JAVA线程的interrupt-优快云博客

interrupt()只是改变中断状态而已.interrupt()不会中断一个正在运行的线程。这一方法实际上完成的是，给受阻塞的线程抛出一个中断信号，
这样受阻线程就得以退出阻塞的状态。更确切的说，如果线程被Object.wait,Thread.join和Thread.sleep三种方法之一阻塞，那么，它将接收到一个中断异常（InterruptedException），从而提早地终结被阻塞状态。 如果线程没有被阻塞，这时调用interrupt()将不起作用；否则，线程就将得到InterruptedException异常（该线程必须事先预备好处理此状况），接着逃离阻塞状态。 线程A在执行sleep,wait,join时,线程B调用线程A的interrupt方法,的确这一个时候A会有InterruptedException异常抛出来. 但这其实是在sleep,wait,join这些方法内部会不断检查中断状态的值,而自己抛出的InterruptedException。 如果线程A正在执行一些指定的操作时如赋值,for,while,if,调用方法等,都不会去检查中断状态 ,所以线程A不会抛出InterruptedException,而会一直执行着自己的操作. 当线程A终于执行到wait(),sleep(),join()时,才马上会抛出InterruptedException. 若没有调用sleep(),wait(),join()这些方法,即没有在线程里自己检查中断状态自己抛出InterruptedException的话, 那InterruptedException是不会被抛出来的. 具体使用见实例1，实例2。 注意1:当线程A执行到wait(),sleep(),join()时,抛出InterruptedException后，中断状态已经被系统复位了， 线程A调用Thread.interrupted()返回的是false <div style="line-height:25px"> <h4 style="line-height:25px; margin-top:1.25em; margin-right:0px; margin-bottom:0.65em; margin-left:0px; padding-top:0px; padding-right:0px; padding-bottom:0px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial; font-size:1.1em; background-color:rgb(226,226,226); color:rgb(58,58,58)"> public static booleaninterrupted() </h4> <div style="line-height:21px; margin-top:-25px; margin-right:0px; margin-bottom:0px; margin-left:0px; padding-top:0px; padding-right:7px; padding-bottom:0px; padding-left:7px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial; font-size:0.8em; color:rgb(153,153,153); float:right"> <div style="line-height:21px; margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; padding-top:0px; padding-right:0px; padding-bottom:0px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial"> Since:<a rel="nofollow" href="http://developer.android.com/guide/appendix/api-levels.html#level1" style="color:rgb(153,153,153); line-height:21px; text-decoration:none">API Level 1</a> </div> </div> <div style="line-height:23px; margin-top:0.5em; margin-right:0.25em; margin-bottom:0.5em; margin-left:0.25em; padding-top:0px; padding-right:0px; padding-bottom:0px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial"> <div style="line-height:1em; margin-top:0.25em; margin-right:0px; margin-bottom:0.75em; margin-left:0px; padding-top:0px; padding-right:0px; padding-bottom:0px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial"> <p style="line-height:1.3em; margin-top:0.5em; margin-bottom:0.5em; padding-top:0px; padding-bottom:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial"> Returns a<code style="line-height:1em; color:rgb(0,112,0); font-family:monospace">boolean</code>indicating whether the current Thread (<code style="line-height:1em; color:rgb(0,112,0); font-family:monospace">currentThread()</code>) has a pending interrupt request (<code style="line-height:1em; color:rgb(0,112,0); font-family:monospace">true</code>) or not (<code style="line-height:1em; color:rgb(0,112,0); font-family:monospace">false</code>). It also has the side-effect of clearing the flag. </div> <div style="line-height:23px; margin-top:0.5em; margin-right:1em; margin-bottom:0.5em; margin-left:1em; padding-top:0px; padding-right:0px; padding-bottom:0px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial"> <h5 style="line-height:23px; margin-top:1em; margin-right:0px; margin-bottom:0.65em; margin-left:0px; padding-top:0px; padding-right:0px; padding-bottom:0px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial; font-size:1em; color:rgb(58,58,58)"> Returns</h5> <ul style="line-height:1.3em; margin-top:0px; margin-right:0px; margin-bottom:1em; margin-left:1em; padding-top:0px; padding-right:0px; padding-bottom:0px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial; list-style-type:none; list-style-position:initial"><li style="line-height:1.3em; margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; padding-top:0px; padding-right:0px; padding-bottom:2px; padding-left:0px; border-top-width:0px; border-right-width:0px; border-bottom-width:0px; border-left-width:0px; border-style:initial; border-color:initial"> a<code style="line-height:1em; color:rgb(0,112,0); font-family:monospace">boolean</code>indicating the interrupt status</li></ul> </div> </div> </div>

public booleanisInterrupted()

