抖音代运营公司,深圳网站优化页面,在哪里做马可波罗网站,品牌网站建设保障大蝌蚪什么是java中的浅克隆和深克隆? 浅克隆:克隆对象中的变量与之前对象的值相同,并且对象中的引用类型变量仍然指向原来对象引用类型变量的地址. 深克隆:克隆对象中的变量与之前对象的值相同#xff0c;并且对象中的引用类型变量指向了新的对象的引用变量的地址. 要想实现克隆并且对象中的引用类型变量指向了新的对象的引用变量的地址. 要想实现克隆只需定义的类声明下cloneable这个标记性接口,并且衍生重写Object类中就有的clone()方法即可. 为什么类要首先声明cloneable标记接口然后重写clone()方法因为不声明cloneable调用clone()方法会抛出CloneNotSupportedException异常,源码如下: protected Object clone() throws CloneNotSupportedException { if (!(this instanceof Cloneable)) { throw new CloneNotSupportedException(Class getClass().getName() doesnt implement Cloneable); } return internalClone(); } /* * Native helper method for cloning. */ private native Object internalClone(); 在上一节中讲了java中Serializable与Parcelable的使用序列化与反序列化的问题。事实上利用对象输出流对对象进行序列化,利用对象的输入流对对象进行反序列化也可以实现克隆,如果对象中依赖的其他对象的引用也实现了序列化(即引用类实现了serializable标记接口)就实现了深度克隆,否则实现了浅克隆. 实现了Serializable接口的Company public class Company implements Serializable {//Serializable接口是空的,没有声明的方法及常量 private static final long serialVersionUID 1L; //序列化标识 private String name; private String address; public String getName() { return name; } public void setName(String name) { this.name name; } public String getAddress() { return address; } public void setAddress(String address) { this.address address; } public Company(String name, String address) { this.name name; this.address address; } Override public String toString() { return company name is:name,address is:address; } } 获得实现了Serializable接口的克隆实例调用方法。 private T getCopyObj(T t) { ByteArrayOutputStream byteArrayOutputStream null; ObjectOutputStream objectOutputStream null; ByteArrayInputStream byteArrayInputStream null; ObjectInputStream objectInputStream null; try { byteArrayOutputStream new ByteArrayOutputStream(); objectOutputStream new ObjectOutputStream(byteArrayOutputStream); objectOutputStream.writeObject(t);//序列化对象 objectOutputStream.flush(); byteArrayInputStream new ByteArrayInputStream(byteArrayOutputStream.toByteArray()); objectInputStream new ObjectInputStream(byteArrayInputStream); T t1 (T) objectInputStream.readObject(); return t1; } catch (Exception e) { e.printStackTrace(); } finally { if (byteArrayOutputStream ! null) { try { byteArrayOutputStream.close(); byteArrayOutputStream null; } catch (IOException e) { e.printStackTrace(); } } if (objectOutputStream ! null) { try { objectOutputStream.close(); objectOutputStream null; } catch (IOException e) { e.printStackTrace(); } } if (byteArrayInputStream ! null) { try { byteArrayInputStream.close(); byteArrayInputStream null; } catch (IOException e) { e.printStackTrace(); } } if (objectInputStream ! null) { try { objectInputStream.close(); objectInputStream null; } catch (IOException e) { e.printStackTrace(); } } } return null; } } 测试通过的testCase说明通过Serializable的反序列化创建的是一个新的对象,不再是之前的对象了。 Test public void test() throws CloneNotSupportedException { Company companynew Company(百度,上地十街); Company copyCompanygetCopyObj(company); copyCompany.setName(腾讯); Assert.assertEquals(false,companycopyCompany); Assert.assertEquals(true,company.getName().equals(百度)); Assert.assertEquals(true,copyCompany.getName().equals(腾讯)); } 实现了Clonable克隆的例子 public class People implements Cloneable { private String name; private int age; public People(String name, int age) { this.name name; this.age age; } Override protected Object clone() throws CloneNotSupportedException { return super.clone(); } 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; } } 验证通过的case,表明了克隆出来的对象与原来的对象地址不一样,是一个新的对象,所以克隆对象中的name和age是新的. Test public void test() throws CloneNotSupportedException { People people new People(storm, 30); People clonePeople (People) people.clone(); clonePeople.setName(stormClone); clonePeople.setAge(29); Assert.assertFalse(people clonePeople); System.out.println(people name people.getName());//people namestorm System.out.println(people age people.getAge());//people age30 System.out.println(clonePeople name clonePeople.getName());//clonePeople namestormClone System.out.println(clonePeople age clonePeople.getAge());//clonePeople age29 } 使用cloneable实现浅克隆 public class Animal { private String animalName; public Animal(String animalName) { this.animalName animalName; } public String getAnimalName() { return animalName; } public void setAnimalName(String animalName) { this.animalName animalName; } } public class People implements Cloneable { private String name; private int age; private Animal animal;//克隆对象中的引用型变量 public People(String name, int age,Animal animal) { this.name name; this.age age; this.animalanimal; } Override protected Object clone() throws CloneNotSupportedException { return super.clone(); } 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 Animal getAnimal() { return animal; } public void setAnimal(Animal animal) { this.animal animal; } } 验证通过的case表明了克隆对象的引用型变量animal并未发生改变,也即使内存中的地址并未发生改变,所以对其name的更改会影响原对象与克隆对象的值. Test public void test() throws CloneNotSupportedException { Animal animalnew Animal(cat); People people new People(storm, 30,animal); People clonePeople (People) people.clone(); animal.setAnimalName(dog); Assert.assertFalse(people clonePeople); Assert.assertTrue(people.getAnimal()clonePeople.getAnimal()); Assert.assertTrue(people.getAnimal().getAnimalName().equals(dog)); Assert.assertTrue(clonePeople.getAnimal().getAnimalName().equals(dog)); } 使用cloneable实现深克隆(实现很简单只需要引用类型变量实现cloneable接口即可)相比浅克隆,只需做如下修改. public class Animal implements Cloneable{ private String animalName; public Animal(String animalName) { this.animalName animalName; } public String getAnimalName() { return animalName; } public void setAnimalName(String animalName) { this.animalName animalName; } Override protected Object clone() throws CloneNotSupportedException { return super.clone(); } } 验证通过的case表明了克隆对象的引用型变量animal发生改变,也即内存中的地址发生改变,所以对其name的更改不会影响克隆对象的值.同时说明了进行深克隆会把所有的引用类型都实现cloneable接口,如果克隆对象中的引用类型变量比较多的话,这牵涉的工作量就会比较大了,这时我们考虑使用上面实现Serializable实现克隆的方式,缺点是反复进行IO操作内存开销大. Test public void test() throws CloneNotSupportedException { Animal animalnew Animal(cat); People people new People(storm, 30,animal); People clonePeople (People) people.clone(); Animal cloneAnimal(Animal) animal.clone(); clonePeople.setAnimal(cloneAnimal); animal.setAnimalName(dog); Assert.assertFalse(people clonePeople); Assert.assertFalse(people.getAnimal()clonePeople.getAnimal()); Assert.assertTrue(people.getAnimal().getAnimalName().equals(dog)); Assert.assertTrue(clonePeople.getAnimal().getAnimalName().equals(cat)); }
