定时执行任务

1、java.util.Timer类可以实现这种业务。

定义任务：

import java.util.TimerTask;public class TimeTask extends TimerTask {@Overridepublic void run() {System.out.println("Hello World!");}}

public void execute(){ Timer timer = new Timer(); TimeTask task1 = new TimeTask(); //TimeTask2 task2 = new TimeTask2();Date date = new Date(); long timestamp = 2000; timer.schedule(task1, date, timestamp); //timer.schedule(task2, date, timestamp/2);}

Timer类是线程安全的：多个线程可以共享单个 Timer 对象而无需进行外部同步。 故可以同事执行多个任务！

 

2、Observer处理更合理

定义业务对象抽象类

import java.util.Iterator;import java.util.Vector;public abstract class Generator {private Vector<Observer> Observers = new Vector<Observer>();public void addObserver(Observer observer){Observers.add(observer);}public void deleteObserver(Observer observer){Observers.remove(observer);}public void notifyObservers(){Iterator it = Observers.iterator();while(it.hasNext()){Observer o = (Observer)it.next();o.update(this);}}public abstract void execute();}

业务对象实现类

import java.util.Calendar;public class TimeGenerator extends Generator {@Overridepublic void execute() {//Calendar c = Calendar.getInstance();//if(c.get(Calendar.HOUR_OF_DAY) == 14){notifyObservers();//}}}

 

观察者接口

public interface Observer {public abstract void update(Generator generator);}

public class PrintObserver implements Observer {/** * @author Allen * 状态发生改变时执行的业务 */public void update(Generator generator) {System.out.println("Hello World!");}}

当然也可以建立多个观察者监听该对象，处理多个业务。

public class OutObserver implements Observer {
 public void update(Generator generator) {

  System.out.println("Hi Allen!");
 }
}