAX解析器解析XML数据的示例代码：

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;
import java.io.File;

public class XMLParser extends DefaultHandler {

   boolean bFirstName = false;
   boolean bLastName = false;
   boolean bEmail = false;
   boolean bSalary = false;

   public void startElement(String uri, String localName,String qName, 
                Attributes attributes) throws SAXException {

      if (qName.equalsIgnoreCase("employee")) {
         String id = attributes.getValue("id");
         System.out.println("Employee id : " + id);
      } else if (qName.equalsIgnoreCase("firstName")) {
         bFirstName = true;
      } else if (qName.equalsIgnoreCase("lastName")) {
         bLastName = true;
      } else if (qName.equalsIgnoreCase("email")) {
         bEmail = true;
      } else if (qName.equalsIgnoreCase("salary")) {
         bSalary = true;
      }
   }

   public void characters(char ch[], int start, int length) throws SAXException {

      if (bFirstName) {
         System.out.println("First Name: " + new String(ch, start, length));
         bFirstName = false;
      } else if (bLastName) {
         System.out.println("Last Name: " + new String(ch, start, length));
         bLastName = false;
      } else if (bEmail) {
         System.out.println("Email: " + new String(ch, start, length));
         bEmail = false;
      } else if (bSalary) {
         System.out.println("Salary: " + new String(ch, start, length));
         bSalary = false;
      }
   }

   public static void main(String argv[]) {

      try {
         File inputFile = new File("input.xml");
         SAXParserFactory factory = SAXParserFactory.newInstance();
         SAXParser saxParser = factory.newSAXParser();
         XMLParser userhandler = new XMLParser();
         saxParser.parse(inputFile, userhandler);
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

以上是两种常见的解析XML数据的方法，具体使用哪种方法取决于项目需求和个人喜好。