这是最终生效的代码！有关不同部分的说明，请参阅问题更新。
import java.io.*;import java.nio.channels.*;import javax.xml.parsers.*;import javax.xml.transform.*;import javax.xml.transform.dom.DOMSource;import javax.xml.transform.stream.StreamResult;import javax.xml.xpath.*;import org.w3c.dom.*;import org.xml.sax.SAXException;public class Test2{ String path = "...Test 2.xml"; public Test2(){ document doc = null; documentBuilderFactory dbFactory; documentBuilder dBuilder; NodeList itemList; Transformer transformer; FileChannel channel; Element newElement; int prevNumber; TransformerFactory transformerFactory ; DOMSource source; StreamResult result; NonClosingInputStream ncis = null; try { channel = new RandomAccessFile(new File(path), "rw").getChannel(); FileLock lock = channel.lock(0L, Long.MAX_VALUE, false); try { dbFactory = documentBuilderFactory.newInstance(); dBuilder = dbFactory.newdocumentBuilder(); ncis = new NonClosingInputStream(Channels.newInputStream(channel)); doc = dBuilder.parse(ncis); } catch (SAXException | IOException | ParserConfigurationException e) { e.printStackTrace(); } doc.getdocumentElement().normalize(); itemList = doc.getElementsByTagName("Item"); newElement = doc.createElement("Item"); prevNumber = Integer.parseInt(((Element) itemList.item(itemList.getLength() - 1)).getAttribute("Number")); newElement.setAttribute("Number", (prevNumber + 1) + ""); doc.getdocumentElement().appendChild(newElement); transformerFactory = TransformerFactory.newInstance(); transformer = transformerFactory.newTransformer(); source = new DOMSource(doc); channel.truncate(0); result = new StreamResult(Channels.newOutputStream(channel)); transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4"); transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no"); transformer.setOutputProperty(OutputKeys.METHOD, "xml"); transformer.setOutputProperty(OutputKeys.INDENT, "yes"); transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8"); transformer.transform(source, result); channel.close(); } catch (IOException | TransformerException e) { e.printStackTrace(); } finally { try { ncis.reallyClose(); } catch (IOException e) { e.printStackTrace(); } } } class NonClosingInputStream extends FilterInputStream { public NonClosingInputStream(InputStream it) { super(it); } @Override public void close() throws IOException { // Do nothing. } public void reallyClose() throws IOException { // Actually close. in.close(); } } public static void main(String[] args){ new Test2(); }}
