DOM的概念和简单应用：使用DOM解析XML数据

Posted 2020-09-19 滕秋宇

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。