Java——使用DOM4j解析XML文档
【Java——使用DOM4j解析XML文档】DOM4J是一个第三方的XML解析开发包，可以很方便的对XML文件进行增删改查等操作，可以在其开发文档中快速掌握使用方法。
- 简单使用
package com.keixn.day3;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Iterator;
import java.util.Scanner;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
/**
* 使用DOM4j解析XML文件 需要用时查阅DOM4j使用文档/docs/index.html
*
* @author KeXin
*
*/
public class Demo1 {
// 创建解析器返回DOCUMENT对象
public Document parse(File url) throws DocumentException {
SAXReader reader = new SAXReader();
Document document = reader.read(url);
return document;
}// Writing a document to a file
public void write(Document document) throws IOException {
// lets write to a file
XMLWriter writer = new XMLWriter(new FileWriter("src/com/keixn/day3/stu_info.xml"));
writer.write(document);
writer.close();
}
// Creating a new XML node
public Element createElement(String examid,String idcard,String name,String location,String grade) {
Element stu = DocumentHelper.createElement("stu").addAttribute("examid", examid).addAttribute("idcard", idcard);
Element name_node = stu.addElement("name").addText(name);
Element location_node = stu.addElement("location").addText(location);
Element grade_node = stu.addElement("grade").addText(grade);
return stu;
}
//Update a XML node
public void UpdateElement(Document document) throws IOException{
Element root = document.getRootElement();
System.out.println("请输入学生身份证号：");
Scanner scan = new Scanner(System.in);
String idcard = scan.nextLine();
for ( Iterator i = root.elementIterator( "stu" );
i.hasNext();
) {
Element stu = (Element) i.next();
if(stu.attributeValue("idcard").equals(idcard)){
System.out.println("已经查到该学生，请输入他的成绩：");
String grade = scan.nextLine();
stu.element("grade").setText(grade);
this.write(document);
System.out.println("更新成功");
return;
}
}
System.out.println("查无此人");
}
public static void main(String[] args) throws DocumentException, IOException {
Demo1 demo = new Demo1();
Document document = demo.parse(new File("src/com/keixn/day3/stu_info.xml"));
Element root = document.getRootElement();
Element stu = demo.createElement("000", "122", "lisa", "北京", "86");
root.add(stu);
demo.write(document);
System.out.println();
demo.UpdateElement(document);
}}
2.作业：用XML文件模拟数据库，使用DOM4j对学生数据进行增删改查。
package com.keixn.day3;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URL;
import java.util.Iterator;
import java.util.Scanner;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
public class StuTask {
private final String xml_path = "src/com/keixn/day3/stu_info.xml";
private final String STU = "stu", EXAM = "exam", EXAMID = "examid", IDCARD = "idcard", NAME = "name",
LOCATION = "location", GRADE = "grade";
/*
* 添加新用户
*/
public void AddStu() throws IOException, DocumentException {
Student stu = new Student();
Scanner s1 = new Scanner(System.in);
System.out.println("请输入学生姓名");
stu.setName(s1.nextLine());
System.out.println("请输入准考证号");
stu.setExamid(s1.nextLine());
System.out.println("请输入身份证号");
stu.setIdcard(s1.nextLine());
System.out.println("请输入学生地址");
stu.setLocation(s1.nextLine());
System.out.println("请输入学生成绩");
stu.setGrade(s1.nextLine());
Document document = this.GetDocument(new File(xml_path));
Element root = document.getRootElement();
// 创建stu标签
Element stu_node = root.addElement(STU).addAttribute(IDCARD, stu.getIdcard()).addAttribute(EXAMID,
stu.getExamid());
// 创建stu标签内的name location grade标签
Element stu_name_node = stu_node.addElement(NAME);
stu_name_node.setText(stu.getName());
Element stu_location_node = stu_node.addElement(LOCATION);
stu_location_node.setText(stu.getLocation());
Element stu_grade_node = stu_node.addElement(GRADE);
stu_grade_node.setText(stu.getGrade());
this.SvaeToXML(document);
System.out.println("添加成功");
}/*
* 删除用户
*/
public void DeleteStu() throws IOException, DocumentException {
System.out.println("请输入准考证号");
Scanner s1 = new Scanner(System.in);
String examid = s1.nextLine();
Document document = this.GetDocument(new File(xml_path));
Element root = document.getRootElement();
Iterator iterator = root.elementIterator(STU);
Element e;
while(iterator.hasNext()){
e = (Element) iterator.next();
if(e.attributeValue(EXAMID).equals(examid)){
root.remove(e);
this.SvaeToXML(document);
System.out.println("删除成功");
return;
}
}
System.out.println("查无此人");
}/*
* 查询成绩
*/
public void QuestStu() throws IOException, DocumentException {
System.out.println("请输入准考证号");
Scanner s1 = new Scanner(System.in);
String examid = s1.nextLine();
Document document = this.GetDocument(new File(xml_path));
Element root = document.getRootElement();
Iterator iterator = root.elementIterator(STU);
Element e;
while(iterator.hasNext()){
e = (Element) iterator.next();
if(e.attributeValue(EXAMID).equals(examid)){
System.out.println(e.elementText(GRADE));
return;
}
}
System.out.println("查无此人");
}public Document GetDocument(File url) throws DocumentException {
SAXReader reader = new SAXReader();
Document document = reader.read(url);
return document;
}public static void main(String[] args) throws IOException, DocumentException {
int key = 0;
StuTask st = new StuTask();
Scanner scan = new Scanner(System.in);
System.out.println("请选择操作：");
while (key != 4) {
System.out.println("1、添加新用户；2、删除用户；3、查询成绩；4、退出系统");
key = scan.nextInt();
switch (key) {
case 1:
st.AddStu();
break;
case 2:
st.DeleteStu();
break;
case 3:
st.QuestStu();
break;
default:
key = 4;
}
}
}/*
* 将document输出至xml文件
*/
public void SvaeToXML(Document document) throws IOException {
XMLWriter writer = new XMLWriter(new FileWriter("src/com/keixn/day3/stu_info.xml"));
writer.write(document);
writer.close();
}
}
Student.java:
package com.keixn.day3;
public class Student {
private String idcard;
private String examid;
private String name;
private String location;
private String grade;
public String getIdcard() {
return idcard;
}public void setIdcard(String idcard) {
this.idcard = idcard;
}public String getExamid() {
return examid;
}public void setExamid(String examid) {
this.examid = examid;
}public String getName() {
return name;
}public void setName(String name) {
this.name = name;
}public String getLocation() {
return location;
}public void setLocation(String location) {
this.location = location;
}public String getGrade() {
return grade;
}public void setGrade(String grade) {
this.grade = grade;
}public String GetStu(Student stu) {
String result = "";
if (stu != null) {
result+=stu.getName()+"\t"+stu.getExamid()+"\t"+stu.getIdcard()+"\t"+stu.getLocation()+"\t"+stu.getGrade();
}return result;
}}stu_info.xml:
lisa
北京
78
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