读取XML文档:
读写XML文档主要依赖于org.dom4j.io包,有DOMReader和SAXReader两种方式。因为利用了相同的接口,它们的调用方式是一样的。
public static Document load(String filename) { Document document = null; try { SAXReader saxReader = new SAXReader(); document = saxReader.read(new File(filename)); // 读取XML文件,获得document对象 } catch (Exception ex) { ex.printStackTrace(); } return document;
} public static Document load(URL url) { Document document = null; try { SAXReader saxReader = new SAXReader(); document = saxReader.read(url); // 读取XML文件,获得document对象 } catch (Exception ex) { ex.printStackTrace(); } return document;
}
//读取指定的xml文件之后返回一个Document对象,这个对象代表了整个XML文档,用于各种Dom运算。执照XML文件头所定义的编码来转换。
获取根节点
根节点是xml分析的开始,任何xml分析工作都需要从根开始
Xml xml = new Xml(); Document dom = xml.load(path + "/" + file); Element root = dom.getRootElement();
新增一个节点以及其下的子节点与数据
Element menuElement = root.addElement("menu"); Element engNameElement = menuElement.addElement("engName"); engNameElement.setText(catNameEn); Element chiNameElement = menuElement.addElement("chiName"); chiNameElement.setText(catName);
写入XML文件
注意文件操作的包装类是乱码的根源
public static boolean doc2XmlFile(Document document, String filename) { boolean flag = true; try { XMLWriter writer = new XMLWriter(new OutputStreamWriter( new FileOutputStream(filename), "UTF-8")); writer.write(document); writer.close(); } catch (Exception ex) { flag = false; ex.printStackTrace(); } System.out.println(flag); return flag;
}
Dom4j通过XMLWriter将Document对象表示的XML树写入指定的文件,并使用OutputFormat格式对象指定写入的风格和编码方法。调用OutputFormat.createPrettyPrint()方法可以获得一个默认的pretty print风格的格式对象。对OutputFormat对象调用setEncoding()方法可以指定XML文件的编码方法。
public void writeTo(OutputStream out, String encoding) throws UnsupportedEncodingException, IOException { OutputFormat format = OutputFormat.createPrettyPrint(); format.setEncoding("gb2312"); XMLWriter writer = new XMLWriter(System.out, format); writer.write(doc); writer.flush(); return; }
遍历xml节点
对Document对象调用getRootElement()方法可以返回代表根节点的Element对象。拥有了一个Element对象后,可以对该对象调用elementIterator()方法获得它的子节点的Element对象们的一个迭代器。使用(Element)iterator.next()方法遍历一个iterator并把每个取出的元素转化为Element类型。
public boolean isOnly(String catNameEn, HttpServletRequest request, String xml) { boolean flag = true; String path = request.getRealPath(""); Document doc = load(path + "/" + xml); Element root = doc.getRootElement(); for (Iterator i = root.elementIterator(); i.hasNext();) { Element el = (Element) i.next(); if (catNameEn.equals(el.elementTextTrim("engName"))) { flag = false; break; } } return flag;
}
创建xml文件
public static void main(String args[]) { String fileName = "c:/text.xml"; Document document = DocumentHelper.createDocument();// 建立document对象,用来操作xml文件 Element booksElement = document.addElement("books");// 建立根节点 booksElement.addComment("This is a test for dom4j ");// 加入一行注释 Element bookElement = booksElement.addElement("book");// 添加一个book节点 bookElement.addAttribute("show", "yes");// 添加属性内容 Element titleElement = bookElement.addElement("title");// 添加文本节点 titleElement.setText("ajax in action");// 添加文本内容 try { XMLWriter writer = new XMLWriter(new FileWriter(new File(fileName))); writer.write(document) //写入writer.close(); } catch (Exception e) { e.printStackTrace(); } }
修改节点属性
public static void modifyXMLFile() { String oldStr = "c:/text.xml"; String newStr = "c:/text1.xml"; Document document = null; //修改节点的属性 try { SAXReader saxReader = new SAXReader(); // 用来读取xml文档 document = saxReader.read(new File(oldStr)); // 读取xml文档 List list = document.selectNodes("/books/book/@show");// 用xpath查找节点book的属性 Iterator iter = list.iterator(); while (iter.hasNext()) { Attribute attribute = (Attribute) iter.next(); if (attribute.getValue().equals("yes")) attribute.setValue("no"); } } catch (Exception e) { e.printStackTrace(); } //修改节点的内容 try { SAXReader saxReader = new SAXReader(); // 用来读取xml文档 document = saxReader.read(new File(oldStr)); // 读取xml文档 List list = document.selectNodes("/books/book/title");// 用xpath查找节点book的内容 Iterator iter = list.iterator(); while (iter.hasNext()) { Element element = (Element) iter.next(); element.setText("xxx");// 设置相应的内容 } } catch (Exception e) { e.printStackTrace(); } try { XMLWriter writer = new XMLWriter(new FileWriter(new File(newStr))); writer.write(document); writer.close(); } catch (Exception ex) { ex.printStackTrace(); } }
删除节点
public static void removeNode() { String oldStr = "c:/text.xml"; String newStr = "c:/text1.xml"; Document document = null; try { SAXReader saxReader = new SAXReader();// 用来读取xml文档 document = saxReader.read(new File(oldStr));// 读取xml文档 List list = document.selectNodes("/books/book");// 用xpath查找对象 Iterator iter = list.iterator(); while (iter.hasNext()) { Element bookElement = (Element) iter.next(); // 创建迭代器,用来查找要删除的节点,迭代器相当于指针,指向book下所有的title节点 Iterator iterator = bookElement.elementIterator("title"); while (iterator.hasNext()) { Element titleElement = (Element) iterator.next(); if (titleElement.getText().equals("ajax in action")) { bookElement.remove(titleElement); } } } } catch (Exception e) { e.printStackTrace(); } try { XMLWriter writer = new XMLWriter(new FileWriter(new File(newStr))); writer.write(document); writer.close(); } catch (Exception ex) { ex.printStackTrace(); } }