23种设计模式之备忘录模式

备忘录（Memento）：在不破坏封装性的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态。这样以后就可将该对象恢复到原先保存的状态。

 

package designMode.memento;

class Originator {
    private String state;
    
    public Memento createMemento(){
        return new Memento(state);
    }
    
    public void setMemento(Memento memento){
        state = memento.getState();
    }
    
    public void show(){
        System.out.println("State=:"+state);
    }
    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }
}

package designMode.memento;

class Memento {
    private String state;
    
    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public Memento(String state){
        this.state = state;
    }
}

package designMode.memento;

class Caretaker {
    
    private Memento memento;

    public Memento getMemento() {
        return memento;
    }

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

package designMode.memento;

class Test {
    public static void main(String[] args) {
        Originator o = new Originator();
        o.setState("on");
        o.show();
        
        Caretaker c = new Caretaker();
        c.setMemento(o.createMemento());
        
        o.setState("off");
        o.show();
        
        o.setMemento(c.getMemento());
        o.show();
    }
}