23种设计模式之备忘录模式

场景：

Word文档编辑时，忽然电脑死机，再打开时。可以看到Word提示你恢复到以前的文档

管理系统中，公交撤回功能。公文发送出去后，想撤回来

核心：

就是保存某个对象内部状态的拷贝，这样以后就可以将该对象恢复到原先的状态。

结构：

源发器类Originator

备忘录类Memento

负责人类CareTake

源发器类

public class Emp {
private String ename;
private int age;
private double salary;

public Emp(String ename, int age, double salary) {
this.ename = ename;
this.age = age;
this.salary = salary;
}

//保存数据
public EmpMemento memento() {
return new EmpMemento(this);
}

//恢复数据
public void recovery(EmpMemento memento) {
this.ename = memento.getEname();
this.age = memento.getAge();
this.salary = memento.getSalary();
}

public String getEname() {
return ename;
}

public void setEname(String ename) {
this.ename = ename;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public double getSalary() {
return salary;
}

public void setSala
4000
ry(double salary) {
this.salary = salary;
}
}

备忘录类

/**
* 备忘录类
*/
public class EmpMemento {
private String ename;
private int age;
private double salary;

public EmpMemento(Emp emp) {
this.ename = emp.getEname();
this.age = emp.getAge();
this.salary = emp.getSalary();
}

public String getEname() {
return ename;
}

public void setEname(String ename) {
this.ename = ename;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public double getSalary() {
return salary;
}

public void setSalary(double salary) {
this.salary = salary;
}
}

负责人类

public class CareTaker {
public EmpMemento memento;

public EmpMemento getMemento() {
return memento;
}

public void setMemento(EmpMemento memento) {
this.memento = memento;
}
}