/** 
 * 數(shù)據(jù)對(duì)象 
 */ 
public class DataState { 
  private String action; 
 
  public void setAction(String action) { 
    this.action = action; 
  } 
   
  public String getAction() { 
    return action; 
  } 
 
} 

/** 
 * 一個(gè)保存另外一個(gè)對(duì)象內(nèi)部狀態(tài)拷貝 的對(duì)象.這樣以后就可以將該對(duì)象恢復(fù)到原先保存的狀態(tài). 
 */ 
import java.io.File; 
import java.io.Serializable; 
 
public class Memento implements Serializable { 
 
  /*private int number; 
  private File file = null; 
 
  public Memento(Originator o) { 
    this.number = o.getNumber(); 
    this.file = o.getFile(); 
  } 
 
  public int getNumber() { 
    return this.number; 
  } 
 
  public void setNumber(int number) { 
    this.number = number; 
  } 
 
  public File getFile() { 
    return this.file; 
  } 
 
  public void setFile(File file) { 
    this.file = file; 
  } 
*/ 
  private DataState state; 
  public Memento(Originator o) { 
    this.state = o.getState(); 
  } 
   
  public DataState getState() { 
    return state; 
  } 
   
  public void setState(DataState state) { 
    this.state = state; 
  } 
} 

public class Originator { 
 
/* private int number; 
  private File file = null; 
 
  public Originator() { 
 
  } 
 
  // 創(chuàng)建一個(gè)Memento，將自身作為參數(shù)傳入 
  public Memento getMemento() { 
    return new Memento(this); 
  } 
 
  // 從Memento中取出保存的數(shù)據(jù)，恢復(fù)為原始狀態(tài) 
  public void setMemento(Memento m) { 
    number = m.getNumber(); 
    file = m.getFile(); 
  } 
 
  public int getNumber() { 
    return number; 
  } 
 
  public void setNumber(int number) { 
    this.number = number; 
  } 
 
  public File getFile() { 
    return file; 
  } 
 
  public void setFile(File file) { 
    this.file = file; 
  }*/ 
   
  private DataState state; 
  public Originator() { 
     
  } 
   
  public Originator(DataState state) { 
    this.state = state; 
  } 
   
  // 創(chuàng)建一個(gè)Memento，將自身作為參數(shù)傳入 
  public Memento getMemento() { 
    return new Memento(this); 
  } 
   
  // 從Memento中取出保存的數(shù)據(jù)，恢復(fù)為原始狀態(tài) 
  public void setMemento(Memento m) { 
    /* 
     * getMemento() 創(chuàng)建的對(duì)象，保存在某個(gè)容器里， 
     * 當(dāng)需要恢復(fù)時(shí)，將其傳入當(dāng)前方法, 再使用getState(),得出 
     */ 
    this.state = m.getState(); 
  } 
   
  public DataState getState() { 
    return state; 
  } 
   
  public void setState(DataState state) { 
    this.state = state; 
  } 
} 

/* 
 * Originator用于 加載數(shù)據(jù)， 建立Memento對(duì)象，及通過(guò)Memento恢復(fù)原始數(shù)據(jù) 
 */ 
public class Test { 
  public static void main(String[] args) { 
     
//   Originator originator = new Originator(); 
//   originator.setNumber(8); 
//    
//   Memento memento = originator.getMemento(); 
//   System.out.println(memento.getNumber()); 
     
    DataState state = new DataState(); 
    state.setAction("copy a character"); 
    Originator originator = new Originator(); 
    System.out.println("創(chuàng)建原始數(shù)據(jù)"); 
    originator.setState(state); 
     
    System.out.println("創(chuàng)建備忘錄對(duì)象, 保存原始數(shù)據(jù)狀態(tài)"); 
    Memento memento = originator.getMemento(); 
     
    System.out.println("創(chuàng)建了一個(gè)新數(shù)據(jù)"); 
    originator.setState(new DataState()); 
 
    System.out.println("創(chuàng)建新數(shù)據(jù)后：" + originator.getState().getAction()); 
     
    /* 
     * memento 需要保存在某地，需要時(shí)取出，以恢復(fù)它內(nèi)部所保存的數(shù)據(jù) 
     */ 
    System.out.println("創(chuàng)建新數(shù)據(jù)后，恢復(fù)原數(shù)據(jù)"); 
    originator.setMemento(memento); 
    System.out.println(originator.getState().getAction()); 
  } 
} 

創(chuàng)建原始數(shù)據(jù) 
創(chuàng)建備忘錄對(duì)象, 保存原始數(shù)據(jù)狀態(tài) 
創(chuàng)建了一個(gè)新數(shù)據(jù) 
創(chuàng)建新數(shù)據(jù)后：null 
創(chuàng)建新數(shù)據(jù)后，恢復(fù)原數(shù)據(jù) 
copy a character