菜鸟如何学习 XML （java）

 1 /构造一个XML解析器 并且创建新的文档/
 2 1     Document document = null;
 3 2         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
 4 3         try {
 5 4             DocumentBuilder builder = factory.newDocumentBuilder();
 6 5             document = builder.newDocument();//创建一个新的XML文件
 7 6             //document = builder.parse(fileName);//解析已存在的XML文件
 8 7         } catch (ParserConfigurationException e) {
 9 8             e.printStackTrace();
10 9         }

 1 //将内存中的xml，输出到文件上面
 2         Transformer tf = null;
 3         TransformerFactory tff = TransformerFactory.newInstance();
 4         try {
 5             tf = tff.newTransformer();
 6             tf.transform(new DOMSource(document), new StreamResult("src/test.xml"));
 7 
 8         } catch (TransformerConfigurationException e) {
 9             e.printStackTrace();
10         } catch (TransformerException e) {
11             e.printStackTrace();
12         }

 1         Element root = document.createElement("root");//创建根目录
 2         
 3         Element student = document.createElement("student");
 4         
 5         student.setAttribute("name", "xiaoming");//设置student 的属性值
 6         
 7         /*创建student的子元素*/
 8         Element id = document.createElement("id");
 9         Element sex = document.createElement("sex");
10         Element age = document.createElement("age");
11         
12         /*设置元素的文本*/
13         id.setTextContent("0001");
14         sex.setTextContent("man");
15         age.setTextContent("18");
16         
17         /*将子元素添加到父元素（student）中*/
18         student.appendChild(id);
19         student.appendChild(sex);
20         student.appendChild(age);
21         
22         root.appendChild(student);//将元素（节点）student 添加到根目录（root）中去
23         document.appendChild(root);//将根目录添加到文档中去

1 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
2 <root>
3     <student name="xiaoming">
4         <id>0001</id>
5         <sex>man</sex>
6         <age>18</age>
7     </student>
8 </root>

 1 <?xml version="1.0" encoding="UTF-8" standalone="no"?><root>
 2     <student name="xiaoming">
 3         <id>0001</id>
 4         <sex>man</sex>
 5         <age>18</age>
 6     </student>
 7     <student name="xiaozhu">
 8         <id>0002</id>
 9         <sex>man</sex>
10         <age>20</age>
11     </student>
12     <student name="xiaohong">
13         <id>0003</id>
14         <sex>female</sex>
15         <age>15</age>
16     </student>
17 </root>

 1 //获取student中属性name=xiaoming的所有信息
 2         NodeList list_st =document.getElementsByTagName("student");
 3         /*遍历所有student的元素*/
 4         for(int i=0;i<list_st.getLength();i++)
 5         {
 6             Node n =list_st.item(i);
 7             
 8             Element student= (Element)n;//必须强转为元素才能获取到设置的属性，节点获取不了属性
 9             
10             /*找出student中属性xiaoming的节点*/
11             if(student.getAttribute("name").equals("xiaoming"))
12             {
13                 /*获取所有标签中的文本信息*/
14                 String id = student.getElementsByTagName("id").item(0).getTextContent();
15                 String sex = student.getElementsByTagName("sex").item(0).getTextContent();
16                 String age = student.getElementsByTagName("age").item(0).getTextContent();
17                 
18                 System.out.println("id:"+id);
19                 System.out.println("sex:"+sex);
20                 System.out.println("age:"+age);
21                 /*输出：
22                  * id:0001
23                  * sex:man
24                  * age:18
25                  */
26             }
27         }