java将xml字符串转为xml并更改节点内容

可以使用Java中的DOM（Document Object Model）库来实现将XML字符串转换为XML文档，并且可以更改节点内容。下面是一个示例代码：

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import java.io.IOException;
import java.io.StringReader;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

public class XMLUtils {

   public static void main(String[] args) {
      String xmlString = "<root><node1>value1</node1><node2>value2</node2></root>";
      String nodeName = "node1";
      String nodeValue = "new value";

      try {
         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = factory.newDocumentBuilder();
         InputSource inputSource = new InputSource(new StringReader(xmlString));
         Document doc = builder.parse(inputSource);

         // Find the node with the given name
         NodeList nodeList = doc.getElementsByTagName(nodeName);
         Node node = nodeList.item(0);

         // Update the node value
         node.setTextContent(nodeValue);

         // Convert the updated document to a string
         TransformerFactory tf = TransformerFactory.newInstance();
         Transformer transformer = tf.newTransformer();
         DOMSource source = new DOMSource(doc);
         StreamResult result = new StreamResult(System.out);
         transformer.transform(source, result);

      } catch (ParserConfigurationException | SAXException | IOException | TransformerException e) {
         e.printStackTrace();
      }
   }
}

在上面的示例中，我们首先定义了一个XML字符串和要更改的节点名称及节点值。然后，我们使用DocumentBuilderFactory和DocumentBuilder对象将XML字符串转换为XML文档。接下来，我们使用getElementsByTagName方法查找要更改的节点，并使用setTextContent方法更改节点的值。最后，我们使用TransformerFactory和Transformer对象将更新后的XML文档转换回字符串，并将其打印到控制台上。