Java的深拷贝与浅拷贝的几种实现方式

 A a = new A();
 A b = a;

public class Student{
 private String name; 
 private int age;  
 private String sex; 
}


public class School {
 private String schoolName;
 private int stuNums;
 private Student stu;
}

public class Student{
  private String name;
  private int age;
  private String sex;
  
  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;
  }
  public String getSex() {
    return sex;
  }
  public void setSex(String sex) {
    this.sex = sex;
  }
  @Override
  public String toString() {
    return "Student [name=" + name + ", age=" + age + ", sex=" + sex + "]";
  }
}

public class School implements Cloneable{
  private String schoolName;
  private int stuNums;
  private Student stu;
  
  public String getSchoolName() {
    return schoolName;
  }
  public void setSchoolName(String schoolName) {
    this.schoolName = schoolName;
  }
  public int getStuNums() {
    return stuNums;
  }
  public void setStuNums(int stuNums) {
    this.stuNums = stuNums;
  }
  public Student getStu() {
    return stu;
  }
  public void setStu(Student stu) {
    this.stu = stu;
  }
  @Override
  protected School clone() throws CloneNotSupportedException {
    // TODO Auto-generated method stub
    return (School)super.clone();
  }
  @Override
  public String toString() {
    return "School [schoolName=" + schoolName + ", stuNums=" + stuNums + ", stu=" + stu + "]";
  }
}

public class TestClone {
  public static void main(String[] args) throws CloneNotSupportedException {
    //创建初始的School对象
    School s1 = new School();
    s1.setSchoolName("xx大学");
    s1.setStuNums(2000);
    Student stu1 = new Student();
    stu1.setAge(20);
    stu1.setName("肉丁");
    stu1.setSex("女");
    s1.setStu(stu1);
    School s2 = s1.clone(); //调用重写的clone方法，clone出一个新的school---s2
    System.out.println("s1: "+s1+" s1的hashcode:"+s1.hashCode()+" s1中stu1的hashcode:"+s1.getStu().hashCode());
    System.out.println("s2: "+s2+" s2的hashcode:"+s2.hashCode()+" s2中stu1的hashcode:"+s2.getStu().hashCode());//System.out.println(s1.getStu().getAge()==s2.getStu().getAge());
    System.out.println("----------------------------");
    System.out.println("修改克隆出来的对象");
    Student student2 = s2.getStu();
    student2.setAge(21);
    student2.setName("斌");
    s2.setStu(student2);
    System.out.println("s1: "+s1+" s1的hashcode:"+s1.hashCode()+" s1中stu1的hashcode:"+s1.getStu().hashCode());
    System.out.println("s2: "+s2+" s2的hashcode:"+s2.hashCode()+" s2中stu1的hashcode:"+s2.getStu().hashCode());//System.out.println(s1.getStu().getAge()==s2.getStu().getAge());
  }
}

public void constructorCopy() {
 
  Student student = new Student ("小李",21,"男");
  School school = new School ("xx大学",100, student);
 
  // 调用构造函数时进行深拷贝
  School copySchool = new School (school.getSchoolName(),school.getStuNums(), new Student(student.getName(), student.getAge(),student.getSex()));
 
  // 修改源对象的值
  copySchool .getStudent().setSex("女");
 
  // 检查两个对象的值不同
  System.out.println(school.hashCode()==school2.hasCode())
 
}

public class School implements Cloneable{
  private String schoolName;
  private int stuNums;
  private Student stu;
  public String getSchoolName() {
    return schoolName;
  }
  public void setSchoolName(String schoolName) {
    this.schoolName = schoolName;
  }
  public int getStuNums() {
    return stuNums;
  }
  public void setStuNums(int stuNums) {
    this.stuNums = stuNums;
  }
  public Student getStu() {
    return stu;
  }
  public void setStu(Student stu) {
    this.stu = stu;
  }
  @Override
  protected School clone() throws CloneNotSupportedException {
    School school = (School) super.clone();
    school.stu = (Student) stu.clone();
    return school;
  }
  @Override
  public String toString() {
    return "School [schoolName=" + schoolName + ", stuNums=" + stuNums + ", stu=" + stu + "]";
  }
}

public class Student implements Cloneable{
  private String name;
  private int age;
  private String sex;
  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;
  }
  public String getSex() {
    return sex;
  }
  public void setSex(String sex) {
    this.sex = sex;
  }
  @Override
  public String toString() {
    return "Student [name=" + name + ", age=" + age + ", sex=" + sex + "]";
  }
  @Override
  protected Student clone() throws CloneNotSupportedException {
    return (Student)super.clone();
  }
}

import java.io.Serializable;
public class User implements Serializable {

  private String name;
  private Address2 address;

  public User(String name, Address2 address) {
    this.name = name;
    this.address = address;
  }

  public String getName() {
    return name;
  }

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

  public Address2 getAddress() {
    return address;
  }

  public void setAddress(Address2 address) {
    this.address = address;
  }
  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();
  }
}

import java.io.Serializable;
public class Address2 implements Serializable {
  private String city;
  private String country;

  public Address2(String city, String country) {
    this.city = city;
    this.country = country;
  }

  public String getCity() {
    return city;
  }

  public void setCity(String city) {
    this.city = city;
  }

  public String getCountry() {
    return country;
  }

  public void setCountry(String country) {
    this.country = country;
  }

  @Override
  public String toString() {
    return "Address2{" +
        "city='" + city + '\'' +
        ", country='" + country + '\'' +
        '}';
  }
}

public static void main(String[] args) throws Exception {
    Address2 address = new Address2("大同", "中国");
    User user = new User("yznl", address);
    User user2 = (User) user.deepClone();
    System.out.println(user.toString());
    System.out.println(user2.toString());

  }