备忘录模式

1. 备忘录角色

public class Memento {
    private String state;
    public Memento(String state) {
        this.state = state;
    }
    public String getState() {
        return state;
    }
    public void setState(String state) {
        this.state = state;
    }
}

2. 管理者角色

public class Caretaker {
    private Memento memento;
    public Memento getMemento() {
        return memento;
    }
    public void setMemento(Memento memento) {
        this.memento = memento;
    }
}

3. 发起人角色

public class Originator {
    //备份数据
    private String state;
    public String getState() {
        return state;
    }
    public void setState(String state) {
        this.state = state;
    }
    //创建备份数据
    public Memento createMemento() {
        return new Memento(this.getState());
    }
    //恢复备份数据
    public void restoreMemento(Memento memento) {
        this.setState(memento.getState());
    }
}

4. 场景使用

    //定义发起人角色
    Originator originator =new Originator();
    //创建备份管理者角色
    Caretaker caretaker =new Caretaker();
    //创建备份状态
    caretaker.setMemento(originator.createMemento());
    //恢复备份状态
    originator.restoreMemento(caretaker.getMemento());