Java学习路线-45：XML快速入门（2）-dom4j、XPATH、应用案例

第5 章 ： XML解析之dom4j

课时31 dom4j的简介

https://dom4j.github.io/
依赖

<dependency>
    <groupId>org.dom4j</groupId>
    <artifactId>dom4j</artifactId>
    <version>2.0.0</version>
</dependency>

demo.xml

<?xml version="1.0" encoding="UTF-8"?>

<list> 
  <person> 
    <name>张三</name>  
    <age>23</age> 
  </person>  
  <person> 
    <name>李四</name>  
    <age>24</age> 
  </person> 
</list>

课时32 使用dom4j实现查询xml操作

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import java.util.List;

class Demo {

    public static void main(String[] args) throws DocumentException {
        // 创建解析器
        SAXReader reader = new SAXReader();

        // 得到Document
        Document document = reader.read("demo.xml");

        // 获取根元素
        Element root = document.getRootElement();

        // 得到所有person标签
        List<Element> list = root.elements("person");

        // 遍历标签
        for (Element element : list) {
            Element name = element.element("name");

            // 获取值
            String text = name.getText();
            System.out.println(text);
        }
    }
}

课时33 使用dom4j实现在末尾添加节点的操作

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

import java.io.FileOutputStream;
import java.io.IOException;

class Demo {

    public static void main(String[] args) throws DocumentException, IOException {
        // 创建解析器， 得到Document
        SAXReader reader = new SAXReader();
        Document document = reader.read("demo.xml");

        // 获取根元素
        Element root = document.getRootElement();

        // 添加元素并设置内容
        Element person = root.element("person");
        Element sex = person.addElement("sex");
        sex.setText("男");

        // 回写并格式化
        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter xmlWriter = new XMLWriter(new FileOutputStream("demo.xml"), format);
        xmlWriter.write(document);
        xmlWriter.close();
    }
}

课时34 使用dom4j实现在在特定位置添加节点的操作

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;

class Demo {

    public static void main(String[] args) throws DocumentException, IOException {
        // 创建解析器， 得到Document
        SAXReader reader = new SAXReader();
        Document document = reader.read("demo.xml");
        Element root = document.getRootElement();

        // 指定位置添加元素
        Element person = root.element("person");
        List<Element> list = person.elements();
        Element sex = DocumentHelper.createElement("sex");
        sex.setText("女");
        list.add(1, sex);

        // 回写并格式化
        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter xmlWriter = new XMLWriter(new FileOutputStream("demo.xml"), format);
        xmlWriter.write(document);
        xmlWriter.close();
    }
}

课时35 dom4j里面封装方法的操作

package util;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

import java.io.FileOutputStream;
import java.io.IOException;

public class Dom4jUtil {
    public static Document getDocument(String path) throws DocumentException {
        // 创建解析器， 得到Document
        SAXReader reader = new SAXReader();
        return reader.read(path);
    }

    public static void writeXml(String path, Document document) throws IOException {
        // 回写并格式化
        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(path), format);
        xmlWriter.write(document);
        xmlWriter.close();
    }
}

课时36 使用dom4j实现修改的操作

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import util.Dom4jUtil;

import java.io.IOException;

class Demo {

    public static void main(String[] args) throws DocumentException, IOException {
        // 创建解析器， 得到Document
        String path = "demo.xml";
        Document document = Dom4jUtil.getDocument(path);

        // 获取根元素
        Element root = document.getRootElement();

        Element peron = root.element("person");
        Element sex = peron.element("sex");
        sex.setText("男");

        // 回写并格式化
        Dom4jUtil.writeXml(path, document);
    }
}

课时37 使用dom4j实现删除节点的操作

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import util.Dom4jUtil;

import java.io.IOException;

class Demo {

    public static void main(String[] args) throws DocumentException, IOException {
        String path = "demo.xml";
        Document document = Dom4jUtil.getDocument(path);

        // 获取根元素
        Element root = document.getRootElement();
        Element person = root.element("person");
        Element sex = person.element("sex");

        // 通过父节点删除
        sex.getParent().remove(sex);

        // 回写并格式化
        Dom4jUtil.writeXml(path, document);
    }
}

课时38 使用dom4j实现获取属性值的操作

demo.xml

<?xml version="1.0" encoding="UTF-8"?>

<person id="001">
    <name>张三</name>
    <age>23</age>
</person>

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import util.Dom4jUtil;

import java.io.IOException;

class Demo {

    public static void main(String[] args) throws DocumentException, IOException {
        String path = "demo.xml";
        Document document = Dom4jUtil.getDocument(path);

        Element root = document.getRootElement();
        String id = root.attributeValue("id");
        System.out.println(id); // 001

    }
}

第6 章 ： XPATH

课时39 XPATH简介

dom4j支持xpath操作

可以直接获取元素

/a/b/c             一层一层选择
//b                不管层级，直接选择b
/*                 所有元素
/a/b[1]            第一个b元素
/a/b[last()]       最后一个b元素
//b[@id]           只要有id属性 
//b[@name="bbb"]   name属性等于bbb

