问题
解析如下格式的xml文件
<?xml version="1.0" encoding="UTF-8" standalone="no"?><exam>
<student examid="111" idcard="123">
<name>张三</name>
<location>广州</location>
<grade>100</grade>
</student>
<student examid="444" idcard="333">
<name>李四</name>
<location>大连</location>
<grade>97</grade>
</student>
<student examid="1111111" idcard="22222">
<name>小毛</name>
<location>广州</location>
<grade>23.0</grade>
</student>
<student examid="199" idcard="300">
<grade>80.0</grade>
<location>广州</location>
<name>钟源茂</name>
</student>
</exam>
解决
根据数据，定义类对象用于存储
@Getter
@Setter
class Student{
private String name;
private String examid;
private String idcart;
private String location;
private String grade;
@Override
public String toString(){
return "姓名：" + name + ", 身份证号：" + idcart + ", 准考证号：" + examid + ", 地区：" + location + ", 成绩：" + grade;
}
}
解析xml数据
public class JaxpSimpleDemo {
private static Student find() throws Exception {
Document document = getDocument();
NodeList list = document.getElementsByTagName("student");
for (int i = 0; i < list.getLength(); i++) {
Element element = (Element) list.item(i);
Student student = new Student();
student.setExamid(element.getAttribute("examid"));
student.setIdcart(element.getAttribute("idcard"));
student.setName(element.getElementsByTagName("name").item(0).getTextContent());
student.setLocation(element.getElementsByTagName("location").item(0).getTextContent());
student.setGrade(element.getElementsByTagName("grade").item(0).getTextContent());
System.out.println(student);
}
return null;
}
private static Document getDocument() throws ParserConfigurationException,
IOException, org.xml.sax.SAXException {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("/Users/***/exam.xml"));
Element e = document.getDocumentElement();
return document;
}
public static void main(String[] args) throws Exception {
find();
}
结果
姓名：张三, 身份证号：123, 准考证号：111, 地区：广州, 成绩：100
姓名：李四, 身份证号：333, 准考证号：444, 地区：大连, 成绩：97
姓名：小毛, 身份证号：22222, 准考证号：1111111, 地区：广州, 成绩：23.0
姓名：钟源茂, 身份证号：300, 准考证号：199, 地区：广州, 成绩：80.0
解析
<student>里面有两类数据：一是成员变量、一是标签，分别用以下获取
- element.getAttribute("idcard")
- element.getElementsByTagName("name").item(0).getTextContent()
拓展
增删改查
package xmlparse;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
public class JaxpDemo {
public static void main(String[] args) throws Exception {
System.out.print("添加用户：a ");
System.out.print("删除用户：b ");
System.out.println("查询成绩：c");
System.out.print("请输入操作类型：");
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String type = br.readLine();
if ("a".equals(type)) {
//添加用户
Student student = new Student();
System.out.print("请输入学生姓名：");
String name = br.readLine();
student.setName(name);
System.out.print("请输入学生准考证号：");
String examid = br.readLine();
student.setExamid(examid);
System.out.print("请输入学生身份证号：");
String idcard = br.readLine();
student.setIdcart(idcard);
System.out.print("请输入学生所在地：");
String location = br.readLine();
student.setLocation(location);
System.out.print("请输入学生成绩：");
String grade = br.readLine();
student.setGrade(grade);
add(student);
System.out.println("------添加数据成功------");
} else if ("b".equals(type)) {
//删除用户
System.out.print("请输入删除的学生姓名：");
String name = br.readLine();
delete(name);
System.out.println("------已成功删除学生信息------");
} else if ("c".equals(type)) {
//查询成绩
System.out.print("请输入查询的学生准考证号：");
String examid = br.readLine();
Student student = find(examid);
System.out.println("您查询的学生信息为：");
System.out.println(student);
} else {
System.out.println("对不起，您的操作有误！！");
}
}
private static Student find(String examid) throws Exception {
Document document = getDocument();
NodeList list = document.getElementsByTagName("student");
for (int i = 0; i < list.getLength(); i++) {
Element element = (Element) list.item(i);
String value = element.getAttribute("examid");
if (examid.equals(value)) {
Student student = new Student();
student.setExamid(examid);
student.setIdcart(element.getAttribute("idcard"));
student.setName(element.getElementsByTagName("name").item(0).getTextContent());
student.setLocation(element.getElementsByTagName("location").item(0).getTextContent());
student.setGrade(element.getElementsByTagName("grade").item(0).getTextContent());
return student;
}
}
return null;
}
private static void delete(String name) throws ParserConfigurationException, IOException, TransformerException, org.xml.sax.SAXException {
Document document = getDocument();
NodeList list = document.getElementsByTagName("name");
for (int i = 0; i < list.getLength(); i++) {
Node node = list.item(i);
if (node.getTextContent().equals(name)) {
node.getParentNode().getParentNode().removeChild(node.getParentNode());
}
}
writeXml(document);
}
private static void add(Student student) throws Exception {
Document document = getDocument();
Element studentNode = document.createElement("student");
studentNode.setAttribute("idcard", student.getIdcart());
studentNode.setAttribute("examid", student.getExamid());
Node name = document.createElement("name");
name.setTextContent(student.getName());
Node location = document.createElement("location");
location.setTextContent(student.getLocation());
Node grade = document.createElement("grade");
grade.setTextContent(student.getGrade());
studentNode.appendChild(name);
studentNode.appendChild(location);
studentNode.appendChild(grade);
Element root = document.getDocumentElement();
root.appendChild(studentNode);
writeXml(document);
}
//将内存中的数据保存到XML文件中
private static void writeXml(Document document) throws TransformerException {
DOMSource source = new DOMSource(document);
StreamResult result = new StreamResult(new File("src/exam.xml"));
TransformerFactory factory = TransformerFactory.newInstance();
Transformer trans = factory.newTransformer();
trans.transform(source, result);
}
//获得操作xml文件的对象
private static Document getDocument() throws ParserConfigurationException,
IOException, org.xml.sax.SAXException {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();//得到创建 DOM 解析器的工厂。
DocumentBuilder builder = factory.newDocumentBuilder();//得到 DOM 解析器对象。
Document document = builder.parse(new File("/Users/wzh94434/Code/codetest/javalearntest/src/main/java/xmlparse/exam.xml")); //得到代表整个文档的 Document 对象
Element e = document.getDocumentElement();
return document;
}
}