浅克隆
对于浅克隆，对象是克隆了，但是里面的类确实用的同一个，示例如下：
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public class Pig implements Cloneable {
private String name;
private Date birthday;
public Pig(String name, Date birthday) {
this.name = name;
this.birthday = birthday;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "Pig{" +
"name='" + name + '\'' +
", birthday=" + birthday +
'}'+super.toString();
}
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
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public class Test {
public static void main(String[] args) throws CloneNotSupportedException {
Date birthday=new Date(0);
Pig pig1=new Pig("佩奇",birthday);
Pig pig2= (Pig) pig1.clone();
System.out.println(pig1);
System.out.println(pig2);
pig1.getBirthday().setTime(4839480394034L);
System.out.println(pig1);
System.out.println(pig2);
}
}
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输出
深克隆
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| @Override
protected Object clone() throws CloneNotSupportedException {
Pig pig= (Pig) super.clone();
pig.birthday= (Date) pig.birthday.clone();
return pig;
}
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对克隆的反射攻击破坏单例模式
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| HungrySingleton hungrySingleton=HungrySingleton.getInstance();
Method method = hungrySingleton.getClass().getDeclaredMethod("clone");
method.setAccessible(true);
HungrySingleton hungrySingleton1 = (HungrySingleton) method.invoke(hungrySingleton);
System.out.println(hungrySingleton);
System.out.println(hungrySingleton1);
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解决方案
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| @Override
protected Object clone() throws CloneNotSupportedException {
return getInstance();
}
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或者不实现Cloneable