DOM的概念和简单应用：使用DOM解析XML数据
概念：DOM是Document Object Model的简称，即文档数据模型。
Oracle公司提供了JAXP（Java API for XML Processing）来解析XML。JAXP会把XML文档转换成一个DOM树，JAXP的三个包都在JDK中。
org.w3c.dom;W3C推荐的解析文档的接口
org.xml.sax;使用SAX解析XML文档的接口
javax.xml.parsers;解析器工厂工具
一、使用DOM解析XML文档的步骤
1.创建解析器工厂对象，即DocumentBuilderFactory对象
2.由解析器工厂创建解析器对象，即DocumentBuilder对象
3.由解析器对象解析XML文档构建相应的DOM树，创建Document对象
4.以Document对象为起点对DOM树的节点进行增加、删除、修改、查询等操作
5.保存XML数据文档
二、案例
1 <?xml version="1.0" encoding="GB2312" standalone="no"?> 2 <PhoneInfo> 3 <Brand name="华为"> 4 <Type name="P9" /> 5 <Item> 6 <title>标题信息</title> 7 <link>连接</link> 8 <description>描述</description> 9 <pubDate>2016-11-12</pubDate> 10 </Item> 11 </Brand> 12 <Brand name="苹果"> 13 <Type name="iPhone5" /> 14 <Type name="iPhone6" /> 15 </Brand> 16 <Brand name="SAMSUNG"> 17 <Type name="Note7" /> 18 </Brand> 19 <Brand name="SAMSUNG"> 20 <Type name="Note7" /> 21 </Brand> 22 <Brand name="三星"> 23 <Type name="Note7" /> 24 </Brand> 25 <Brand name="三星"> 26 <Type name="Note7" /> 27 </Brand> 28 </PhoneInfo>
1.使用DOM读取手机收藏信息
1 import java.io.IOException; 2 3 import javax.xml.parsers.DocumentBuilder; 4 import javax.xml.parsers.DocumentBuilderFactory; 5 import javax.xml.parsers.ParserConfigurationException; 6 7 import org.w3c.dom.Document; 8 import org.w3c.dom.Element; 9 import org.w3c.dom.Node; 10 import org.w3c.dom.NodeList; 11 import org.xml.sax.SAXException; 12 13 /** 14 * DOM解析xml文档 15 * @author Administrator 16 * 17 */ 18 public class PhoneInfoShow { 19 20 public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException{ 21 //得到DOM解析器的工厂实例 22 DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 23 //从DOM工厂获得DOM解析器 24 DocumentBuilder builder = dbf.newDocumentBuilder(); 25 //解析xml文档，得到一个Document对象，即DOM树 26 Document phoneInfo = builder.parse("src/PhoneInfo.xml"); 27 //得到所有Brand节点列表信息 28 NodeList brandList = phoneInfo.getElementsByTagName("Brand"); 29 //循环Brand信息 30 for (int i = 0; i < brandList.getLength(); i++) { 31 //获取第i个Brand元素信息 32 Node node = brandList.item(i); 33 Element brand = (Element)node; 34 //获取元素属性值 35 String brandValue = brand.getAttribute("name"); 36 System.out.println("手机品牌："+brandValue); 37 //获取brand元素下的所有子元素 38 NodeList types = brand.getElementsByTagName("Type"); 39 for (int j = 0; j < types.getLength(); j++) { 40 /*Node item = types.item(j); 41 Element type = (Element)item;*/ 42 Element type = (Element)types.item(j); 43 //获取子节点属性值 44 String typeValue = type.getAttribute("name"); 45 System.out.println("\t型号："+typeValue); 46 } 47 } 48 } 49 50 }
2.查找节点信息
1 /** 2 * 查找节点信息 3 * @author Administrator 4 * 5 */ 6 public class PhoneInfo03{ 7 8 public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException { 9 //得到DOM解析器工厂 10 DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 11 //从DOM工厂获得DOM解析器 12 DocumentBuilder db = dbf.newDocumentBuilder(); 13 //解析XML文档得到一个DOM树 14 Document phoneInfo = db.parse(new File("src/PhoneInfo.xml")); 15 //读取pubDate 16 NodeList list = phoneInfo.getElementsByTagName("pubDate"); 17 //pubDate元素节点（转换） 18 Element pubDateElement = (Element)list.item(0); 19 //读取文本节点 20 String pubDate = pubDateElement.getFirstChild().getNodeValue(); 21 System.out.println(pubDate); 22 } 23 24 }
三、使用DOM维护XML数据
1.添加信息
