【Java】Java 中实现深拷贝

浅拷贝 和 深拷贝

浅拷贝：只复制一层，如果对象的属性是引用数据类型，只会复制属性内存地址。
深拷贝：不只复制一层，如果对象属性是引用数据类型，会继续向下进行复制。

深拷贝的实现方法

1. 实现 Cloneable 接口

Artist.class

public class Artist implements Cloneable{
    /**
     * 姓名
     */
    private String name;
    /**
     * 年龄
     */
    private int age;

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

    @Override
    public Artist clone() {
        try {
            Artist clone = (Artist) super.clone();
            // TODO: copy mutable state here, so the clone can't change the internals of the original
            return clone;
        } catch (CloneNotSupportedException e) {
            throw new AssertionError();
        }
    }
}

Music.class

public class Music implements Cloneable{
    /**
     * 音乐名称
     */
    private String title;
    /**
     * 所属专辑
     */
    private String album;
    /**
     * 作曲人
     */
    private Artist artist;

    public Music(String title, String album, Artist artist) {
        this.title = title;
        this.album = album;
        this.artist = artist;
    }

    @Override
    public Music clone() {
        try {
            Music clone = (Music) super.clone();
            // TODO: copy mutable state here, so the clone can't change the internals of the original
            clone.artist = this.artist.clone();
            return clone;
        } catch (CloneNotSupportedException e) {
            throw new AssertionError();
        }
    }
}

Music 类中的 artist 属性是 Artist类，Music 和 Artist 都要实现 Cloneable 接口，并且重写 clone() 方法

2. 序列化

每一个背拷贝的类都要实现 Serializable 接口

//深度拷贝
public Object deepClone() throws Exception{
    // 序列化
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(bos);

    oos.writeObject(this);

    // 反序列化
    ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
    ObjectInputStream ois = new ObjectInputStream(bis);

    return ois.readObject();
}

参考：https://www.cnblogs.com/ysocean/p/8482979.html