动物园新进了3头大象：

胖胖，2岁，1.2吨；

肥仔，1岁，1.5吨；

憨憨，3岁，1.8吨；

还有3只猴子：

星仔，3岁，0.8米；

狒狒，4岁，0.9米；

猴哥，5岁，1.0米；

它们的信息存在了集合中，现在动物管理员需要将这些宝贝们的信息存入xml中保存.请你写一个程序，结合面向对象，和dom4j技术，帮管理员实现这个功能。

1.首先创建动物类作为父类

public class Animal {
    private String name;
    private int age;

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

    public Animal() {
    }

    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;
    }
}

2.再创建两个子类

大象类（Elephant）

public class Elephant extends Animal{
    private double weight;

    public Elephant() {
    }

    public Elephant(double weight) {
        this.weight = weight;
    }

    public Elephant(String name, int age, double weight) {
        super(name, age);
        this.weight = weight;
    }

    public double getWeight() {
        return weight;
    }

    public void setWeight(double weight) {
        this.weight = weight;
    }
}

猴子类（Monkey）

public class Monkey extends Animal {
    private double height;

    public Monkey() {
    }

    public Monkey(double height) {
        this.height = height;
    }

    public Monkey(String name, int age, double height) {
        super(name, age);
        this.height = height;
    }

    public double getHeight() {
        return height;
    }

    public void setHeight(double height) {
        this.height = height;
    }
}

3.最后测试类

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

import java.io.*;
import java.util.ArrayList;

public class AnimalTest {
    public static void main(String[] args) throws Exception{
        ArrayList<Animal> animals = new ArrayList<>();
        animals.add(new Elephant("胖胖",2,1.2));
        animals.add(new Elephant("肥仔",1,1.5));
        animals.add(new Elephant("猪哥",3,1.8));
        animals.add(new Monkey("星仔",3,0.8));
        animals.add(new Monkey("狒狒",4,0.9));
        animals.add(new Monkey("猴哥",5,1.0));
        Xmlcreat(animals);
    }

    public static void Xmlcreat(ArrayList<Animal> animals) throws IOException {
        //创建DOM数
        Document document = DocumentHelper.createDocument();
        //添加根节点
        Element animals1 = document.addElement("animals");
        //遍历集合
        for (int i = 0; i < animals.size(); i++) {
            //添加子节点
            Element animal = animals1.addElement("animal");
            //再给子节点添加子节点
            Element name = animal.addElement("name");
            name.setText(animals.get(i).getName());
            Element age = animal.addElement("age");
            age.setText(animals.get(i).getAge()+"岁");
            //判断是大象还是猴子
            if (animals.get(i) instanceof Elephant){
                Element weight = animal.addElement("weight");
                weight.setText(((Elephant)animals.get(i)).getWeight()+"吨");
            }else{
                Element height = animal.addElement("height");
                height.setText(((Monkey)animals.get(i)).getHeight()+"米");
            }
        }

        //写入xml中
//        FileOutputStream out = new FileOutputStream("/src/day22/HomeWork.xml");
//        OutputFormat format = OutputFormat.createPrettyPrint();
//        XMLWriter writer = new XMLWriter(out, format);
//        writer.write(document);
//        writer.close();
        String s = System.getProperty("user.dir") + "/src/day22/HomeWork.xml";
        FileWriter fileWriter = new FileWriter(s);
        document.write(fileWriter);
        fileWriter.close();
    }
}

运行完成以后查看xml文档