前30天常用知识点总结.doc

前30天常用知识点总结： XML的几种读取方式： 方式一： //目标： jaxp如何读取xml文件 public class Demo1 { //创建对象，读取xml内容 public static void main(String[] args) throws Exception { // 1)创建DocumentBuilderFactory实例 //ctrl+2 松开 l或者alt+shift+l DocumentBuilderFactory factroy = DocumentBuilderFactory.newInstance(); //2）通过DocumentBuilderFactory实例创建DocumentBuilder DocumentBuilder builder = factroy.newDocumentBuilder(); //3）通过DocumentBuilder的parse方法读取xml文件，返回一个Document对象 Document doc = builder.parse(src/Locale.xml); } //读出到xml中 public static void write2xml(Document doc) throws TransformerException { TransformerFactory factory = TransformerFactory.newInstance(); Transformer ts = factory.newTransformer(); ts.transform(new DOMSource(doc), new StreamResult(src/exam.xml)); } } 读取方式： //1)读取exam.xml文件 Document doc = XMLUtil.getDocument(); //2)创建student元素，添加idcard,examid属性 Element stuElem = doc.createElement(student); stuElem.setAttribute(idcard, student.getIdcard()); stuElem.setAttribute(examid, student.getExamid()); //3)创建namelocationgrade元素 Element nameElem = doc.createElement(name); Element locElem = doc.createElement(location); Element graElem = doc.createElement(grade); nameElem.setTextContent(student.getName()); locElem.setTextContent(student.getLocation()); graElem.setTextContent(student.getGrade()+); //4)建立student与namelocationgrade元素关系 stuElem.appendChild(nameElem); stuElem.appendChild(locElem); stuElem.appendChild(graElem); //5)建立student与exam的关系 Node root = doc.getElementsByTagName(exam).item(0); root.appendChild(stuElem); //6)写出到exam.xml文件 XMLUtil.write2xml(doc); 方式二： //dom4j方式读取 //创建Document对象 public static Document getDocument() throws DocumentException { SAXReader reader = new SAXReader(); //2)读取xml文件 org.dom4j.Document doc = reader.read(F:/chuanzhikaifa/day13demo/src/db.xml); return (Document) doc; } //写出 public static void write2xml(Document doc) throws IOException { XMLWriter writer = new XM