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概述
次要用於Java線程裡指定時間或周期運轉義務。Timer是線程平安的，但不提供實時性(real-time)保證。
結構函數
Timer()
默許結構函數。
Timer(boolean)
指定關聯線程能否作為daemon線程。
Timer(String)
指定關聯線程的稱號。
Timer(String, boolean)
同時指定關聯線程的稱號和能否作為daemon。
schdule辦法
schedule(TimerTask task, long delay)
以以後時間為基准，延遲指定的毫秒後執行一次TimerTask義務。
schedule(TimerTask task, Date time)
在指定的日期執行一次TimerTask義務。
假如日期time早於以後時間，則立即執行。
運用示例
public class Demo {
private static Timer timer = new Timer();
public static class MyTask extends TimerTask {
@Override
public void run() {
System.out.println("Run Time：" + new Date().toString());
}
}
public static void main(String[] args) {
try {
MyTask task = new MyTask();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = "2016-12-27 14:36:00";
Date date = sdf.parse(dateStr);
System.out.println("Date = " + date.toString() + " NowTime = " + new Date().toString());
timer.schedule(task, date);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
執行後果
Date = Tue Dec 27 14:36:00 CST 2016 NowTime = Tue Dec 27 21:28:04 CST 2016 Run Time：Tue Dec 27 21:28:04 CST 2016
闡明是立即執行。
schedule(TimerTask task, long delay, long period)
以以後時間為基准，延遲指定的毫秒後，再按指定的時間距離地有限次數的執行TimerTask義務。(fixed-delay execution)
運用示例
public class Demo {
private static Timer timer = new Timer();
public static class MyTask extends TimerTask {
@Override
public void run() {
System.out.println("Run Time: " + new Date().toString());
}
}
public static void main(String[] args) {
MyTask task = new MyTask();
System.out.println("Now Time: " + new Date().toString());
timer.schedule(task, 3000, 5000);
}
}
執行後果
Now Time: Tue Dec 27 21:34:59 CST 2016 Run Time: Tue Dec 27 21:35:02 CST 2016 Run Time: Tue Dec 27 21:35:07 CST 2016 Run Time: Tue Dec 27 21:35:12 CST 2016 Run Time: Tue Dec 27 21:35:17 CST 2016
闡明以以後基准時間延遲3秒後執行一次，當前按指定距離時間5秒有限次數的執行。
schedule(TimerTask task, Date firstTime, long period)
在指定的日期之後，按指定的時間距離地有限次數的執行TimerTask義務。(fixed-delay execution)
假如日期firstTime早於以後時間，則立即執行，且不執行在時間差內的義務。
運用示例
public class Demo {
private static Timer timer = new Timer();
public static class MyTask extends TimerTask {
@Override
public void run() {
System.out.println("Run Time：" + new Date().toString());
}
public static void main(String[] args) {
try {
MyTask task = new MyTask();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = "2016-12-27 14:36:00";
Date date = sdf.parse(dateStr);
System.out.println("Date = " + date.toString() + " NowTime = " + new Date().toString());
timer.schedule(task, date, 3000);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
}
執行後果
Date = Tue Dec 27 14:36:00 CST 2016 NowTime = Tue Dec 27 21:43:30 CST 2016 Run Time：Tue Dec 27 21:43:30 CST 2016 Run Time：Tue Dec 27 21:43:33 CST 2016 Run Time：Tue Dec 27 21:43:36 CST 2016
闡明指定的之間早於以後時間，則立即執行，不會補充時間差內的義務。
scheduleAtFixedRate辦法
scheduleAtFixedRate(TimerTask task, long delay, long period)
以以後時間為基准，延遲指定的毫秒後，再按指定的時間距離周期性地有限次數的執行TimerTask義務。(fixed-rate execution)
運用示例
public class Demo {
private static Timer timer = new Timer();
public static class MyTask extends TimerTask {
@Override
public void run() {
System.out.println("Run Time: " + new Date().toString());
}
}
public static void main(String[] args) {