Since: API Level 1

Returns abooleanindicating whether the receiver has a pending interrupt request (true) or not (false)

Returns

abooleanindicating the interrupt status

1.sleep()&interrupt() 线程A正在使用sleep()暂停着:Thread.sleep(100000); 如果要取消他的等待状态,可以在正在执行的线程里(比如这里是B)调用 a.interrupt(); 令线程A放弃睡眠操作,这里a是线程A对应到的Thread实例 当在sleep中时线程被调用interrupt()时,就马上会放弃暂停的状态.并抛出InterruptedException.丢出异常的,是A线程. 2.wait()&interrupt() 线程A调用了wait()进入了等待状态,也可以用interrupt()取消. 不过这时候要小心锁定的问题.线程在进入等待区,会把锁定解除,当对等待中的线程调用interrupt()时 ,会先重新获取锁定,再抛出异常.在获取锁定之前,是无法抛出异常的. 3.join()&interrupt() 当线程以join()等待其他线程结束时,当它被调用interrupt()，它与sleep()时一样,会马上跳到catch块里. 注意，是对谁调用interrupt()方法,一定是调用被阻塞线程的interrupt方法.如在线程a中调用来线程t.join(). 则a会等t执行完后在执行t.join后的代码,当在线程b中调用来a.interrupt()方法,则会抛出InterruptedException，当然join()也就被取消了。 实例1： staticvoidinterruptDemo() { Threadt1=newThread(newInterruptDemoRunnable(),"first"); Threadt2=newThread(newInterruptDemoRunnable(t1),"second"); t1.start(); t2.start(); } classInterruptDemoRunnableimplementsRunnable { longid=0; staticlongcount=0; Threadt; InterruptDemoRunnable() { this(null); } InterruptDemoRunnable(Threadt) { id=count++; this.t=t; } booleanblRun=true; publicvoidrun() {intcnt=0; while(blRun) { if(t!=null) { if(cnt==2) { t.interrupt(); if(t.isInterrupted()) System.out.println("setthethread"+t.getName()+"tobeInterrupted"); } } else { try { Thread.sleep(1000); } catch(InterruptedExceptione) { System.out.println("FirstInterruptedwhensleep"); System.out.println("Interruptedis"+Thread.interrupted());//@1 } try { Thread.sleep(1); } catch(InterruptedExceptione) { System.out.println("secondInterruptedwhensleep"); } } System.out.println(id+"run"+cnt); cnt++; if(cnt==5) { blRun=false; } } System.out.println("thread:"+id+"exit"); } } 注意1:当线程A执行到wait(),sleep(),join()时,抛出InterruptedException后，中断状态已经被系统复位了。 线程AThread.interrupted()返回的是false 实例2： staticvoidinterruptDemo() { Threadt1=newInterruptDemoThread(); t1.setName("t1"); Threadt2=newInterruptDemoThread(t1); t1.setName("t2"); t1.start(); t2.start(); } classInterruptDemoThreadextendsThread { longid=0; staticlongcount=0; Threadt; InterruptDemoThread() { this(null); } InterruptDemoThread(Threadt) { id=count++; this.t=t; } booleanblRun=true; publicvoidrun() {intcnt=0; while(blRun) { if(t!=null) { if(cnt==2) { t.interrupt(); if(t.isInterrupted()) System.out.println("setthethread"+t.getName()+"tobeInterrupted"); } } elseif(isInterrupted())@1 { /*Thread.interrupted();//@2 System.out.println("afterinterrupted(),thestateofInterruptedis"+isInterrupted());*/ try{ Thread.sleep(1); } catch(InterruptedExceptione) { System.out.println("Interruptedwhensleep"); System.out.println("Interruptedis"+Thread.interrupted()); } } Thread.yield(); System.out.println(id+"run"+cnt); cnt++; if(cnt==5) { blRun=false; } } System.out.println("thread:"+id+"exit"); } } 注意1:如果线程被调用了interrupt()，那么如果此次该线程并不在wait(),sleep(),join()时， 下次执行wait(),sleep(),join()时，一样会抛出InterruptedException，当然抛出后该线程的中断状态也回被系统复位。 注意2:我们可以手动的使用Thread.interrupted()来使当前线程的中断状态系统复位（即清除中断状态）