下面为一段标准的Timer用法
private void runTimer(){ Log.d("bloguan", "run:" + Thread.currentThread().getId()); new Timer().schedule(new TimerTask() { @Override public void run() { Log.d("bloguan", "begin:" + Thread.currentThread().getId()); Log.d("bloguan", "end:" + Thread.currentThread().getId()); } },1000, 5000); }
执行结果
11-06 11:25:04.105 2385-2385/com.bloguan.demo D/bloguan: run:1 11-06 11:25:05.106 2385-2410/com.bloguan.demo D/bloguan: begin:139 11-06 11:25:05.106 2385-2410/com.bloguan.demo D/bloguan: end:139 11-06 11:25:10.108 2385-2410/com.bloguan.demo D/bloguan: begin:139 11-06 11:25:10.108 2385-2410/com.bloguan.demo D/bloguan: end:139
分析:Timer延时1秒执行,每5秒循环一次,TimerTask的run运行在子线程
那么,有个疑问,如果run里面执行耗时操作,每5秒的循环周期还准吗?
试一下,我们在run中加一个2秒“耗时操作”
private void runTimer(){ Log.d("bloguan", "run:" + Thread.currentThread().getId()); new Timer().schedule(new TimerTask() { @Override public void run() { Log.d("bloguan", "begin:" + Thread.currentThread().getId()); try { Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); } Log.d("bloguan", "end:" + Thread.currentThread().getId()); } },1000, 5000); }
执行结果
11-06 11:30:27.947 2496-2496/com.bloguan.demo D/bloguan: run:1 11-06 11:30:28.948 2496-2514/com.bloguan.demo D/bloguan: begin:143 11-06 11:30:30.956 2496-2514/com.bloguan.demo D/bloguan: end:143 11-06 11:30:33.949 2496-2514/com.bloguan.demo D/bloguan: begin:143 11-06 11:30:35.949 2496-2514/com.bloguan.demo D/bloguan: end:143 11-06 11:30:38.951 2496-2514/com.bloguan.demo D/bloguan: begin:143 11-06 11:30:40.952 2496-2514/com.bloguan.demo D/bloguan: end:143
分析:定时器仍然每5秒触发一次,run里面的2秒耗时操作不会叠加到5秒这个周期上
如果耗时操作大于period这个周期呢?
把上面代码中的sleep改为6秒
Thread.sleep(6000);
执行结果
11-06 11:43:22.544 2586-2586/com.bloguan.demo D/bloguan: run:1 11-06 11:43:23.546 2586-2604/com.bloguan.demo D/bloguan: begin:147 11-06 11:43:29.546 2586-2604/com.bloguan.demo D/bloguan: end:147 11-06 11:43:29.546 2586-2604/com.bloguan.demo D/bloguan: begin:147 11-06 11:43:35.593 2586-2604/com.bloguan.demo D/bloguan: end:147 11-06 11:43:35.593 2586-2604/com.bloguan.demo D/bloguan: begin:147
分析:Timer的周期先到,但run没执行完,会等到执行完成后再次循环
结论:
1、TimerTask的run运行在子线程,非UI线程
2、如果TimerTask的run中有耗时操作
当耗时操作小于period周期时,仍以period时间为准进行周期循环
当耗时操作大于period周期时,等run执行完后,立即进行下一次
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