在不破坏封装性的前提下，捕捉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。
类图
实现
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| public class Originator {
private String state;
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public Memento createMemento() {
return new Memento(state);
}
public void setMemento(Memento memento) {
state = memento.getState();
}
public void show() {
System.out.println("State=" + state);
}
}
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| public class Memento {
private String state;
public Memento(String state) {
this.state = state;
}
public String getState() {
return state;
}
}
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| public class Caretaker {
private Memento memento;
public Memento getMemento() {
return memento;
}
public void setMemento(Memento memento) {
this.memento = memento;
}
}
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| public class Client {
public static void main(String[] args) {
Originator originator = new Originator();
originator.setState("on");
originator.show();
Caretaker caretaker = new Caretaker();
caretaker.setMemento(originator.createMemento());
originator.setState("off");
originator.show();
originator.setMemento(caretaker.getMemento());
originator.show();
}
}
|