org.w3c.dom。 XML解析 练习

HTML文档

  1 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.transform.Transformer;
 import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.stream.StreamResult;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;

 public class DomDemolianxi {
     public static void main(String[] args) {

         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = null;
         Document doc = null;
         try {
             builder = factory.newDocumentBuilder();
             doc = builder.parse("src/book.xml");
         //===============================================
 //            test1(doc);
 //            test2(doc);
             test3(doc);
 //            test4(doc);
 //            test5(doc);
 //            test6(doc);
 //            test7(doc);
 //            test8(doc);
         //===============================================
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     // 1.获取第二本书的作者
     public static void test1(Document doc){
         NodeList nl = doc.getElementsByTagName("作者");
         System.out.println(nl.item(1).getTextContent());
     }

     // 2.获取全部元素的名称
     public static void test2(Node d){
         if(d.getNodeType()==Node.ELEMENT_NODE){
             System.out.println(d.getNodeName());
         }
         NodeList nl = d.getChildNodes();
         for(int i=0;i<nl.getLength();i++){
             Node d1 = nl.item(i);
             test2(d1);
         }
     }

     // 3.把zhd的书售价改为10元
     public static void test3(Document doc) throws Exception{
         NodeList nl = doc.getElementsByTagName("售价");
         nl.item(1).setTextContent("10元");
         //把内存中dom树写回xml
         TransformerFactory factory = TransformerFactory.newInstance();
         Transformer    transformer = factory.newTransformer();
         transformer.transform(new DOMSource(doc),new StreamResult("src/book.xml"));
     }

     // 4.加一个子节点 第二本书 内部价 5角
     public static void test4(Document doc) throws Exception{
         NodeList nl = doc.getElementsByTagName("书");
         Node secondBook = nl.item(1);
         Element e = doc.createElement("内部价");
         e.setTextContent("7元");
         secondBook.appendChild(e);
         //把内存中dom树写回xml
         TransformerFactory factory = TransformerFactory.newInstance();
         Transformer    transformer = factory.newTransformer();
         transformer.transform(new DOMSource(doc),new StreamResult("src/book.xml"));
     }

     // 5.在第二本书 售价的前面增加批发价 5元
     public static void test5(Document doc) throws Exception{
         Node son = doc.getElementsByTagName("售价").item(1);
         Node dad = son.getParentNode();
         Element e = doc.createElement("批发价");
         e.setTextContent("5元");
         dad.insertBefore(e, son);
         //把内存中dom树写回xml
         TransformerFactory factory = TransformerFactory.newInstance();
         Transformer    transformer = factory.newTransformer();
         transformer.transform(new DOMSource(doc),new StreamResult("src/book.xml"));
     }

     // 6.删除第二本书的内部价
     public static void test6(Document doc) throws Exception{
         Node son = doc.getElementsByTagName("内部价").item(0);
         Node dad = son.getParentNode();
         dad.removeChild(son);
         //把内存中dom树写回xml
         TransformerFactory factory = TransformerFactory.newInstance();
         Transformer    transformer = factory.newTransformer();
         transformer.transform(new DOMSource(doc),new StreamResult("src/book.xml"));
     }

     // 7.获取第一本书的出版社
     public static void test7(Document doc) throws Exception{
         Element nl =(Element) doc.getElementsByTagName("书").item(0);
         String n =nl.getAttribute("出版社");
         System.out.println(n);
     }

     // 8.给第二本书加上出版社（属性）
     public static void test8(Document doc) throws Exception{
         Element nl = (Element)doc.getElementsByTagName("书").item(1);
         nl.setAttribute("出版社", "人民出版社");
         //把内存中dom树写回xml
         TransformerFactory factory = TransformerFactory.newInstance();
         Transformer    transformer = factory.newTransformer();
         transformer.transform(new DOMSource(doc),new StreamResult("src/book.xml"));
     }

 }

XML文档：

 <?xml version="1.0" encoding="UTF-8" standalone="no"?><书架>
     <书 id="1" 出版社="wwg日报">
         <书名>传奇人生</书名>
         <作者>wwg</作者>
         <售价>999.0元</售价>
     </书>
     <书 id="2" 出版社="人民出版社">
         <书名>论吃</书名>
         <作者>zhd</作者>
         <批发价>5元</批发价>
         <售价>10元</售价>

     </书>
 </书架>