Timer和ScheduledExecutorService区别
Timer特点：
1、一个Timer只占用一个线程
timer有多个timerTask的情况，如果一个timerTask有执行时间过长，其它的timerTask就会被耽误
2、如果TimerTask抛出未检查的异常，Timer会由于该异常导致中断。后续的TimerTask任务也不会执行
示例：
1 import java.util.Date; 2 import java.util.Timer; 3 import java.util.TimerTask; 4 5 public class TimerTest extends TimerTask { 6 7 private String jobName = "" ; 8 9 public TimerTest(String jobName) { 10 super(); 11 this.jobName = jobName; 12 } 13 14 int count = 0; 15 16 @Override 17 public void run() { 18 System. out.println(jobName + " " + new Date() + " beep " + (++count)); 19 try { 20 if (jobName .equals("job1" )) { 21 Thread. sleep(1000); 22 throw new RuntimeException(); 23 } 24 25 } catch (InterruptedException e) { 26 // TODO Auto-generated catch block 27 e.printStackTrace(); 28 } 29 } 30 31 public static void main(String[] args) { 32 Timer timer = new Timer(); 33 long period = 2000; 34 // 从现在开始 1 秒钟之后，每隔 2秒钟执行一次 job1 35 timer.schedule( new TimerTest("job1" ), 0, period); 36 // 每隔 2 秒钟执行一次 job2 37 timer.schedule( new TimerTest("job2" ), 0, period); 38 } 39 } 40 执行结果 41 job1 Tue Apr 08 23:37:17 CST 2014 beep 1 42 Exception in thread "Timer-0" java.lang.RuntimeException 43 at TimerTest.run( TimerTest.java:20) 44 at java.util.TimerThread.mainLoop( Timer.java:512) 45 at java.util.TimerThread.run( Timer.java:462)
ScheduledExecutorService(实现类ScheduledThreadPoolExecutor)特点：
1、ScheduledExecutorService是多线程
只要线程池不设置为1，每个线程任务都能按照各自的频率执行。
2、如果线程任务抛出未检查的异常，ScheduledExecutorService只是中断该线程任务，其它任务正常执行
示例：
1 import static java.util.concurrent.TimeUnit.SECONDS; 2 import java.util.Date; 3 import java.util.TimerTask; 4 import java.util.concurrent.Executors; 5 import java.util.concurrent.ScheduledExecutorService; 6 import java.util.concurrent.ScheduledFuture; 7 8 public class TestScheduledThread extends TimerTask { 9 10 private String jobName = "" ; 11 12 public TestScheduledThread(String jobName) { 13 super(); 14 this.jobName = jobName; 15 } 16 17 int count = 0; 18 19 @Override 20 public void run() { 21 System. out.println(jobName + " " + new Date() + " beep " + (++count)); 22 try { 23 if (jobName .equals("job1" )) { 24 Thread. sleep(1000); 25 throw new RuntimeException(); 26 } 27 28 } catch (InterruptedException e) { 29 // TODO Auto-generated catch block 30 e.printStackTrace(); 31 } 32 } 33 34 public static void main(String[] args) { 35 final ScheduledExecutorService scheduler = Executors 36 . newScheduledThreadPool(2); 37 //每隔2秒运行一次 38 final ScheduledFuture beeperHandle = scheduler.scheduleAtFixedRate( 39 new TimerTest("job1" ), 0, 2, SECONDS); 40 //每隔2秒运行一次 41 final ScheduledFuture beeperHandle2 = scheduler.scheduleAtFixedRate( 42 new TimerTest("job2" ), 0, 2, SECONDS); 43 } 44 }
执行结果：
job2 Tue Apr 08 23:42:58 CST 2014 beep 1
job1 Tue Apr 08 23:42:58 CST 2014 beep 1
job2 Tue Apr 08 23:43:00 CST 2014 beep 2
job2 Tue Apr 08 23:43:02 CST 2014 beep 3
job2 Tue Apr 08 23:43:04 CST 2014 beep 4
job2 Tue Apr 08 23:43:06 CST 2014 beep 5
job2 Tue Apr 08 23:43:08 CST 2014 beep 6
