Java--設計模式之原型模式

原型模式，用原型實例指定創建對象的種類，並且通過拷貝這些原型創建新的對象。通俗的說法就是從一個對象再創建另外一個可定製的對象，而且不需要知道任何創建的細節。

先看一個“錢復制”的例子

1、簡歷類

public class Resume implements Cloneable{
	private String name;
	private String sex;
	private String age;
	private String timeArea;
	private String company;
	public Resume(String name){
		this.name = name;
	}
	public void setPersonInfo(String sex,String age){
		this.sex = sex;
		this.age = age;
	}
	public void setWorkExperience(String timeArea,String company){
		this.timeArea = timeArea;
		this.company = company;
	}
	public void display(){
		System.out.println(name+":"+sex+":"+age);
		System.out.println("工作經歷"+timeArea+":"+company);
	}
	@Override
	protected Object clone(){
		Object o = null;
		try {
			o = super.clone();
		} catch (CloneNotSupportedException e) {
			e.printStackTrace();
		}
		return o;
	}
}

2、測試

public class Test {
	public static void main(String[] args) {
		Resume a = new Resume("大鳥");
		a.setPersonInfo("man", "22");
		a.setWorkExperience("2011-12-22", "XX公司");
		Resume b = (Resume)a.clone();
		b.setWorkExperience("2012-11-22", "YY公司");
		Resume c = (Resume)a.clone();
		c.setPersonInfo("man", "24");
		a.display();
		b.display();
		c.display();
	}
}

上面的例子是“淺複製”，讓我們把工作經驗用一個單獨的類來表示，看看結果如何，更改簡歷類

3、更改後的簡歷類

public class Resume implements Cloneable{
	private String name;
	private String sex;
	private String age;
	private WorkExperience work;
	public Resume(String name){
		this.name = name;
		work = new WorkExperience();
	}
	public void setPersonInfo(String sex,String age){
		this.sex = sex;
		this.age = age;
	}
	public void setWorkExperience(String workData,String company){
		work.setWorkData(workData);
		work.setCompany(company);
	}
	public void display(){
		System.out.println(name+":"+sex+":"+age);
		System.out.println("工作經歷"+work.getWorkData()+":"+work.getCompany());
	}
	@Override
	protected Object clone(){
		Object o = null;
		try {
			o = super.clone();
		} catch (CloneNotSupportedException e) {
			e.printStackTrace();
		}
		return o;
	}
}

淺複製，被複制對象的所有變量都含有與原來的對象相同的值，而所有的對其他對象的引用都仍然指向原來的對象。還有一種複製是深複製，深複製把引用對象的變量指向複製過的新對象，而不是原有的被引用的對象。下面我們來看看如何實現簡歷的深複製。

4、更改後的工作經驗類

public class WorkExperience implements Cloneable{
	private String workData;
	private String company;
	public String getWorkData() {
		return workData;
	}
	public void setWorkData(String workData) {
		this.workData = workData;
	}
	public String getCompany() {
		return company;
	}
	public void setCompany(String company) {
		this.company = company;
	}
	@Override
	protected Object clone(){
		Object o = null;
		try {
			o = super.clone();
		} catch (CloneNotSupportedException e) {
			e.printStackTrace();
		}
		return o;
	}
}

5、更改後的簡歷類

public class Resume implements Cloneable{
	private String name;
	private String sex;
	private String age;
	private WorkExperience work;
	public Resume(String name){
		this.name = name;
		work = new WorkExperience();
	}
	private Resume(WorkExperience work){
		this.work = (WorkExperience)work.clone();
	}
	public void setPersonInfo(String sex,String age){
		this.sex = sex;
		this.age = age;
	}
	public void setWorkExperience(String workData,String company){
		work.setWorkData(workData);
		work.setCompany(company);
	}
	public void display(){
		System.out.println(name+":"+sex+":"+age);
		System.out.println("工作經歷"+work.getWorkData()+":"+work.getCompany());
	}
	@Override
	protected Object clone(){
		Resume obj = new Resume(this.work);
		obj.name = this.name;
		obj.age = this.age;
		obj.sex = this.sex;
		return obj;
	}
}