1 import java.io.FileOutputStream; 2 import java.io.IOException; 3 4 import javax.xml.parsers.DocumentBuilder; 5 import javax.xml.parsers.DocumentBuilderFactory; 6 import javax.xml.parsers.ParserConfigurationException; 7 import javax.xml.transform.OutputKeys; 8 import javax.xml.transform.Transformer; 9 import javax.xml.transform.TransformerException; 10 import javax.xml.transform.TransformerFactory; 11 import javax.xml.transform.dom.DOMSource; 12 import javax.xml.transform.stream.StreamResult; 13 14 import org.w3c.dom.Document; 15 import org.w3c.dom.Element; 16 import org.xml.sax.SAXException; 17 18 /** 19 * 添加手机收藏信息 20 * @author Administrator 21 * 22 */ 23 public class PhoneInfoAdd { 24 25 public static void main(String[] args) throws TransformerException, SAXException, IOException, ParserConfigurationException { 26 //解析器工厂 27 DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 28 //解析器 29 DocumentBuilder db = dbf.newDocumentBuilder(); 30 //DOM文档 31 Document phone = db.parse("src/PhoneInfo.xml"); 32 /*创建brand节点*/ 33 Element brand = phone.createElement("Brand"); 34 brand.setAttribute("name","三星"); 35 /*创建type节点*/ 36 Element type = phone.createElement("Type"); 37 type.setAttribute("name", "Note7"); 38 //建立父子关系 39 brand.appendChild(type); 40 Element phoneElement = (Element)phone.getElementsByTagName("PhoneInfo").item(0); 41 phoneElement.appendChild(brand); 42 43 //保存xml文件 44 /*使用传输工厂*/ 45 TransformerFactory transformerFactory = TransformerFactory.newInstance(); 46 Transformer transformer = transformerFactory.newTransformer(); 47 /*创建数据源*/ 48 DOMSource domSource = new DOMSource(phone); 49 /*设置编码类型*/ 50 transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312"); 51 /*创建目标数据*/ 52 StreamResult result = new StreamResult(new FileOutputStream("src/PhoneInfo.xml")); 53 /*把DOM树转换为xml文件*/ 54 transformer.transform(domSource, result); 55 56 } 57 58 }
2.修改信息
1 import java.io.FileOutputStream; 2 import java.io.IOException; 3 4 import javax.xml.parsers.DocumentBuilder; 5 import javax.xml.parsers.DocumentBuilderFactory; 6 import javax.xml.parsers.ParserConfigurationException; 7 import javax.xml.transform.OutputKeys; 8 import javax.xml.transform.Result; 9 import javax.xml.transform.Transformer; 10 import javax.xml.transform.TransformerException; 11 import javax.xml.transform.TransformerFactory; 12 import javax.xml.transform.dom.DOMSource; 13 import javax.xml.transform.stream.StreamResult; 14 15 import org.w3c.dom.Document; 16 import org.w3c.dom.Element; 17 import org.w3c.dom.NodeList; 18 import org.xml.sax.SAXException; 19 20 public class PhoneInfoEdit { 21 22 public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, TransformerException { 23 //解析xml得到DOM对象 24 DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 25 DocumentBuilder db = dbf.newDocumentBuilder(); 26 Document phone = db.parse("src/PhoneInfo.xml"); 27 //找到修改的菜单 28 NodeList brand = phone.getElementsByTagName("Brand"); 29 for (int i = 0; i < brand.getLength(); i++) { 30 Element brandElement = (Element)brand.item(i); 31 //得到Brand的name属性 32 String brandName = brandElement.getAttribute("name"); 33 if ("三星".equals(brandName)) { 34 brandElement.setAttribute("name","SAMSUNG"); 35 } 36 } 37 //保存xml文件 38 TransformerFactory transformerFactory = TransformerFactory.newInstance(); 39 Transformer transformer = transformerFactory.newTransformer(); 40 /*创建DOM源*/ 41 DOMSource xmlSource = new DOMSource(phone); 42 /*设置编码类型*/ 43 transformer.setOutputProperty(OutputKeys.ENCODING,"gb2312"); 44 Result outputTarget = new StreamResult(new FileOutputStream("src/PhoneInfo.xml")); 45 //写入文件 46 transformer.transform(xmlSource, outputTarget ); 47 } 48 49 }
