那應(yīng)該如何實(shí)現(xiàn)深層次的克隆，即修改s2的教授不會(huì)影響s1的教授？代碼改進(jìn)如下。
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改進(jìn)使學(xué)生1的Professor不改變（深層次的克隆）
class Professor implements Cloneable
{
??? String name;
??? int age;
??? Professor(String name,int age)
??? {
??????? this.name=name;
??????? this.age=age;
??? }
??? public Object clone()
??? {
??????? Object o=null;
??????? try
??????? {
??????????? o=super.clone();
??????? }
??????? catch(CloneNotSupportedException e)
??????? {
??????????? System.out.println(e.toString());
??????? }
??????? return o;
??? }
}
class Student implements Cloneable
{
??? String name;
??? int age;
??? Professor p;
??? Student(String name,int age,Professor p)
??? {
??????? this.name=name;
??????? this.age=age;
??????? this.p=p;
??? }
??? public Object clone()
??? {
??????? Student o=null;
??????? try
??????? {
??????????? o=(Student)super.clone();
??????? }
??????? catch(CloneNotSupportedException e)
??????? {
??????????? System.out.println(e.toString());
??????? }
??????? o.p=(Professor)p.clone();
??????? return o;
??? }
???
public static void main(String[] args)
??? {
????? Professor p=new Professor("wangwu",50);
????? Student s1=new Student("zhangsan",18,p);
????? Student s2=(Student)s1.clone();
????? s2.p.name="lisi";
??? ?s2.p.age=30;
System.out.println("name="+s1.p.name+","+"age="+s1.p.age);//學(xué)生1的教授不改變。
}
}
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3．利用串行化來(lái)做深復(fù)制
把對(duì)象寫(xiě)到流里的過(guò)程是串行化（Serilization）過(guò)程，但是在Java程式師圈子里又很形象地稱(chēng)為“冷凍”或“腌咸菜（picking）”過(guò)程；而把對(duì)象從流中讀出來(lái)的并行化（Deserialization）過(guò)程則叫做“解凍”或“回鮮(depicking)”過(guò)程。應(yīng)當(dāng)指出的是，寫(xiě)在流里的是對(duì)象的一個(gè)拷貝，而原對(duì)象仍然存在于JVM里面，因此“腌成咸菜”的只是對(duì)象的一個(gè)拷貝，Java咸菜還能夠回鮮。
在Java語(yǔ)言里深復(fù)制一個(gè)對(duì)象，常常能夠先使對(duì)象實(shí)現(xiàn)Serializable接口，然后把對(duì)象（實(shí)際上只是對(duì)象的一個(gè)拷貝）寫(xiě)到一個(gè)流里（腌成咸菜），再?gòu)牧骼镒x出來(lái)（把咸菜回鮮），便能夠重建對(duì)象。
如下為深復(fù)制源代碼。
public Object deepClone()
{
?//將對(duì)象寫(xiě)到流里
?ByteArrayOutoutStream bo=new ByteArrayOutputStream();
?ObjectOutputStream oo=new ObjectOutputStream(bo);
?oo.writeObject(this);
?//從流里讀出來(lái)
?ByteArrayInputStream bi=new ByteArrayInputStream(bo.toByteArray());
?ObjectInputStream oi=new ObjectInputStream(bi);
?return(oi.readObject());
}
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這樣做的前提是對(duì)象連同對(duì)象內(nèi)部任何引用到的對(duì)象都是可串行化的，否則，就需要仔細(xì)考察那些不可串行化的對(duì)象可否設(shè)成transient，從而將之排除在復(fù)制過(guò)程之外。上例代碼改進(jìn)如下。
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class Professor implements Serializable
{
??? String name;
??? int age;
??? Professor(String name,int age)
??? {
??????? this.name=name;
??????? this.age=age;
??? }
}
class Student implements Serializable
{
??? String name;//常量對(duì)象。
??? int age;
??? Professor p;//學(xué)生1和學(xué)生2的引用值都是相同的。
??? Student(String name,int age,Professor p)
??? {
??????? this.name=name;
??????? this.age=age;
??????? this.p=p;
??? }
??? public Object deepClone() throws IOException,
OptionalDataException,ClassNotFoundException
{
?//將對(duì)象寫(xiě)到流里
?ByteArrayOutoutStream bo=new ByteArrayOutputStream();
?ObjectOutputStream oo=new ObjectOutputStream(bo);
?oo.writeObject(this);
?//從流里讀出來(lái)
?ByteArrayInputStream bi=new ByteArrayInputStream(bo.toByteArray());
?ObjectInputStream oi=new ObjectInputStream(bi);
?return(oi.readObject());
}
public static void main(String[] args)
??? {
????? Professor p=new Professor("wangwu",50);
????? Student s1=new Student("zhangsan",18,p);
????? Student s2=(Student)s1.deepClone();
????? s2.p.name="lisi";
??? ?s2.p.age=30;
System.out.println("name="+s1.p.name+","+"age="+s1.p.age); //學(xué)生1的教授不改變。
}
}
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