MyTask task = new MyTask();
System.out.println("Now Time: " + new Date().toString());
timer.scheduleAtFixedRate(task, 3000, 5000);
}
}
執行後果
Now Time: Tue Dec 27 21:58:03 CST 2016 Run Time: Tue Dec 27 21:58:06 CST 2016 Run Time: Tue Dec 27 21:58:11 CST 2016 Run Time: Tue Dec 27 21:58:16 CST 2016 Run Time: Tue Dec 27 21:58:21 CST 2016
闡明以以後基准時間延遲3秒後執行一次，當前按指定距離時間5秒有限次數的執行。
scheduleAtFixedRate(TimerTask task, Date firstTime, long period)
在指定的日期之後，按指定的時間距離周期性地有限次數的執行TimerTask義務。(fixed-rate execution)
假如日期firstTime早於以後時間，則立刻執行，並補充性的執行在時間差內的義務。
運用示例
public class Demo {
private static Timer timer = new Timer();
public static class MyTask extends TimerTask {
@Override
public void run() {
System.out.println("Run Time：" + new Date().toString());
}
public static void main(String[] args) {
try {
MyTask task = new MyTask();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = "2016-12-27 22:02:00";
Date date = sdf.parse(dateStr);
System.out.println("Date = " + date.toString() + " NowTime = " + new Date().toString());
timer.scheduleAtFixedRate(task, date, 5000);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
}
執行後果
Date = Tue Dec 27 22:02:00 CST 2016 NowTime = Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:54 CST 2016 Run Time：Tue Dec 27 22:02:55 CST 2016 Run Time：Tue Dec 27 22:03:00 CST 2016 Run Time：Tue Dec 27 22:03:05 CST 2016
闡明指定的之間早於以後時間，則立即執行。
在時間22:02:00--22:02:54內大約有11個5秒距離，則優先補充性的執行在時間差內的義務，然後在22:02:55補充終了(執行12次。ps：0-55秒區間段內首位都算上，正好觸發12次)，爾後每隔5秒執行一次定時義務。
執行義務延時比照之 schedule 和 scheduleAtFixedRate
schedule不延時
運用示例
public class Demo {
private static Timer timer = new Timer();
private static int runCount = 0;
public static class MyTask extends TimerTask {
@Override
public void run() {
try {
System.out.println("Begin Run Time: " + new Date().toString());
Thread.sleep(3000);
System.out.println("End Run Time: " + new Date().toString());
runCount++;
if (runCount == 3) {
timer.cancel();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
try {
MyTask task = new MyTask();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = "2016-12-27 14:36:00";
Date date = sdf.parse(dateStr);
System.out.println("Date = " + date.toString() + " NowTime = " + new Date().toString());
timer.schedule(task, date, 5000);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
執行後果
早於以後基准時間
Date = Tue Dec 27 14:36:00 CST 2016 NowTime = Tue Dec 27 22:23:37 CST 2016 Begin Run Time: Tue Dec 27 22:23:37 CST 2016 End Run Time: Tue Dec 27 22:23:40 CST 2016 Begin Run Time: Tue Dec 27 22:23:42 CST 2016 End Run Time: Tue Dec 27 22:23:45 CST 2016 Begin Run Time: Tue Dec 27 22:23:47 CST 2016 End Run Time: Tue Dec 27 22:23:50 CST 2016 Process finished with exit code 0
晚於以後基准時間
Date = Tue Dec 27 22:42:00 CST 2016 NowTime = Tue Dec 27 22:41:54 CST 2016 Begin Run Time: Tue Dec 27 22:42:00 CST 2016 End Run Time: Tue Dec 27 22:42:03 CST 2016 Begin Run Time: Tue Dec 27 22:42:05 CST 2016 End Run Time: Tue Dec 27 22:42:08 CST 2016 Begin Run Time: Tue Dec 27 22:42:10 CST 2016 End Run Time: Tue Dec 27 22:42:13 CST 2016 Process finished with exit code 0
不論早還是晚於基准時間，都不停止補償，下一次義務的執行時間參考的是上一次義務的開端時間點來計算。
schedule延時
運用示例
public class Demo {
private static Timer timer = new Timer();
