java-深克隆和浅克隆

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文章参考 https://www.cnblogs.com/acode/p/6306887.html

一、前提

    1、使用clone()方法的类,必须实现Cloneable接口,

          否则调用clone()方法时候,会抛出  CloneNotSupportedException

     2、clone()为protected修饰符方法,所以如果想使用clone()方法,必须在子类中实现

二、实战

   类关系(

                Student:两个基础类型属性

                                一个引用类型属性)

    1、创建一个Student类

@Data
public class Student implements Cloneable{

private String name;

private int age;

private Mother mother ;

@Override
protected Object clone() throws CloneNotSupportedException {
Student student = (Student) super.clone();
try {
Mother mother1 = (Mother)mother.clone();
student.setMother(mother1);
} catch (Exception e) {
e.printStackTrace();
}
return student;
}
}

   2、创建一个Mother类

@Data
public class Mother implements Cloneable {

    private String name;

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

3、创建一个测试类

public class Test {

public static void main(String[] args) throws Exception {
//============初始化================
Mother mother = new Mother();
mother.setName("小王mama");
mother.setAge(40);
Student student = new Student();
student.setAge(1);
student.setName("小王");
student.setMother(mother);
//============克隆================
Student student2 = (Student)student.clone();
student2.setName("小李");
student2.setAge(2);
student2.getMother().setAge(45);
student2.getMother().setName("小李mama");
//============输出================
System.out.println(student);
System.out.println(student2);
}
}  

三、结果

Student(name=小王, age=1, mother=Mother(name=小王mama, age=40))
Student(name=小李, age=2, mother=Mother(name=小李mama, age=45))

四、分析

1、结果实现类深度克隆

2、如果在Student类的clone()方法中没有,进行Mother类的操作,则Mother属性只会进行引用操作

      修改Student类中的clone()方法

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

      结果

Student(name=小王, age=1, mother=Mother(name=小李mama, age=45))
Student(name=小李, age=2, mother=Mother(name=小李mama, age=45))

3、歪门邪术(实现序列化接口,实现clone)  对象串行化,但是串行化却很耗时,在一些框架中,我们便可以感受到,它们往往将对象进行串行化后进行传递,耗时较多。

@Data
public class Student  implements Serializable{

    private static final long serialVersionUID = 1L;


    private String name;

    private int age;


    private Mother mother ;

    public Object deepClone() throws IOException, 
            ClassNotFoundException {
        // 将对象写到流里
        ByteArrayOutputStream bo = new ByteArrayOutputStream();
        ObjectOutputStream oo = new ObjectOutputStream(bo);
        oo.writeObject(this);
        // 从流里读出来
        ByteArrayInputStream bi = new ByteArrayInputStream(bo.toByteArray());
        ObjectInputStream oi = new ObjectInputStream(bi);
        return (oi.readObject());
    }
}
@Data
public class Mother implements Serializable {

    private static final long serialVersionUID = 1L;

    private String name;

    private int age;
    
}

结果:深度克隆成功

Student(name=小王, age=1, mother=Mother(name=小王mama, age=40))
Student(name=小李, age=2, mother=Mother(name=小李mama, age=45))

 

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