java操作xml的方法汇总及解析

/** * 和cn.hutool.core.util.XmlUtil许多功能重合, 本类可以当做学习的例子 * 可以直接使用cn.hutool.core.util.XmlUtil * * @author TimFruit * @date 19-11-2 下午5:22 */public class XmlUtils {  // --------------------------------------  public static Document createXml(){    return XmlUtil.createXml();  }  // --------------------------------------  /**   * 读取xml文档   * @param xmlInputStream   * @return   */  public static Document readXml(InputStream xmlInputStream){    return readXml(xmlInputStream, false);  }  public static Document readXml(InputStream xmlInputStream, boolean validate){ // 参考mybatis parsing模块    try {      DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();      factory.setValidating(validate);      factory.setNamespaceAware(false);      factory.setIgnoringComments(true);      factory.setIgnoringElementContentWhitespace(false);      factory.setCoalescing(false);      factory.setExpandEntityReferences(true);      DocumentBuilder builder=factory.newDocumentBuilder();      return builder.parse(xmlInputStream);    } catch (ParserConfigurationException e) {      throw new RuntimeException(e);    } catch (SAXException e) {      throw new RuntimeException(e);    } catch (IOException e) {      throw new RuntimeException(e);    }  }  public static Document readXml(String xmlStr){    return XmlUtil.parseXml(xmlStr); //使用hutool  }  // --------------------------------------  // 根据路径获取某一节点  public static XPath newXpath(){    return XPathFactory.newInstance().newXPath();  }  /**   * 根据路径获取某一节点, 语法看 https://www.w3school.com.cn/xpath/xpath_syntax.asp   * @param expression   * @param root 可以是document, 可以是Node等其他节点   * @param xpath   * @return 返回的节点可以修改   */  public static Node evalNode(String expression, Object root, XPath xpath){    return (Node)evaluate(expression, root, XPathConstants.NODE, xpath);  }  public static NodeList evalNodeList(String expression, Object root, XPath xpath){    return (NodeList)evaluate(expression, root, XPathConstants.NODESET, xpath);  }  public static Double evalDouble(String expression, Object root, XPath xpath) {    return (Double) evaluate(expression, root, XPathConstants.NUMBER, xpath);  }  public static Boolean evalBoolean(String expression, Object root, XPath xpath) {    return (Boolean) evaluate(expression, root, XPathConstants.BOOLEAN, xpath);  }  public static String evalString(String expression, Object root, XPath xpath) {    return (String) evaluate(expression, root, XPathConstants.STRING, xpath);  }  public static Long evalLong(String expression, Object root, XPath xpath){    return Long.valueOf(evalString(expression, root, xpath));  }  public static Integer evalInteger(String expression, Object root, XPath xpath){    return Integer.valueOf(evalString(expression, root, xpath));  }  public static Float evalFloat(String expression, Object root, XPath xpath){    return Float.valueOf(evalString(expression, root, xpath));  }  public static Short evalShort(String expression, Object root, XPath xpath){    return Short.valueOf(evalString(expression, root, xpath));  }  private static Object evaluate(String expression, Object root, QName returnType, XPath xpath) {    try {      return xpath.evaluate(expression, root, returnType);    } catch (Exception e) {      throw new RuntimeException("Error evaluating XPath. Cause: " + e, e);    }  }  // --------------------------------------  // 转成string  public static String toStr(Node node){    return toStr(node, false);  }  public static String toStr(Node node, boolean isPretty){    return toStr(node, "utf-8", isPretty);  }  /**   *   * @param node   * @param charset 编码   * @param isPretty 是否格式化输出   * @return   */  public static String toStr(Node node, String charset, boolean isPretty){    final StringWriter writer = StrUtil.getWriter();    final int INDENT_DEFAULT=2;    try {      XmlUtil.transform(new DOMSource(node), new StreamResult(writer), charset, isPretty ? INDENT_DEFAULT : 0);    } catch (Exception e) {      throw new UtilException(e, "Trans xml document to string error!");    }    return writer.toString();  }  //----------------------------------------  // 和java bean转换  public static JSONObject toJSONObject(String xmlStr){    return XML.toJSONObject(xmlStr);  }  public static JSONObject toJSONObject(Node node){    String xmlStr=toStr(node);    return toJSONObject(xmlStr);  }  public static <T> T toBean(Node node, Class<T> clazz){    return toJSONObject(node).toBean(clazz);  }  public static Node toNode(Object obj){    String xml=toXml(obj);    Node rootNode=readXml(xml).getFirstChild();    return rootNode;  }  public static String toXml(Object obj){    return XML.toXml(obj);  }}

