Java对XML文件增删改查操作示例

<?xml version=\"1.0\" encoding=\"UTF-8\"?>
<books>
  <book>
    <name>哈里波特</name>
    <price>10</price>
    <memo>这是一本很好看的书。</memo>
  </book>
  <book id=\"B02\">
    <name>三国演义</name>
    <price>10</price>
    <memo>四大名著之一。</memo>
  </book>
  <book id=\"B03\">
    <name>水浒</name>
    <price>6</price>
    <memo>四大名著之一。</memo>
  </book>
  <book id=\"B04\">
    <name>红楼</name>
    <price>5</price>
    <memo>四大名著之一。</memo>
  </book>
</books>

import java.io.File;
import java.io.FileOutputStream;
import org.w3c.dom.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.*;
import javax.xml.xpath.*;
public class Test {
  public static void main(String[] args) {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    Element theBook = null, theElem = null, root = null;
    try {
      factory.setIgnoringElementContentWhitespace(true);
      DocumentBuilder db = factory.newDocumentBuilder();
      Document xmldoc = (Document) db.parse(new File(\"Test.xml\"));
      root = xmldoc.getDocumentElement();
      // --- 新建一本书开始 ----
      theBook = xmldoc.createElement(\"book\");
      theElem = xmldoc.createElement(\"name\");
      theElem.setTextContent(\"新书\");
      theBook.appendChild(theElem);
      theElem = xmldoc.createElement(\"price\");
      theElem.setTextContent(\"20\");
      theBook.appendChild(theElem);
      theElem = xmldoc.createElement(\"memo\");
      theElem.setTextContent(\"新书的更好看。\");
      theBook.appendChild(theElem);
      root.appendChild(theBook);
      System.out.println(\"--- 新建一本书开始 ----\");
      output(xmldoc);
      // --- 新建一本书完成 ----
      // --- 下面对《哈里波特》做一些修改。 ----
      // --- 查询找《哈里波特》----
      theBook = (Element) selectSingleNode(\"/books/book[name=\'哈里波特\']\",
          root);
      System.out.println(\"--- 查询找《哈里波特》 ----\");
      output(theBook);
      // --- 此时修改这本书的价格 -----
      theBook.getElementsByTagName(\"price\").item(0).setTextContent(\"15\");// getElementsByTagName返回的是NodeList，所以要跟上item(0)。另外，getElementsByTagName(\"price\")相当于xpath的\".//price\"。
      System.out.println(\"--- 此时修改这本书的价格 ----\");
      output(theBook);
      // --- 另外还想加一个属性id，值为B01 ----
      theBook.setAttribute(\"id\", \"B01\");
      System.out.println(\"--- 另外还想加一个属性id，值为B01 ----\");
      output(theBook);
      // --- 对《哈里波特》修改完成。 ----
      // --- 要用id属性删除《三国演义》这本书 ----
      theBook = (Element) selectSingleNode(\"/books/book[@id=\'B02\']\", root);
      System.out.println(\"--- 要用id属性删除《三国演义》这本书 ----\");
      output(theBook);
      theBook.getParentNode().removeChild(theBook);
      System.out.println(\"--- 删除后的ＸＭＬ ----\");
      output(xmldoc);
      // --- 再将所有价格低于10的书删除 ----
      NodeList someBooks = selectNodes(\"/books/book[price<10]\", root);
      System.out.println(\"--- 再将所有价格低于10的书删除 ---\");
      System.out.println(\"--- 符合条件的书有　\" + someBooks.getLength()
          + \"本。 ---\");
      for (int i = 0; i < someBooks.getLength(); i++) {
        someBooks.item(i).getParentNode().removeChild(someBooks.item(i));
      }
      output(xmldoc);
      saveXml(\"Test1_Edited.xml\", xmldoc);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  /**
   * 将node的XML字符串输出到控制台
   *
   * @param node
   */
  public static void output(Node node) {
    TransformerFactory transFactory = TransformerFactory.newInstance();
    try {
      Transformer transformer = transFactory.newTransformer();
      transformer.setOutputProperty(\"encoding\", \"gb2312\");
      transformer.setOutputProperty(\"indent\", \"yes\");
      DOMSource source = new DOMSource();
      source.setNode(node);
      StreamResult result = new StreamResult();
      result.setOutputStream(System.out);
      transformer.transform(source, result);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  /**
   * 查找节点，并返回第一个符合条件节点
   *
   * @param express
   * @param source
   * @return
   */
  public static Node selectSingleNode(String express, Object source) {
    Node result = null;
    XPathFactory xpathFactory = XPathFactory.newInstance();
    XPath xpath = xpathFactory.newXPath();
    try {
      result = (Node) xpath.evaluate(express, source, XPathConstants.NODE);
    } catch (XPathExpressionException e) {
      e.printStackTrace();
    }
    return result;
  }
  /**
   * 查找节点，返回符合条件的节点集。
   * @param express
   * @param source
   * @return
   */
  public static NodeList selectNodes(String express, Object source) {
    NodeList result = null;
    XPathFactory xpathFactory = XPathFactory.newInstance();
    XPath xpath = xpathFactory.newXPath();
    try {
      result = (NodeList) xpath.evaluate(express, source,
          XPathConstants.NODESET);
    } catch (XPathExpressionException e) {
      e.printStackTrace();
    }
    return result;
  }
  /**
   * 将Document输出到文件
   * @param fileName
   * @param doc
   */
  public static void saveXml(String fileName, Document doc) {
    TransformerFactory transFactory = TransformerFactory.newInstance();
    try {
      Transformer transformer = transFactory.newTransformer();
      transformer.setOutputProperty(\"indent\", \"yes\");
      DOMSource source = new DOMSource();
      source.setNode(doc);
      StreamResult result = new StreamResult();
      result.setOutputStream(new FileOutputStream(fileName));
      transformer.transform(source, result);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}