Java设计模式之备忘录模式_动力节点Java学院

class Originator { 
  private String state = ""; 
  public String getState() { 
    return state; 
  } 
  public void setState(String state) { 
    this.state = state; 
  } 
  public Memento createMemento(){ 
    return new Memento(this.state); 
  } 
  public void restoreMemento(Memento memento){ 
    this.setState(memento.getState()); 
  } 
} 
class Memento { 
  private String state = ""; 
  public Memento(String state){ 
    this.state = state; 
  } 
  public String getState() { 
    return state; 
  } 
  public void setState(String state) { 
    this.state = state; 
  } 
} 
class Caretaker { 
  private Memento memento; 
  public Memento getMemento(){ 
    return memento; 
  } 
  public void setMemento(Memento memento){ 
    this.memento = memento; 
  } 
} 
public class Client { 
  public static void main(String[] args){ 
    Originator originator = new Originator(); 
    originator.setState("状态1"); 
    System.out.println("初始状态:"+originator.getState()); 
    Caretaker caretaker = new Caretaker(); 
    caretaker.setMemento(originator.createMemento()); 
    originator.setState("状态2"); 
    System.out.println("改变后状态:"+originator.getState()); 
    originator.restoreMemento(caretaker.getMemento()); 
    System.out.println("恢复后状态:"+originator.getState()); 
  } 
} 

class Originator { 
  private String state1 = ""; 
  private String state2 = ""; 
  private String state3 = ""; 
  public String getState1() { 
    return state1; 
  } 
  public void setState1(String state1) { 
    this.state1 = state1; 
  } 
  public String getState2() { 
    return state2; 
  } 
  public void setState2(String state2) { 
    this.state2 = state2; 
  } 
  public String getState3() { 
    return state3; 
  } 
  public void setState3(String state3) { 
    this.state3 = state3; 
  } 
  public Memento createMemento(){ 
    return new Memento(BeanUtils.backupProp(this)); 
  } 
  public void restoreMemento(Memento memento){ 
    BeanUtils.restoreProp(this, memento.getStateMap()); 
  } 
  public String toString(){ 
    return "state1="+state1+"state2="+state2+"state3="+state3; 
  } 
} 
class Memento { 
  private Map<String, Object> stateMap; 
  public Memento(Map<String, Object> map){ 
    this.stateMap = map; 
  } 
  public Map<String, Object> getStateMap() { 
    return stateMap; 
  } 
  public void setStateMap(Map<String, Object> stateMap) { 
    this.stateMap = stateMap; 
  } 
} 
class BeanUtils { 
  public static Map<String, Object> backupProp(Object bean){ 
    Map<String, Object> result = new HashMap<String, Object>(); 
    try{ 
      BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass()); 
      PropertyDescriptor[] descriptors = beanInfo.getPropertyDescriptors(); 
      for(PropertyDescriptor des: descriptors){ 
        String fieldName = des.getName(); 
        Method getter = des.getReadMethod(); 
        Object fieldValue = getter.invoke(bean, new Object[]{}); 
        if(!fieldName.equalsIgnoreCase("class")){ 
          result.put(fieldName, fieldValue); 
        } 
      } 
    }catch(Exception e){ 
      e.printStackTrace(); 
    } 
    return result; 
  } 
  public static void restoreProp(Object bean, Map<String, Object> propMap){ 
    try { 
      BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass()); 
      PropertyDescriptor[] descriptors = beanInfo.getPropertyDescriptors(); 
      for(PropertyDescriptor des: descriptors){ 
        String fieldName = des.getName(); 
        if(propMap.containsKey(fieldName)){ 
          Method setter = des.getWriteMethod(); 
          setter.invoke(bean, new Object[]{propMap.get(fieldName)}); 
        } 
      } 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
} 
class Caretaker { 
  private Map<String, Memento> memMap = new HashMap<String, Memento>(); 
  public Memento getMemento(String index){ 
    return memMap.get(index); 
  } 
  public void setMemento(String index, Memento memento){ 
    this.memMap.put(index, memento); 
  } 
} 
class Client { 
  public static void main(String[] args){ 
    Originator ori = new Originator(); 
    Caretaker caretaker = new Caretaker(); 
    ori.setState1("中国"); 
    ori.setState2("强盛"); 
    ori.setState3("繁荣"); 
    System.out.println("===初始化状态===\n"+ori); 
    caretaker.setMemento("001",ori.createMemento()); 
    ori.setState1("软件"); 
    ori.setState2("架构"); 
    ori.setState3("优秀"); 
    System.out.println("===修改后状态===\n"+ori); 
    ori.restoreMemento(caretaker.getMemento("001")); 
    System.out.println("===恢复后状态===\n"+ori); 
  } 
}