课时40 使用dom4j支持XPATH的操作一

jaxen

selectNode()
selectSingleNode()

demo.xml

<?xml version="1.0" encoding="UTF-8"?>

<person id="001">
    <name>张三</name>
    <age>23</age>
</person>

示例：得到所有name节点

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Node;
import util.Dom4jUtil;

import java.util.List;

class Demo {

    public static void main(String[] args) throws DocumentException {
        String path = "demo.xml";
        Document document = Dom4jUtil.getDocument(path);

        // 获取元素
        List<Node> list = document.selectNodes("//name");

        // 遍历集合
        for (Node node : list) {
            String text = node.getText();
            System.out.println(text);
        }

    }
}

课时41 使用dom4j支持XPATH的操作二

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Node;
import util.Dom4jUtil;

class Demo {

    public static void main(String[] args) throws DocumentException {
        String path = "demo.xml";
        Document document = Dom4jUtil.getDocument(path);

        // 获取根元素
        Node name = document.selectSingleNode("/person[@id='001']/name");
        System.out.println(name.getText());
    }
}

第7 章 ： 案例

课时42-44 学生管理系统实现-添加、删除、查询操作

使用xml作为数据库，存储学生数据

依赖

<dependency>
    <groupId>org.dom4j</groupId>
    <artifactId>dom4j</artifactId>
    <version>2.0.0</version>
</dependency>

demo.xml

<?xml version="1.0" encoding="UTF-8"?>

<list>

</list>

Dom4jUtil.java

package util;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

import java.io.FileOutputStream;
import java.io.IOException;

public class Dom4jUtil {
    public static Document getDocument(String path) throws DocumentException {
        // 创建解析器， 得到Document
        SAXReader reader = new SAXReader();
        return reader.read(path);
    }

    public static void writeXml(String path, Document document) throws IOException {
        // 回写并格式化
        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(path), format);
        xmlWriter.write(document);
        xmlWriter.close();
    }

}

Student.java

package com.pengshiyu.student;

public class Student {
    private String id;
    private String name;
    private int age;

    public Student() {
    }

    public Student(String id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }


    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

StudentService.java

package com.pengshiyu.student;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import util.Dom4jUtil;

import java.io.IOException;
import java.util.List;

public class StudentService {
    private static final String path = "demo.xml";

    /**
     * 添加数据
     *
     * @param student
     * @throws DocumentException
     * @throws IOException
     */
    public static void addStudent(Student student) throws DocumentException, IOException {
        Document document = Dom4jUtil.getDocument(path);
        Element root = document.getRootElement();

        Element person = root.addElement("person");

        Element id = person.addElement("id");
        id.setText(student.getId());

        Element name = person.addElement("name");
        name.setText(student.getName());

        Element age = person.addElement("age");
        age.setText(String.valueOf(student.getAge()));

        Dom4jUtil.writeXml(path, document);
    }

    /**
     * 删除数据
     *
     * @param uid
     * @throws IOException
     * @throws DocumentException
     */
    public static void removeStudent(String uid) throws IOException, DocumentException {
        Document document = Dom4jUtil.getDocument(path);

        // 获取所有的id
        List<Node> list = document.selectNodes("//id");
        for (Node node : list) {
            String nodeId = node.getText();
            // System.out.println(nodeId);

            // 判断id相同，通过祖父节点移除父节点
            if (uid.equals(nodeId)) {
                Element parent = node.getParent();
                Element grandfather = parent.getParent();
                grandfather.remove(parent);
            }
        }
        Dom4jUtil.writeXml(path, document);
    }

    /**
     * 查询数据
     *
     * @param uid
     * @return
     * @throws IOException
     * @throws DocumentException
     */
    public static Student getStudent(String uid) throws DocumentException {
        Document document = Dom4jUtil.getDocument(path);

        // 获取所有的id
        List<Node> list = document.selectNodes("//id");
        for (Node node : list) {
            String nodeId = node.getText();
            // System.out.println(nodeId);

            // 判断id相同，通过祖父节点移除父节点
            if (uid.equals(nodeId)) {
                Element parent = node.getParent();

                Student student = new Student();
                student.setId(parent.element("id").getText());
                student.setName(parent.element("name").getText());
                student.setAge(Integer.parseInt(parent.element("age").getText()));

                return student;
            }
        }
        return null;
    }
}

StudentTest.java

package com.pengshiyu.student;

import org.dom4j.DocumentException;
import org.junit.Test;

import java.io.IOException;

public class StudentTest {

    @Test
    public void testAddStudent() throws IOException, DocumentException {
        Student student = new Student("001", "Tom", 23);
        StudentService.addStudent(student);
    }

    @Test
    public void testRemoveStudent() throws IOException, DocumentException {
        StudentService.removeStudent("001");
    }

    @Test
    public void testGEtStudent() throws IOException, DocumentException {
        Student student= StudentService.getStudent("001");
        System.out.println(student);
    }
}