@Test  public void readXmlFromInputStreamTest(){    BufferedInputStream bis=FileUtil.getInputStream("xml/bookstore.xml");    Document document=XmlUtils.readXml(bis);    String nodeName=document.getFirstChild().getNodeName();    System.out.println(nodeName);    Assert.assertTrue(nodeName.equals("bookstore"));  }  @Test  public void readXmlStringTest() throws IOException {    BufferedInputStream bis=FileUtil.getInputStream("xml/bookstore.xml");    String xmlStr=StreamUtils.copyToString(bis, Charset.defaultCharset());    Document document=XmlUtils.readXml(xmlStr);    String nodeName=document.getFirstChild().getNodeName();    System.out.println(nodeName);    Assert.assertTrue(nodeName.equals("bookstore"));  }  // -------------------------------------------- xpath  /*  https://www.w3school.com.cn/xpath/xpath_syntax.asp  nodename   选取此节点的所有子节点。  /   从根节点选取。  //   从匹配选择的当前节点选择文档中的节点，而不考虑它们的位置。  .   选取当前节点。  ..   选取当前节点的父节点。  @   选取属性。   */  @Test  public void evalNodeTest(){    BufferedInputStream bis=FileUtil.getInputStream("xml/bookstore.xml");    Document document=XmlUtils.readXml(bis);    XPath xpath=XmlUtils.newXpath();    // 1. 使用xpath表达式读取根节点    Node rootNode=XmlUtils.evalNode("/bookstore", document, xpath);    Assert.assertEquals("bookstore", rootNode.getNodeName());    // 2. 使用xpath表达式读取nodeList    NodeList bookNodeList =XmlUtils.evalNodeList("/bookstore/book", document, xpath);    Node bookNode=null;    for(int i=0; i<bookNodeList.getLength(); i++){      bookNode=bookNodeList.item(i);      Assert.assertEquals("book", bookNode.getNodeName());    }    // 3. 使用xpath表达式从节点读取nodeList    bookNodeList=XmlUtils.evalNodeList("/book", rootNode, xpath);    for(int i=0; i<bookNodeList.getLength(); i++){      bookNode=bookNodeList.item(i);      Assert.assertEquals("book", bookNode.getNodeName());    }    // 4. 使用xpath表达式读取属性 数组表达式从1开始, /@ 修饰获取属性    String lang=XmlUtils.evalString("/bookstore/book[1]/title/@lang", document, xpath);    Assert.assertEquals("en", lang);    lang=XmlUtils.evalString("/bookstore/book[2]/title/@lang", document, xpath);    Assert.assertEquals("cn", lang);  }  // --------------------------------- 转换  @Test  public void xmlToJSONObjectTest() throws IOException {    BufferedInputStream bis=FileUtil.getInputStream("xml/bookstore.xml");    String xmlStr=StreamUtils.copyToString(bis, Charset.forName("utf-8"));    JSONObject jso=XmlUtils.toJSONObject(xmlStr);    Assert.assertTrue(jso.getJSONObject("bookstore")!=null);    Assert.assertTrue(jso.getJSONObject("bookstore").getJSONArray("book")!=null);  }  @Test  public void nodeToJSONObjectTest(){    BufferedInputStream bis=FileUtil.getInputStream("xml/bookstore.xml");    Document document=XmlUtils.readXml(bis);    JSONObject jso=XmlUtils.toJSONObject(document);    Assert.assertTrue(jso.getJSONObject("bookstore")!=null);    Assert.assertTrue(jso.getJSONObject("bookstore").getJSONArray("book")!=null);  }  @Test  public void toBeanTest(){    BufferedInputStream bis=FileUtil.getInputStream("xml/bookstore.xml");    Document document=XmlUtils.readXml(bis);    XmlBookstoreDto dto=XmlUtils.toBean(document, XmlBookstoreDto.class);    Bookstore bookstore=dto.getBookstore();    Assert.assertNotNull(bookstore);    List<Book> bookList=bookstore.getBook();    Book book1=bookList.get(0);    Assert.assertTrue(book1.getTitle().getLang().equals("en"));    Assert.assertTrue(book1.getTitle().getContent().equals("Harry Potter"));    Assert.assertTrue(book1.getAuthor().equals("J K. Rowling"));    Book book2=bookList.get(1);    Assert.assertTrue(book2.getTitle().getLang().equals("cn"));    Assert.assertTrue(book2.getTitle().getContent().equals("where I am from"));    Assert.assertTrue(book2.getAuthor().equals("timfruit"));  }