interrupt方法
首先梳理Thread关于interrupt的定义
/** * Interrupts this thread. * * <p> Unless the current thread is interrupting itself, which is * always permitted, the {@link #checkAccess() checkAccess} method * of this thread is invoked, which may cause a {@link * SecurityException} to be thrown. * * <p> If this thread is blocked in an invocation of the {@link * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link * Object#wait(long, int) wait(long, int)} methods of the {@link Object} * class, or of the {@link #join()}, {@link #join(long)}, {@link * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)}, * methods of this class, then its interrupt status will be cleared and it * will receive an {@link InterruptedException}. * * <p&gjst; If this thread is blocked in an I/O operation upon an {@link * Java.nio.channels.InterruptibleChannel InterruptibleChannel} * then the channel will be closed, the thread's interrupt * status will be set, and http://www.devze.comthe thread will receive a {@link * java.nio.channels.ClosedByInterruptException}. * * <p> If this thread is blocked in a {@link java.nio.channels.Selector} * then the thread's interrupt status will be set and it will return * immediately from the selection operation, possibly with a non-zero * value, just as if the selector's {@link * java.nio.channels.Selector#wakeup wakeup} method were invoked. * * <p> If none of the previous conditions hold then this thread's interrupt * staDmxooxtus will be set. </p> * * <p> Interrupting a thread that is not alive need not have any effect. * * @throws SecurityException * if the current thread cannot modify this thread * * @revised 6.0 * @spec jsR-51 */ public void interrupt()
这里讲述了Thread实例对象调用方法interrupt,有这几种情况
? 1.在线程里面有wait,sleep,join方法,会弹出InterruptedException,状态会被清除
? 2.io里面,会弹出异常,状态会被设置,…
? 3.如果线程阻塞在nio中的Selector中,状态会被设置,…
? 4.如果不是上面,这些情况,状态会被设置
可以看出interrupt是关于状态的设置
我们来验证一下
第一种,没有任何情况的
public static void main(String[] args) { Thread t1 = new Thread(()->{ while(true){ if (interrupted()) { brjavascripteak; } System.out.println("i" + new Date()); } }); t1.start(); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } t1.interrupt(); }
线程会在(1000+)ms后结束,整个程序也会结束
第二种,有sleep的情况下
public static void main(String[] args) { Thread t1 = new Thread(()->{ while(true){ if (interrupted()) { break; } try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("i" + new Date()); } }); t1.start(); try { Thread.sleep编程客栈(1000); } catch (InterruptedException e) { e.printStackTrace(); } t1.interrupt(); }
方法并不会退出,只是打出了一个InterruptException
如何处理中断?
- 上文都在介绍如何获取中断状态,那么当我们捕获到中断状态后,究竟如何处理呢?
- Java类库中提供的一些可能会发生阻塞的方法都会抛InterruptedException异常,如:BlockingQueue#put、BlockingQueue#take、Object#wait、Thread#sleep。
- 当你在某一条线程中调用这些方法时,这个方法可能会被阻塞很长时间,你可以在别的线程中调用当前线程对象的interrupt方法触发这些函数抛出InterruptedException异常。
- 当一个函数抛出InterruptedException异常时,表示这个方法阻塞的时间太久了,别人不想等它执行结束了。
- 当你的捕获到一个InterruptedException异常后,亦可以处理它,或者向上抛出。
- 抛出时要注意???:当你捕获到InterruptedException异常后,当前线程的中断状态已经被修改为false(表示线程未被中断);此时你若能够处理中断,则不用理会该值;但如果你继续向上抛InterruptedException异常,你需要再次调用interrupt方法,将当前线程的中断状态设为true。
- 注意:绝对不能“吞掉中断”!即捕获了InterruptedException而不作任何处理。这样违背了中断机制的规则,别人想让你线程中断,然而你自己不处理,也不将中断请求告诉调用者,调用者一直以为没有中断请求。
更新相关interrupt方法的意义
public void interrupt()
Thread里面的打断函数,可以使用新建一个Thread对象,执行thread.interrupt();
修改调用线程的interrupt 的status
public static boolean interrupted()
该方法可以判断是否被打断,但是这个interrupt的status会被清除,
/** * Tests whether the current thread has been interrupted. The * <i>interrupted status</i> of the thread is cleared by this method. In * other words, if this method were to be called twice in succession, the * second call would return false (unless the current thread were * interrupted again, after the first call had cleared its interrupted * status and before the second call had examined it). * * <p>A thread interruption ignored because a thread was not alive * at the time of the interrupt will be reflected by this method * returning false. * * @return <code>true</code> if the current thread has been interrupted; * <code>false</code> otherwise. * @see #isInterrupted() * @revised 6.0 */
public boolean isInterrupted()
该方法可以判断是否被打断
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