今天在4.4看见一种比较奇怪的继承方式，不知道是我out了，还是out了
mark吧
public abstract class AtomicOperation implements Serializable {
private static final long serialVersionUID = 1L;
public static final AtomicOperation EXECUTE_ACTIVITY = new ExecuteActivity();
public static final AtomicOperation PROPAGATE_TO_PARENT = new MoveToParentActivity();
public static final AtomicOperation TRANSITION_TAKE = new TransitionTake();
public static final AtomicOperation TRANSITION_START_ACTIVITY = new TransitionStartActivity();
public static final AtomicOperation EXECUTE_EVENT_LISTENER = new ExecuteEventListener();
public static final AtomicOperation TRANSITION_END_ACTIVITY = new TransitionEndActivity();
public abstract boolean isAsync(ExecutionImpl execution);
public abstract MessageImpl createAsyncMessage(ExecutionImpl execution);
public abstract void perform(ExecutionImpl execution);
public static AtomicOperation parseAtomicOperation(String text) {
if (text==null) {
return null;
}
if (TRANSITION_END_ACTIVITY.toString().equals(text)) return TRANSITION_END_ACTIVITY;
if (EXECUTE_EVENT_LISTENER.toString().equals(text)) return EXECUTE_EVENT_LISTENER;
if (EXECUTE_ACTIVITY.toString().equals(text)) return EXECUTE_ACTIVITY;
if (TRANSITION_TAKE.toString().equals(text)) return TRANSITION_TAKE;
if (TRANSITION_START_ACTIVITY.toString().equals(text)) return TRANSITION_START_ACTIVITY;
if (PROPAGATE_TO_PARENT.toString().equals(text)) return PROPAGATE_TO_PARENT;
throw new JbpmException("invalid atomic operation text: "+text);
}
}
在父类里包括六个静态的子类的实例！第一次遇到