1.Java里的clone分为两种形式：
A:浅克隆： 浅克隆仅仅克隆所考虑的对象，而不复制它所引用的对象。
b:深克隆：深克隆不仅克隆所考虑的对象，还要克隆其引用所有对象。
Java中对象的克隆,为了获取对象的一份拷贝，我们可以利用Object类的clone()方法。必须要遵循下面三点
1、在派生类中实现Cloneable接口。
2、.在派生类中覆盖基类的clone()方法，并声明为public【Object类中的clone()方法为protected的】。
3、.在派生类的clone()方法中，调用super.clone()。
现在举例说明：
浅克隆：Java中的Object类里的clone是浅克隆。
一个教师类如下：
public
class
Teacher {
public
int
age;
public
String name;
public
int
getAge() {
return
age;
}
public
void
setAge(
int
age) {
this
.age
=
age;
}
public
String getName() {
return
name;
}
public
void
setName(String name) {
this
.name
=
name;
}
}
一个学生类如下（如果应用Object类中的clone实现克隆功能就要实现Cloneable接口）：
public
class
Student
implements
Cloneable{
public
String name;
public
int
age;
public
Teacher teacher;
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
Teacher getTeacher() {
return
teacher;
}
public
void
setTeacher(Teacher teacher) {
this
.teacher
=
teacher;
}
@Override
protected
Object clone()
throws
CloneNotSupportedException {
return
super
.clone();
}
测试浅克隆如下：
public
class
TestClone {
public
static
void
main(String[] args) {
Teacher teacher
=
new
Teacher();
teacher.setAge(
21
);
teacher.setName(
"
Teacher Zhang
"
);
Student student1
=
new
Student();
student1.setAge(
5
);
student1.setName(
"
Student zhangsan
"
);
student1.setTeacher(teacher);
//
复制出来一个对象student2
Student student2;
try
{
student2
=
(Student) student1.clone();
System.out.println(student2.getAge());
System.out.println(student2.getName());
System.out.println(
"
~~~~~~~~~~~~~~~~~~~~~~
"
);
System.out.println(student1.getTeacher().getAge());
System.out.println(student1.getTeacher().getName());
//
修改student2的引用对象
student2.getTeacher().setAge(
50
);
student2.getTeacher().setName(
"
Teacher Li
"
);
System.out.println(
"
~~~~~~~~~~~~~~~~~~~~~~
"
);
System.out.println(student1.getTeacher().getAge());
System.out.println(student1.getTeacher().getName());
}
catch
(CloneNotSupportedException e) {
//
TODO Auto-generated catch block
e.printStackTrace();
}
}
}
执行结果如下：
5
Student zhangsan
~~~~~~~~~~~~~~~~~~~~~~
21
Teacher Zhang
~~~~~~~~~~~~~~~~~~~~~~
50
Teacher Li
深克隆（一）：
教师类如下：（如果应用Object类中的clone实现克隆功能就要实现Cloneable接口）
public
class
Teacher
implements
Cloneable{
public
int
age;
public
String name;
public
int
getAge() {
return
age;
}
public
void
setAge(
int
age) {
this
.age
=
age;
}
public
String getName() {
return
name;
}
public
void
setName(String name) {
this
.name
=
name;
}
@Override
protected
Object clone()
throws
CloneNotSupportedException {
return
super
.clone();
}
}
学生类如下：（要实现深克隆就要把其引用的对象全部克隆）
public
class
Student
implements
Cloneable{
public
String name;
public
int
age;
public
Teacher teacher;
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
Teacher getTeacher() {
return
teacher;
}
public
void
setTeacher(Teacher teacher) {
this
.teacher
=
teacher;
}
@Override
protected
Object clone()
throws
CloneNotSupportedException {
Student student
=
(Student)
super
.clone();
student.setTeacher((Teacher)student.getTeacher().clone());
return
student
;
}
}
测式类同上：
测结果如下：
5
Student zhangsan
~~~~~~~~~~~~~~~~~~~~~~
21
Teacher Zhang
~~~~~~~~~~~~~~~~~~~~~~
21
Teacher Zhang
深克隆（二）：采用可序列化的形式实现深克隆。
教师类如下：（实现Serializable接口）
public
class
Teacher
implements
Serializable {
private
static
final
long
serialVersionUID
=
1L
;
public
int
age;
public
String name;
public
int
getAge() {
return
age;
}
public
void
setAge(
int
age) {
this
.age
=
age;
}
public
String getName() {
return
name;
}
public
void
setName(String name) {
this
.name
=
name;
}
}
学生类如下：（实现Serializable接口）
import
java.io.ByteArrayInputStream;
import
java.io.ByteArrayOutputStream;
import
java.io.IOException;
import
java.io.ObjectInputStream;
import
java.io.ObjectOutputStream;
import
java.io.Serializable;
public
class
Student
implements
Serializable {
//
serialVersionUID
//
如果你的对象序列化后存到硬盘上面后，可是后来你却更改了类的field(增加或减少或改名)，当你反序列化时，就会出现Exception的，这样就会造成不兼容性的问题。
//
但当serialVersionUID相同时，它就会将不一样的field以type的缺省值赋值(如int型的是0,String型的是null等)，这个可以避开不兼容性的问题。所以最好给serialVersionUID赋值
private
static
final
long
serialVersionUID
=
1L
;
public
String name;
public
int
age;
public
Teacher teacher;
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
Teacher getTeacher() {
return
teacher;
}
public
void
setTeacher(Teacher teacher) {
this
.teacher
=
teacher;
}
public
Object deepCopy()
throws
IOException, ClassNotFoundException {
//
将该对象序列化成流,因为写在流里的是对象的一个拷贝，而原对象仍然存在于JVM里面。所以利用这个特性可以实现对象的深拷贝
ByteArrayOutputStream bos
=
new
ByteArrayOutputStream();
ObjectOutputStream oos
=
new
ObjectOutputStream(bos);
oos.writeObject(
this
);
//
将流序列化成对象
ByteArrayInputStream bis
=
new
ByteArrayInputStream(bos.toByteArray());
ObjectInputStream ois
=
new
ObjectInputStream(bis);
return
ois.readObject();
}
}
测试类：是把上面的测试类中的student1.clone()改成student1.deepCopy();执行。
测试结果如下：
12
Student zhangsan
~~~~~~~~~~~~~~~~~~~~~~
21
Teacher Zhang
~~~~~~~~~~~~~~~~~~~~~~
21
Teacher Zhang
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