Java对XML文件增删改查操作示例

Z时代
2024-01-10
分类：综合

本文实例讲述了Java对XML文件增删改查操作。分享给大家供大家参考，具体如下：

xml文件：


<?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>

增删改查 Test.java


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();
    }
  }
}