> For the complete documentation index, see [llms.txt](https://blakes-organization.gitbook.io/rainsister/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blakes-organization.gitbook.io/rainsister/design-pattern/memento-pattern.md).

# Memento Pattern

일반적으로 개체의 특정 상태를 저장하여 적절한 시간에 개체를 복원할 수 있도록 할때 사용할수 있음. 키보드에서 ctrl + z 기능과 같은거?

아래 예시를 보면 A 에 다양한 속성이 있으며 A는 필요를 결정할수 있음. Backup 속성인 메모 클래스 B는 A의 일부 내부상태를 저장하고 클래스 C는 메모를 저장만 하고 수정불가.

## 코드예시

```java
public class Original {
	
	private String value;
	
	public String getValue() {
		return value;
	}
 
	public void setValue(String value) {
		this.value = value;
	}
 
	public Original(String value) {
		this.value = value;
	}
 
	public Memento createMemento(){
		return new Memento(value);
	}
	
	public void restoreMemento(Memento memento){
		this.value = memento.getValue();
	}
}
```

```java
public class Memento {
	
	private String value;
 
	public Memento(String value) {
		this.value = value;
	}
 
	public String getValue() {
		return value;
	}
 
	public void setValue(String value) {
		this.value = value;
	}
}
```

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

```java
public class Test {
 
	public static void main(String[] args) {
		
		Original origi = new Original("egg");
 
		Storage storage = new Storage(origi.createMemento());
 
		System.out.println("초기화 상태：" + origi.getValue());
		origi.setValue("niu");
		System.out.println("수정후 상태：" + origi.getValue());
 
		origi.restoreMemento(storage.getMemento());
		System.out.println("되돌린후 최종 상태：" + origi.getValue());
	}
}
```


---

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