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

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public interface Listener<T, S> {     void listen(T event, S result); }

事件容器类

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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

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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

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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

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ConcreteListenSubject subject=new ConcreteListenSubject (); subject.registerListener(new Listener() {     @Override     public void listen(Object event, Object result) {     // TODO Auto-generated method stub             } });