xml学习笔记

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将要读取的xml文档：

<?xml version="1.0" encoding="UTF-8"?><书架><书><书名>java开发</书名><作者>andrew</作者><售价>29.00元</售价></书><书><书名>JAva就业培训</书名><作者>andrew</作者><售价>29.00元</售价></书></书架>

1.读取xml中节点的值；

public  void readXML() throws Exception{//1.创建工厂DocumentBuilderFactory factory =  DocumentBuilderFactory.newInstance();//2.得到dom解析器DocumentBuilder  builder =  factory.newDocumentBuilder();//3.解析xml文档，得到代表文档的documentDocument document =  builder.parse("src/book.xml");//读文档NodeList list = document.getElementsByTagName("书名");Node nameNode = list.item(1);String bookName = nameNode.getTextContent();System.out.println(bookName);}

2.读取xml中所有节点

@Testpublic void readAllNodeName() throws Exception{DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();DocumentBuilder builder = factory.newDocumentBuilder();Document document = builder.parse("src/book.xml");//得到根节点Node rootNode = document.getElementsByTagName("书架").item(0);listAllNode(rootNode);}private void listAllNode(Node rootNode) {if(rootNode instanceof Element){System.out.println(rootNode.getNodeName());}NodeList  childNodes = rootNode.getChildNodes();for(int i=0; i<childNodes.getLength(); i++){Node childNode = childNodes.item(i);listAllNode(childNode);}

3.向xml中添加节点

//向xml文档中添加节点，《售价》44.00元《/售价》@Testpublic void add() throws Exception{DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();DocumentBuilder builder = factory.newDocumentBuilder();Document document = builder.parse("src/book.xml");//创建节点Element price = document.createElement("售价");price.setTextContent("44.00元");//把节点挂 到第一本书的节点下 Element book = (Element) document.getElementsByTagName("书").item(0); book.appendChild(price);  //把更新后的内存的数据写回xml中 TransformerFactory tfFactory = TransformerFactory.newInstance(); Transformer tf = tfFactory.newTransformer(); tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/book.xml")));}

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