设计模式(21)：备忘录模式-代码实现

• 源发器类(Originator)

/**
 * 源发器对象
 */
public class Emp {
	private String name;
	private int age;
	private double salary;
	//进行备忘操作，并返回备忘对象
	public EmpMemento memento(){
		return new EmpMemento(this);	
	}
	//进行数据恢复，恢复成指定备忘录对象的值
	public void recovery(EmpMemento memneto){
		this.name=memneto.getName();
		this.age=memneto.getAge();
		this.salary=memneto.getSalary();
	}
	public Emp(String name, int age, double salary) {
		this.name = name;
		this.age = age;
		this.salary = salary;
	}
	public String getName() {
		return name;
	}
	public int getAge() {
		return age;
	}
	public double getSalary() {
		return salary;
	}
	public void setName(String name) {
		this.name = name;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}
}

• 备忘录类(Memento)

/**
 * 备忘录对象
 */
public class EmpMemento {
	private String name;
	private int age;
	private double salary;
	public EmpMemento(Emp e) {
		this.name = e.getName();
		this.age = e.getAge();
		this.salary =e.getSalary();
	}
	public String getName() {
		return name;
	}
	public int getAge() {
		return age;
	}
	public double getSalary() {
		return salary;
	}
	public void setName(String name) {
		this.name = name;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}
}

• 负责人类(CareTaker)

/**
 * 负责人对象
 * 负责管理备忘录对象
 */
public class CareTaker {
	private Stack<EmpMemento> stack=new Stack(); //很多备忘录对象
	public EmpMemento getMemento() {
		return stack.pop();
	}
	public void setMemento(EmpMemento memento) {
		stack.add(memento);
	}	
}

• 客户端调用

public static void main(String[] args) {
	CareTaker t=new CareTaker();
	Emp e=new Emp("张三",18,1800);
	System.out.println("没更改:"+e.getName()+"\t"+e.getAge()+"\t"+e.getSalary());
	t.setMemento(e.memento());//备忘
	e.setName("李四");
	e.setAge(28);
	e.setSalary(2800);
	System.out.println("第一次修改后:"+e.getName()+"\t"+e.getAge()+"\t"+e.getSalary());
	t.setMemento(e.memento());//备忘
	e.setName("王五");
	e.setAge(38);
	e.setSalary(3800);
	System.out.println("第二次修改后:"+e.getName()+"\t"+e.getAge()+"\t"+e.getSalary());
	e.recovery(t.getMemento());//恢复到备忘录保存的对象
	System.out.println("第一次恢复后:"+e.getName()+"\t"+e.getAge()+"\t"+e.getSalary());
	e.recovery(t.getMemento());//恢复到备忘录保存的对象
	System.out.println("第二次恢复后:"+e.getName()+"\t"+e.getAge()+"\t"+e.getSalary());
}