/**
 * @author CSZ
 * @create 2021-04-2021/4/9 14:31
 */

class Man{
    private int hands;
    private String eyes;
    private int legs;
    private String head;

    public Man() {
    }

    public Man(int hands, String eyes, int legs, String head) {
        this.hands = hands;
        this.eyes = eyes;
    }

    public int getHands() {
        return hands;
    }

    public void setHands(int hands) {
        this.hands = hands;
    }

    public String getEyes() {
        return eyes;
    }

    public void setEyes(String eyes) {
        this.eyes = eyes;
    }
}

class Woman{
    private int children;

    public Woman() {
    }

    public Woman(int children) {
        this.children = children;
    }

    public void setChildren(int children){
        this.children = children;
    }

    public int getChildren(){
        return children;
    }
}

class Human{
    Man man;
    Woman woman;

    public Man getMan() {
        return man;
    }

    public void setMan(Man man) {
        this.man = man;
    }

    public Woman getWoman() {
        return woman;
    }

    public void setWoman(Woman woman) {
        this.woman = woman;
    }

    public Human(Man man, Woman woman) {
        this.man = man;
        this.woman = woman;
    }
}
public class ObjectTest {
    public static void main(String[] args) {

        Human human = new Human(new Man(), new Woman());// 新建了一个 human
        Man man = human.getMan(); // 获取human 中的 man
        System.out.println("打印对象地址" + man);
        System.out.println("设置属性");
        man.setEyes("两只大眼睛"); // 设置了属性 但是地址引用还是同一个
        System.out.println("再次打印地址值" + man);
        System.out.println(human.getMan().getEyes());

        System.out.println("==================================================");

        Human human1 = new Human(new Man(),new Woman());
        System.out.println("新创建的human1 " + human1);
        Woman woman = new Woman(50);
        System.out.println("新创建的woman1 "+ woman);
        System.out.println("human1中的Woman" + human1.getWoman());
        System.out.println("将新创建的对象保存到human1中");
        human1.setWoman(woman);
        System.out.println("更新信息后human1 "+human1);
        System.out.println(human1.getWoman().getChildren());
    }
}

在注入时有两种方式：

1. 通过获取到实例对象，修改对象的属性，再用Human 获取内部信息，同理啊，也可能时保存操作，save()。
2. 通过创建一个新的实例对象，通过调用 Human的set方法，也可以实现，对Human的修改。