Observer 观察者

Observer 观察者

需要事件源对象，事件，观察者。观察源中聚合观察者List,
例如AWT（抽象窗口工具包）中的KeyEvent，事件源对象是窗口，事件是各种keyEvent,自定义观察者对象处理各种事件。

  1. public class Observer {
  2.     public static void main(String[] args) {
  3.         Child child = new Child();
  4.         child.setName("XiaoMing");
  5.         Observer1 observer1 = new Observer1();
  6.         Observer2 observer2 = new Observer2();
  7.         child.observersArrayList.add(observer1);
  8.         child.observersArrayList.add(observer2);
  9.         child.cri();
  10.     }
  11. }
  12. class Child{
  13.     String name;
  14.     ArrayList<Observers> observersArrayList = new ArrayList<>();
  15.     public String getName() {
  16.         return name;
  17.     }
  18.     public void setName(String name) {
  19.         this.name = name;
  20.     }
  21.     public void cri(){
  22.         EventPart1 eventPart1 = new EventPart1(this,System.currentTimeMillis());
  23.         System.out.println("Child is cri");
  24.         Iterator<Observers> it = observersArrayList.iterator();
  25.         while(it.hasNext()){
  26.             it.next().action(eventPart1);
  27.         }
  28.     }
  29. }
  30. interface Event<T>{
  31.     T getSource();
  32. }
  33. class EventPart1 implements Event<Child>{
  34.     Child child;
  35.     Long timestamp;
  36.     @Override
  37.     public Child getSource() {
  38.         return child;
  39.     }
  40.     public EventPart1(Child child,Long timestamp){
  41.         this.child=child;
  42.         this.timestamp=timestamp;
  43.     }
  44. }
  45. interface Observers{
  46.     void action(EventPart1 eventPart1);
  47. }
  48. class Observer1 implements Observers{
  49.     @Override
  50.     public void action(EventPart1 eventPart1) {
  51.         System.out.println("Observer1,timestamp:"+eventPart1.timestamp+"Child name:"+eventPart1.child.getName());
  52.     }
  53. }
  54. class Observer2 implements Observers{
  55.     @Override
  56.     public void action(EventPart1 eventPart1) {
  57.         System.out.println("Observer2,timestamp:"+eventPart1.timestamp+"Child name:"+eventPart1.child.getName());
  58.     }
  59. }