事件通知模板
事件通知与观察者模式类似,参照《Java软件体系结构设计模式标准指南》P258,代码https://github.com/birdstudiocn/design-patterns-example/tree/master/src/38
事件接口
1 2 3 | public interface Listener<T, S> { void listen(T event, S result); } |
事件容器类
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | public class OrderedComposite<S> { private List<S> unordered = new ArrayList<S>(); private List<S> ordered = new ArrayList<S>(); private Comparator<? super S> comparator = new AnnotationAwareOrderComparator(); private List<S> list = new ArrayList<S>(); /** * Public setter for the listeners. * * @param items */ public void setItems(List<? extends S> items) { unordered.clear(); ordered.clear(); for (S s : items) { add(s); } } /** * Register additional item. * * @param item */ public void add(S item) { if (item instanceof Ordered) { if (!ordered.contains(item)) { ordered.add(item); } } else if (AnnotationUtils.isAnnotationDeclaredLocally(Order. class , item.getClass())) { if (!ordered.contains(item)) { ordered.add(item); } } else if (!unordered.contains(item)) { unordered.add(item); } Collections.sort(ordered, comparator); list.clear(); list.addAll(ordered); list.addAll(unordered); } /** * Public getter for the list of items. The {@link Ordered} items come * first, followed by any unordered ones. * * @return an iterator over the list of items */ public Iterator<S> iterator() { return new ArrayList<S>(list).iterator(); } /** * Public getter for the list of items in reverse. The {@link Ordered} items * come last, after any unordered ones. * * @return an iterator over the list of items */ public Iterator<S> reverse() { ArrayList<S> result = new ArrayList<S>(list); Collections.reverse(result); return result.iterator(); } } |
事件注册类
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | public class CompositeListener<T, S> implements Listener<T, S> { private OrderedComposite<ProcessListener<? super T, ? super S>> listeners = new OrderedComposite<ProcessListener<? super T, ? super S>>(); /** * Public setter for the listeners. * * @param itemReadListeners */ public void setListeners(List<? extends Listener<? super T, ? super S>> listeners) { this .listeners.setItems(listeners); } /** * Register additional listener. * * @param itemReaderListener */ public void register(ProcessListener<? super T, ? super S> listener) { listeners.add(listener); } /** * Call the registered listeners in reverse order, respecting and * prioritising those that implement {@link Ordered}. * * @see org.springframework.batch.core.ProcessListener#afterProcess(java.lang.Object, * java.lang.Object) */ @Override public void listen(T item, S result) { for (Iterator<Listener<? super T, ? super S>> iterator = listeners.reverse(); iterator.hasNext();) { Listener<? super T, ? super S> listener = iterator.next(); listener.listen(item, result); } } } |
事件目标实现类,Observable
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | public class ConcreteListenSubject { private CompositeListener<BaseEvent<VO, ResultVO>, BaseResult> listener = new CompositeListener<BaseEvent<VO, ResultVO>, BaseResult>(); public void registerListener( ProcessListener<BaseProcessEvent<VO, ResultVO>, BaseResult> listener) { this .listener.register(listener); } public ResultVO process(VO vo) throws Exception { BaseEvent<VO, ResultVO> event = new BaseEvent<VO, ResultVO>(vo,resultVO); listener.afterProcess(event, result); return resultVO; } } |
事件观察实现,Observer
1 2 3 4 5 6 7 | ConcreteListenSubject subject= new ConcreteListenSubject (); subject.registerListener( new Listener() { @Override public void listen(Object event, Object result) { // TODO Auto-generated method stub } }); |
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