3.删除信息
1 import java.io.FileOutputStream; 2 import java.io.IOException; 3 4 import javax.xml.parsers.DocumentBuilder; 5 import javax.xml.parsers.DocumentBuilderFactory; 6 import javax.xml.parsers.ParserConfigurationException; 7 import javax.xml.transform.OutputKeys; 8 import javax.xml.transform.Result; 9 import javax.xml.transform.Transformer; 10 import javax.xml.transform.TransformerException; 11 import javax.xml.transform.TransformerFactory; 12 import javax.xml.transform.dom.DOMSource; 13 import javax.xml.transform.stream.StreamResult; 14 15 import org.w3c.dom.Document; 16 import org.w3c.dom.Element; 17 import org.w3c.dom.NodeList; 18 import org.xml.sax.SAXException; 19 20 /** 21 * 删除节点 22 * @author Administrator 23 * 24 */ 25 public class PhoneInfoDel { 26 27 public static void main(String[] args) throws SAXException, IOException, ParserConfigurationException, TransformerException { 28 //解析xml文档 29 DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance(); 30 DocumentBuilder documentBuilder = builderFactory.newDocumentBuilder(); 31 Document phone = documentBuilder.parse("src/PhoneInfo.xml"); 32 //找到要删除的节点 33 NodeList brand = phone.getElementsByTagName("Brand"); 34 //通过遍历Brand找到要删除的节点 35 for (int i = 0; i < brand.getLength(); i++) { 36 Element brandElement = (Element)brand.item(i); 37 //获取Brand节点属性 38 String brandName = brandElement.getAttribute("name"); 39 //查找需要的节点 40 if ("SAMSUNG".equals(brandName)) { 41 //获取父节点，利用父节点删除这个节点 42 brandElement.getParentNode().removeChild(brandElement); 43 } 44 } 45 /*for (int i = 0; i < brand.getLength(); i++) { 46 Element brandElement = (Element)brand.item(i); 47 //得到Brand的name属性 48 String brandName = brandElement.getAttribute("name"); 49 if ("三星".equals(brandName)) { 50 //修改属性 51 brandElement.setAttribute("name","SAMSUNG"); 52 //获取父节点，利用父节点删除这个节点 53 brandElement.getParentNode().removeChild(brandElement); 54 } 55 }*/ 56 //写入xml 57 TransformerFactory transformerFactory = TransformerFactory.newInstance(); 58 Transformer transformer = transformerFactory.newTransformer(); 59 DOMSource xmlSource = new DOMSource(phone); 60 //设置编码 61 transformer.setOutputProperty(OutputKeys.ENCODING,"gb2312"); 62 Result outputTarget = new StreamResult(new FileOutputStream("src/PhoneInfo.xml")); 63 transformer.transform(xmlSource, outputTarget); 64 /*TransformerFactory transformerFactory = TransformerFactory.newInstance(); 65 Transformer transformer = transformerFactory.newTransformer(); 66 创建DOM源 67 DOMSource xmlSource = new DOMSource(phone); 68 设置编码类型 69 transformer.setOutputProperty(OutputKeys.ENCODING,"gb2312"); 70 Result outputTarget = new StreamResult(new FileOutputStream("src/PhoneInfo.xml")); 71 //写入文件 72 transformer.transform(xmlSource, outputTarget );*/ 73 74 } 75 76 }
此外，还可以使用DOM4J解析XML文档会更加方便。
