轻松掌握Java备忘录模式

/**
 * 目标对象：将要被备忘的对象
 */
class Word {

 private String content;
 private String image;
 private String table;
 public Word(String content, String image, String table) {
 super();
 this.content = content;
 this.image = image;
 this.table = table;
 }
 
 public WordMemento memento(){
 return new WordMemento(this);
 }
 
 public void recovery(WordMemento memento){
 this.content = memento.getContent();
 this.image = memento.getImage();
 this.table = memento.getTable();
 }
 
 public String getContent() {
 return content;
 }
 public void setContent(String content) {
 this.content = content;
 }
 public String getImage() {
 return image;
 }
 public void setImage(String image) {
 this.image = image;
 }
 public String getTable() {
 return table;
 }
 public void setTable(String table) {
 this.table = table;
 }
}

/**
 * 备忘录对象
 */
class WordMemento{
 private String content;
 private String image;
 private String table;
 
 public WordMemento(Word word) {
 this.content = word.getContent();
 this.image = word.getImage();
 this.table = word.getTable();
 }
 public String getContent() {
 return content;
 }
 public void setContent(String content) {
 this.content = content;
 }
 public String getImage() {
 return image;
 }
 public void setImage(String image) {
 this.image = image;
 }
 public String getTable() {
 return table;
 }
 public void setTable(String table) {
 this.table = table;
 }
}
/**
 * 负责人对象：负责记录备忘录对象
 */
class CareTaker{

 private List<WordMemento> list = new ArrayList<>();
 private int index = 0;
 
 public void setMemento(WordMemento memento){
 list.add(memento);
 this.index = list.size();
 }
 
 public WordMemento getWordMemento(){
 if(index == 0){
  System.out.println("没有可还原的内容");
  return null;
 }
 WordMemento memento = list.get(index-1);
 list.remove(index-1);
 index--;
 return memento;
 }
}