自学多线程-3
中断线程的运行：
当一个线程运行时，另一个线程可以调用对应的Thread对象的interrupt()方法来中断它。
代码示例如下：
class Kirl implements Runnable { public void printText() { System.out.println("Thread1 start sleep"); try { Thread.sleep(5000); } catch(Exception e) { System.out.println("Thread1 block"); return; } System.out.println("Thread1 quit"); } public void run() { printText(); } } public class TestThread { /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { // TODO Auto-generated method stub Kirl k1 = new Kirl(); Thread t1 = new Thread(k1,"Kirl"); System.out.println("Kirl start"); t1.start(); System.out.println("Main sleep"); try { Thread.sleep(3000); } catch (Exception e) { // TODO: handle exception } System.out.println("Main block start"); t1.interrupt(); System.out.println("Main quit"); } } 运行结果如下：
Kirl start Main sleep Thread1 start sleep Main block start Main quit Thread1 block
由以上结果可知，当Thread1线程执行过程中，Main线程发出中断Thread1线程的命令，则Thread1线程被中断，抛出异常。
查看线程的中断状态：
可以在Thread对象上调用isInterrupted()方法来检查任何线程的中断状态。
示例代码如下：
public class TestThread { /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { // TODO Auto-generated method stub Thread t = Thread.currentThread(); System.out.println("Time1:" + t.isInterrupted()); t.interrupt(); System.out.println("Time2:" + t.isInterrupted()); System.out.println("Time3:" + t.isInterrupted()); try { Thread.sleep(2000); System.out.println("Interrupted failed!"); }catch(Exception e) { System.out.println("Interrupted success!"); } System.out.println("Time4:" + t.isInterrupted()); } } 运行结果如下：
Time1:false Time2:true Time3:true Interrupted success! Time4:false
由以上结果可知，线程如果中断之后再休眠，则会清除中断标志。
多线程的同步问题：
代码示例如下：
class Kirl implements Runnable { private int ticket = 7; public synchronized void sell() { while(ticket > 0) { try { Thread.sleep(100); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(Thread.currentThread().getName() + "->" + ticket--); } } public void run() { this.sell(); } } public class TestThread { /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { // TODO Auto-generated method stub Kirl k = new Kirl(); Thread t1 = new Thread(k,"Thread1"); Thread t2 = new Thread(k,"Thread2"); Thread t3 = new Thread(k,"Thread3"); t1.start(); t2.start(); t3.start(); } } 运行结果如下：
Thread1->7 Thread1->6 Thread1->5 Thread1->4 Thread1->3 Thread1->2 Thread1->1
由以上结果可知，虽然实现了多线程共享资源的问题，但只有一个线程在执行，故并不是真正的实现了多线程的同步功能。即只有一个代售点在售票。
class Kirl implements Runnable { private int ticket = 7; public void sell() { while(ticket > 0) { synchronized (this) { if(this.ticket > 0){ try { