public class ToShortMessage extends ShortMessage {

	public String getFilterMessageBody() {
		this.shortMessageState.setHasRead(true, this);
		return messageBody;
	}

}

public class ShortMessageState extends Observable{

.....

           public void setHasRead(boolean hasRead, ShortMessage shortMessage) {
		this.shortMessage = shortMessage;
		if ((hasRead) && (!this.hasRead)){
			this.hasRead = hasRead;
			setChanged();//出发
			notifyObservers(this);					
		}else
			this.hasRead = hasRead;
		
	}

}
public class ShortMessageRepository implements Observer{
....
         public void update(Observable obj,Object arg){
		logger.debug(" Observable update ");
		ShortMessageState shortMessageState = (ShortMessageState)obj;
		try {
	this.shortMessageDao.updateShortMessate(shortMessageState.getShortMessage());
		} catch (Exception e) {
			e.printStackTrace();
		}
	  }

}