private static int runCount = 0;
public static class MyTask extends TimerTask {
@Override
public void run() {
try {
System.out.println("Begin Run Time: " + new Date().toString());
Thread.sleep(5000);
System.out.println("End Run Time: " + new Date().toString());
runCount++;
if (runCount == 3) {
timer.cancel();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
try {
MyTask task = new MyTask();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = "2016-12-27 22:42:00";
Date date = sdf.parse(dateStr);
System.out.println("Date = " + date.toString() + " NowTime = " + new Date().toString());
timer.schedule(task, date, 3000);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
執行後果
早於以後基准時間
Date = Tue Dec 27 22:42:00 CST 2016 NowTime = Tue Dec 27 22:45:17 CST 2016 Begin Run Time: Tue Dec 27 22:45:17 CST 2016 End Run Time: Tue Dec 27 22:45:22 CST 2016 Begin Run Time: Tue Dec 27 22:45:22 CST 2016 End Run Time: Tue Dec 27 22:45:27 CST 2016 Begin Run Time: Tue Dec 27 22:45:27 CST 2016 End Run Time: Tue Dec 27 22:45:32 CST 2016 Process finished with exit code 0
晚於以後基准時間
Date = Tue Dec 27 22:47:00 CST 2016 NowTime = Tue Dec 27 22:46:27 CST 2016 Begin Run Time: Tue Dec 27 22:47:00 CST 2016 End Run Time: Tue Dec 27 22:47:05 CST 2016 Begin Run Time: Tue Dec 27 22:47:05 CST 2016 End Run Time: Tue Dec 27 22:47:10 CST 2016 Begin Run Time: Tue Dec 27 22:47:10 CST 2016 End Run Time: Tue Dec 27 22:47:15 CST 2016 Process finished with exit code 0
不論早還是晚於以後基准時間，都不停止補償，下一次義務的執行時間都是參考上一次義務完畢的時間點來計算。
scheduleAtFixedRate不延時
運用示例
public class Demo {
private static Timer timer = new Timer();
private static int runCount = 0;
public static class MyTask extends TimerTask {
@Override
public void run() {
try {
System.out.println("Begin Run Time: " + new Date().toString());
Thread.sleep(3000);
System.out.println("End Run Time: " + new Date().toString());
runCount++;
if (runCount == 1000) {
timer.cancel();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
try {
MyTask task = new MyTask();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = "2016-12-27 22:51:42";
Date date = sdf.parse(dateStr);
System.out.println("Date = " + date.toString() + " NowTime = " + new Date().toString());
timer.scheduleAtFixedRate(task, date, 5000);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
執行後果
早於以後基准時間
Date = Tue Dec 27 22:51:42 CST 2016 NowTime = Tue Dec 27 22:51:57 CST 2016 Begin Run Time: Tue Dec 27 22:51:57 CST 2016 End Run Time: Tue Dec 27 22:52:00 CST 2016 Begin Run Time: Tue Dec 27 22:52:00 CST 2016 End Run Time: Tue Dec 27 22:52:03 CST 2016 Begin Run Time: Tue Dec 27 22:52:03 CST 2016 End Run Time: Tue Dec 27 22:52:06 CST 2016 Begin Run Time: Tue Dec 27 22:52:06 CST 2016 End Run Time: Tue Dec 27 22:52:09 CST 2016 Begin Run Time: Tue Dec 27 22:52:09 CST 2016 End Run Time: Tue Dec 27 22:52:12 CST 2016 Begin Run Time: Tue Dec 27 22:52:12 CST 2016 End Run Time: Tue Dec 27 22:52:15 CST 2016 Begin Run Time: Tue Dec 27 22:52:15 CST 2016 End Run Time: Tue Dec 27 22:52:18 CST 2016 Begin Run Time: Tue Dec 27 22:52:18 CST 2016 End Run Time: Tue Dec 27 22:52:21 CST 2016 Begin Run Time: Tue Dec 27 22:52:22 CST 2016 End Run Time: Tue Dec 27 22:52:25 CST 2016 Begin Run Time: