java设计模式——Prototype(原型模式)

原型模式可以通过一个对象实例确定创建对象的种类，并且通过拷贝创建新的实例。总得来说，原型模式实际上就是从一个对象创建另一个新的对象，使新的对象有具有原对象的特征。

1.案例一
学生复制

package Prototype;

/**
* Created by Jim on 2016/10/1.
*/
public class Student implements Cloneable{
private String stuName;
private String stuSex;
private int stuAge;
private String stuMajor;
private String stuCollege;
private String stuUniversity;

public Student(String stuName,String stuSex,int stuAge,String stuMajor,String stuCollege,String stuUniversity) { // 构造函数
this.stuName = stuName;
this.stuSex = stuSex;
this.stuAge = stuAge;
this.stuMajor = stuMajor;
this.stuCollege = stuCollege;
this.stuUniversity = stuUniversity;
}

public void setStuName(String stuName) {
this.stuName = stuName;
}

public void setStuSex(String stuSex) {
this.stuSex = stuSex;
}

public void setStuAge(int stuAge) {
this.stuAge = stuAge;
}

public void setStuMajor(String stuMajor) {
this.stuMajor = stuMajor;
}

public void setStuCollege(String stuCollege) {
this.stuCollege = stuCollege;
}

public void setStuUniversity(String stuUniversity) {
this.stuUniversity = stuUniversity;
}

public String getStuName() {
return this.stuName;
}

public String getStuSex() {
return this.stuSex;
}

public int getStuAge() {
return this.stuAge;
}

public String getStuMajor() {
return this.stuMajor;
}

public String getStuCollege() {
return this.stuCollege;
}

public String getStuUniversity() {
return this.stuUniversity;
}

public Student clone() { // 实现克隆
Student cpStudent = null;
try{
cpStudent=(Student)super.clone();
}catch (CloneNotSupportedException e) {

}
return cpStudent;
}
}

// 继续写类
class MainClass
{
public static void main(String args[]) {
Student stu1,stu2,stu3;
stu1 = new Student("张无忌","男",24,"软件","信息工程学院","南京财经大学");

// 使用原型
stu2 = stu1.clone();
stu2.setStuName("杨过");

stu3 = stu1.clone();
stu3.setStuName("小龙女");
stu3.setStuSex("女");

System.out.print("姓名:" + stu1.getStuName());
System.out.print(",性别:" + stu1.getStuSex());
System.out.print(",年龄:" + stu1.getStuAge());
System.out.print(",专业:" + stu1.getStuMajor());
System.out.print(",学院:" + stu1.getStuCollege());
System.out.print(",大学:" + stu1.getStuUniversity());
System.out.println();

System.out.print("姓名:" + stu2.getStuName());
System.out.print(",性别:" + stu2.getStuSex());
System.out.print(",年龄:" + stu2.getStuAge());
System.out.print(",专业:" + stu2.getStuMajor());
System.out.print(",学院:" + stu2.getStuCollege());
System.out.print(",大学:" + stu2.getStuUniversity());
System.out.println();

System.out.print("姓名:" + stu3.getStuName());
System.out.print(",性别:" + stu3.getStuSex());
System.out.print(",年龄:" + stu3.getStuAge());
System.out.print(",专业:" + stu3.getStuMajor());
System.out.print(",学院:" + stu3.getStuCollege());
System.out.print(",大学:" + stu3.getStuUniversity());
System.out.println();
}
}

执行结果:
姓名:张无忌,性别:男,年龄:24,专业:软件,学院:信息工程学院,大学:南京财经大学
姓名:杨过,性别:男,年龄:24,专业:软件,学院:信息工程学院,大学:南京财经大学
姓名:小龙女,性别:女,年龄:24,专业:软件,学院:信息工程学院,大学:南京财经大学

2.邮件与附件
附件类

package Prototype;

/**
* Created by Jim on 2016/10/1.
*/
public class Attachment {
public void download() {
System.out.println("下载附件");
}
}

邮件类

package Prototype;

/**
* Created by e550 on 2016/10/1.
*/
public class Email implements Cloneable{
private Attachment attachment = null;

public Email() {
this.attachment = new Attachment();
}

public Object clone() {
Email clone = null;
try{
clone=(Email)super.clone();
}catch (CloneNotSupportedException e){
System.out.println("Clone failure!");
}
return clone;
}

public Attachment getAttachment() {
return this.attachment;
}

public void display() {
System.out.println("查看邮件");
}
}

客户端

package Prototype;

/**
* Created by e550 on 2016/10/1.
*/
public class Client {
public static void main(String a[]) {
Email email,cpEmail;
email = new Email();
cpEmail = (Email)email.clone();

System.out.println("email==cpEmail?");
System.out.println(email==cpEmail);

System.out.println("email.getAttachment==cpEmail.getAttachment?");
System.out.println(email.getAttachment()==cpEmail.getAttachment());
}
}

执行结果

email==cpEmail?
false
email.getAttachment==cpEmail.getAttachment?
true

说明:
这种克隆，没有把引用的变量克隆出来。

3.改造邮件类，通过流实现深克隆
附件类

package Prototype.deepClone;
import java.io.*;

/**
* Created by e550 on 2016/10/1.
*/
public class Attachment implements Serializable{
public void download() {
System.out.println("下载附件");
}
}

邮件类

package Prototype.deepClone;
import java.io.*;
/**
* Created by e550 on 2016/10/1.
*/
public class Email implements Serializable{
private Attachment attachment = null;
public Email() {
this.attachment = new Attachment();
}

public Object deepClone() throws IOException , ClassNotFoundException, OptionalDataException
{
// 将对象写入流中
ByteArrayOutputStream bao = new ByteArrayOutputStream();
ObjectOutputStream oss = new ObjectOutputStream(bao);
oss.writeObject(this);

//将对象从流中取出
ByteArrayInputStream bis = new ByteArrayInputStream(bao.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bis);
return(ois.readObject());
}

public Attachment getAttachment() {
return this.attachment;
}

public void display() {
System.out.println("查看邮件");
}

}

客户端类

package Prototype.deepClone;

public class Client
{
public static void main(String a[])
{
Email email,copyEmail=null;

email=new Email();

try{
copyEmail=(Email)email.deepClone();
}
catch(Exception e)
{
e.printStackTrace();
}

System.out.println("email==copyEmail?");
System.out.println(email==copyEmail);

System.out.println("email.getAttachment==copyEmail.getAttachment?");
System.out.println(email.getAttachment()==copyEmail.getAttachment());
}
}

执行结果

email==copyEmail?
false
email.getAttachment==copyEmail.getAttachment?
false