// 课程对象
class Class {
  private String name;

  public String getName() {
    return name;
  }

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

}
// 学生对象
class User implements Cloneable {
  private String name;
  private Long id;
  // 课程引用
  private Class c;

  public Class getC() {
    return c;
  }

  public void setC(Class c) {
    this.c = c;
  }

  public String getName() {
    return name;
  }

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

  public Long getId() {
    return id;
  }

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

  @Override
  protected Object clone() throws CloneNotSupportedException {
    return super.clone();
  }

  @Override
  public int hashCode() {
    return super.hashCode();
  }

  @Override
  public boolean equals(Object obj) {

    if (obj instanceof User) {
      User user = (User) obj;
      if (this.id == user.getId() && this.getName() == user.getName()) {
        return true;
      }
      if (user.getId().equals(this.id)
          && user.getName().equals(this.name)) {
        return true;
      }
      return false;
    } else
      return false;
  }

}

 User user1 = new User();
    User user2 = user1;

    User user3 = (User) user1.clone();

    System.out.println(user1 == user2);
    System.out.println(user3 == user1);
    System.out.println(user3.equals(user1));
    System.out.println(user3.getName() == user3.getName());// true，浅复制

    Class c = new Class();
    c.setName("语文");
    user1.setC(c);
    // 测试复制深度
    User user4 = (User) user1.clone();
    System.out.println(user4.getC() == user1.getC()); // true,说明引用的对象依然是同一个对象

class Car implements Serializable {
  /**
   * 
   */
  private static final long serialVersionUID = 42342L;
  private String name;

  public String getName() {
    return name;
  }

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

}

// 深复制
class People implements Serializable{
  /**
   * 
   */
  private static final long serialVersionUID = 543535212412L;
  private Car car;

  public Car getCar() {
    return car;
  }

  public void setCar(Car car) {
    this.car = car;
  }

  public People deepClone() throws IOException, ClassNotFoundException {
    // 腌制
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(out);
    oos.writeObject(this);
    // 取出
    ByteArrayInputStream input = new ByteArrayInputStream(out.toByteArray());
    ObjectInputStream ois = new ObjectInputStream(input);
    return (People) ois.readObject();
  }

}

// 深复制
    Car car = new Car();
    car.setName("benz");
    People p = new People();
    p.setCar(car);

    try {
      People p2 = p.deepClone();
      System.out.println(p2.getCar() == p.getCar()); // false,说明引用的对象也进行了复制
    } catch (ClassNotFoundException | IOException e) {
      e.printStackTrace();
    }