Tue Dec 27 22:52:27 CST 2016 End Run Time: Tue Dec 27 22:52:30 CST 2016 Begin Run Time: Tue Dec 27 22:52:32 CST 2016 End Run Time: Tue Dec 27 22:52:35 CST 2016 Begin Run Time: Tue Dec 27 22:52:37 CST 2016 End Run Time: Tue Dec 27 22:52:40 CST 2016 Begin Run Time: Tue Dec 27 22:52:42 CST 2016 End Run Time: Tue Dec 27 22:52:45 CST 2016 Begin Run Time: Tue Dec 27 22:52:47 CST 2016 End Run Time: Tue Dec 27 22:52:50 CST 2016 Begin Run Time: Tue Dec 27 22:52:52 CST 2016 End Run Time: Tue Dec 27 22:52:55 CST 2016 Begin Run Time: Tue Dec 27 22:52:57 CST 2016 End Run Time: Tue Dec 27 22:53:00 CST 2016 Process finished with exit code 0
晚於以後基准時間
Date = Tue Dec 27 22:37:00 CST 2016 NowTime = Tue Dec 27 22:36:06 CST 2016 Begin Run Time: Tue Dec 27 22:37:00 CST 2016 End Run Time: Tue Dec 27 22:37:03 CST 2016 Begin Run Time: Tue Dec 27 22:37:05 CST 2016 End Run Time: Tue Dec 27 22:37:08 CST 2016 Begin Run Time: Tue Dec 27 22:37:10 CST 2016 End Run Time: Tue Dec 27 22:37:13 CST 2016 Process finished with exit code 0
不延時的狀況下，當早於基准時間時，時間差內的執行義務未補償完時，下一次執行義務的時間參考的是上一次執行義務的完畢時間；一旦補償終了（留意粗體時間點），下一次執行義務的時間參考的是上一次執行義務的開端時間；當晚於基准時間時，下一次執行義務的時間參考的是上一次執行義務的開端時間。
scheduleAtFixedRate延時
運用示例
public class Demo {
private static Timer timer = new Timer();
private static int runCount = 0;
public static class MyTask extends TimerTask {
@Override
public void run() {
try {
System.out.println("Begin Run Time: " + new Date().toString());
Thread.sleep(5000);
System.out.println("End Run Time: " + new Date().toString());
runCount++;
if (runCount == 3) {
timer.cancel();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
try {
MyTask task = new MyTask();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateStr = "2016-12-27 22:28:00";
Date date = sdf.parse(dateStr);
System.out.println("Date = " + date.toString() + " NowTime = " + new Date().toString());
timer.scheduleAtFixedRate(task, date, 3000);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
執行後果
早於以後基准時間
Date = Tue Dec 27 23:01:00 CST 2016 NowTime = Tue Dec 27 23:01:19 CST 2016 Begin Run Time: Tue Dec 27 23:01:19 CST 2016 End Run Time: Tue Dec 27 23:01:24 CST 2016 Begin Run Time: Tue Dec 27 23:01:24 CST 2016 End Run Time: Tue Dec 27 23:01:29 CST 2016 Begin Run Time: Tue Dec 27 23:01:29 CST 2016 End Run Time: Tue Dec 27 23:01:34 CST 2016 Begin Run Time: Tue Dec 27 23:01:34 CST 2016 End Run Time: Tue Dec 27 23:01:39 CST 2016
晚於以後基准時間
Date = Tue Dec 27 22:28:00 CST 2016 NowTime = Tue Dec 27 22:27:55 CST 2016 Begin Run Time: Tue Dec 27 22:28:00 CST 2016 End Run Time: Tue Dec 27 22:28:05 CST 2016 Begin Run Time: Tue Dec 27 22:28:05 CST 2016 End Run Time: Tue Dec 27 22:28:10 CST 2016 Begin Run Time: Tue Dec 27 22:28:10 CST 2016 End Run Time: Tue Dec 27 22:28:15 CST 2016 Process finished with exit code 0
延時的狀況下，即便是早於基准時間，由於延時效應，基本不能夠補償終了時間差內的執行義務，故而在延時的狀況下，下一次義務的執行時間都是參考上一次義務完畢的時間來計算。
比照總結
執行義務不延時
執行義務延時
早於以後基准時間
schedule：下一次義務的執行時間參考的是上一次義務的開端時間來計算。 scheduleAtFixedRate：當早於基准時間時，時間差內的執行義務未補償完時，下一次執行義務的時間參考的是上一次義務的完畢時間；一旦補償終了，下一次執行義務的時間參考上一次義務的開端時間來計算。
二者一樣。下一次義務的執行時間都是參考上一次義務的完畢時間來計算。
晚於以後基准時間
二者一樣。下一次義務的執行時間參考的是上一次義務的開端時間來計算。
二者一樣。下一次義務的執行時間都是參考上一次義務的完畢時間來計算。
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