JAvaコールバックメカニズムの実現
6599 ワード
Javaのインタフェースサポートは,コールバックの等価機能を得るメカニズムを提供する.そのテクニックは、簡単なインタフェースを定義し、呼び出す方法を宣言することです.インスタンスがインタフェースの参照を持つことを特徴とします.
たとえば、ある時間に発生したときに通知を望んでいるとします.インタフェースを定義できます.
package com.wxy.callback;
public interface InterestingEvent {
/**
* ， ， ，
*/
public void interestingEvent();
}
これにより、インタフェースを実装するクラスを任意のオブジェクトに制御することができます.したがって、外部タイプの情報に関心を持つ必要はありません.イベント信号を送信するクラスは、InterestingEventインタフェースが実装されたオブジェクトを待機し、適切なタイミングでinterestingEvent()メソッドを呼び出す必要があります.
package com.wxy.callback;
public class EventNotifier {
/** */
private InterestingEvent ie;
/** */
private boolean somethingHappend;
/**
* ，
* @param event
*/
public EventNotifier(InterestingEvent event) {
this.ie = event;
//
somethingHappend = false;
}
/**
* ， InterestingEvent
*/
public void doWork() {
//
if (somethingHappend) {
//
ie.interestingEvent();
}
}
}public class CallMe implements InterestingEvent {
private EventNotifier en;
/**
* ，
*/
public CallMe() {
this.en = new EventNotifier(this);
}
/**
*
*/
@Override
public void interestingEvent() {
System.out.println("oh,something interesting has happended!");
System.out.println("do some action!");
}
public EventNotifier getEn() {
return en;
}
public void setEn(EventNotifier en) {
this.en = en;
}
}package com.wxy.callback;
public interface Event {
/**
*
* @return
*/
public String happendEvent();
}package com.wxy.callback;
public class EventA implements Event {
@Override
public String happendEvent() {
return "job has been finished!";
}
}
package com.wxy.callback;
public class EventB implements Event {
@Override
public String happendEvent() {
return "job has been finished!";
}
}package com.wxy.callback;
public class Boss {
private String name;
public Boss(String name) {
this.name = name;
}
public void getStaffEvent(Staff staff, Event event) {
System.out.println("the msg what the boss received is--" + staff.getName() + ":"
+ event.happendEvent());
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}package com.wxy.callback;
public class Staff {
private Event event; //
private String name; //
private Boss boss; //
/**
*
* @param name
* @param boss Boss ，
*/
public Staff(String name, Boss boss) {
this.name = name;
this.boss = boss;
}
public void doWork() {
System.out.println(name + " is doing working...");
//do somtething.....
for (int i = 0; i < 10; i++) {
System.out.println("sheep" + i);
}
System.out.println(name + " was finished work!");
//tell the boss what has happend, boss
boss.getStaffEvent(this, event);
}
public Event getEvent() {
return event;
}
public void setEvent(Event event) {
this.event = event;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Boss getBoss() {
return boss;
}
public void setBoss(Boss boss) {
this.boss = boss;
}
}
package com.wxy.callback;
public class StaffBossTest {
public static void main(String args[]) {
//
Boss boss = new Boss("boss");
Staff staffA = new Staff("staffA", boss);
Staff staffB = new Staff("staffB", boss);
//
Event event1 = new EventA();
Event event2 = new EventB();
//
staffA.setEvent(event1);
staffB.setEvent(event2);
// ，
staffA.doWork();
staffB.doWork();
}
}staffA was finished work!
the msg what the boss received is--staffA:job has been finished!
staffB is doing working...
sheep0
sheep1
sheep2
sheep3
sheep4
sheep5
sheep6
sheep7
sheep8
sheep9
staffB was finished work!
the msg what the boss received is--staffB:job has been finished!