设计模式原型模式 Prototype

旧城等待， 2022-07-26 05:25 168阅读 0赞

原型模式prototype pattern，用原型实例指定创建对象的种类，并且通过拷贝这些原型创建新的对象。

原型模式的结构图：

![Center][]

原型模式其实就是从一个对象再创建另外一个可定制的对象，而且不需要知道任何创建的细节。它采取复制原型对象的方法来创建对象的实例。

原型模式的代码：

abstract class Prototype\{

private String id;

public Prototype(String id)\{

this.id =id;

public String id

get \{return id;\}

public abstract Prototype Clone();//抽象类关键就是这样一个Clone方法

具体的原型类：

class ConcretePrototype :Prototype\{

public ConcretePrototype (String id) :base(id)\{

public override Prototype Clone()\{

return super.Clone();

客户端的代码：

static void main(String\[\] args)\{

ConcretePrototype cp1 = new ConcretePrototype("1");

ConcretePrototype cp2 = (ConcretePrototype)cp1.Clone();

Java语言是直接支持原型模式的，java.lang.Object是一切接口和类的父类，Object中提供了一个clone()方法来支持原型模式。如果一个对象想具有被复制的能力，必须实现Cloneable接口。复制份浅复制和深复制，浅复制是对基本数据类型和String类型而言，深复制是对其他引用类型而言，对于深复制，每个引用都要实现Cloneable接口。

下面以这样一个需求为例，面试都要做简历，现在要求有一个简历类，必须有姓名，可以设置性别，年龄，工作经历，最终需要两份这样的简历。

首先是一个浅复制的例子，这里有一个设置工作经历的方法：

package prototype.pattern;  
public class ResumeShallow implements Cloneable \{  
private String mName=null;  
private String mSex=null;  
private String mAge=null;  
private String mWork\_time =null;  
private String mWork\_compony=null;  
  
public ResumeShallow(String name)\{  
this.mName = name;  
\}  
  
public void setPersonalInfo(String sex,String age)\{  
this.mSex = sex;  
this.mAge = age;  
\}  
  
public void setWorkExperience(String work\_time,String compony)\{  
this.mWork\_time = work\_time;  
this.mWork\_compony = compony;  
\}  
  
public void display()\{  
System.out.println("Name :"+mName+",Sex:"+mSex+",Age:"+mAge);  
System.out.println("Work experience,work-time:"+mWork\_time+",work-compony:"+mWork\_compony);  
\}  
  
@Override  
protected ResumeShallow clone() throws CloneNotSupportedException \{  
return (ResumeShallow)super.clone();  
\}  
  
//客户端代码  
public static void main(String\[\] args) throws CloneNotSupportedException\{  
ResumeShallow rA = new ResumeShallow("大牛");  
rA.setPersonalInfo("男", "26");  
rA.setWorkExperience("2015-2016", "QQ 企业");  
  
ResumeShallow rB = (ResumeShallow)rA.clone();  
rB.setPersonalInfo("女", "25");  
rB.setWorkExperience("2012-2014", "WW 企业");  
  
rA.display();  
rB.display();  
\}  
\}

输出结果：

Name :大牛,Sex:男,Age:26  
Work experience,work-time:2015-2016,work-compony:QQ 企业  
Name :大牛,Sex:女,Age:25  
Work experience,work-time:2012-2014,work-compony:WW 企业

然后是深复制的代码，现实中应该通常会再有一个工作经历的类：

先定义一个Workexperience 类，

package prototype.pattern;  
public class WorkExperience implements Cloneable\{  
private String mWork\_time =null;  
private String mWork\_compony=null;  
  
public String getmWork\_time() \{  
return mWork\_time;  
\}  
public void setmWork\_time(String mWork\_time) \{  
this.mWork\_time = mWork\_time;  
\}  
public String getmWork\_compony() \{  
return mWork\_compony;  
\}  
public void setmWork\_compony(String mWork\_compony) \{  
this.mWork\_compony = mWork\_compony;  
\}  
  
@Override  
protected WorkExperience clone() throws CloneNotSupportedException \{  
return (WorkExperience)super.clone();  
\}  
\}

public class ResumeDeep implements Cloneable \{  
private String mName=null;  
private String mSex=null;  
private String mAge=null;  
private WorkExperience mWorkExperience =null;  
  
public ResumeDeep(String name)\{  
this.mName = name;  
mWorkExperience = new WorkExperience();  
\}  
  
public ResumeDeep(WorkExperience workexperience) throws CloneNotSupportedException\{

//让工作经历完成clone，复制工作经历的数据  
mWorkExperience = (WorkExperience)workexperience.clone();  
\}  
  
  
public void setPersonalInfo(String sex,String age)\{  
this.mSex = sex;  
this.mAge = age;  
\}  
  
public void setWorkExperience(String work\_time,String compony)\{  
mWorkExperience.setmWork\_time(work\_time);  
mWorkExperience.setmWork\_compony(compony);  
\}  
  
public void display()\{  
System.out.println("Name :"+mName+",Sex:"+mSex+",Age:"+mAge);  
System.out.println("Work experience,work-time:"+mWorkExperience.getmWork\_time()  
\+",work-compony:"+mWorkExperience.getmWork\_compony());  
\}  
  
@Override  
protected ResumeDeep clone() throws CloneNotSupportedException \{  
ResumeDeep mResumeDeep = new ResumeDeep(mWorkExperience);  
mResumeDeep.mName = this.mName;  
mResumeDeep.mSex = this.mSex;  
mResumeDeep.mAge = this.mAge;  
  
return mResumeDeep;  
\}  
  
  
public static void main(String\[\] args) throws CloneNotSupportedException\{  
ResumeDeep rA = new ResumeDeep("大牛");  
rA.setPersonalInfo("男", "26");  
rA.setWorkExperience("2015-2016", "QQ 企业");  
  
ResumeDeep rB = (ResumeDeep)rA.clone();  
rB.setPersonalInfo("女", "25");  
rB.setWorkExperience("2012-2014", "WW 企业");  
  
rA.display();  
rB.display();  
\}  
\}

输出结果：

Name :大牛,Sex:男,Age:26  
Work experience,work-time:2015-2016,work-compony:QQ 企业  
Name :大牛,Sex:女,Age:25  
Work experience,work-time:2012-2014,work-compony:WW 企业

[Center]: /images/20220724/279b03b27d5c4676bf1c0462f21d0d8c.png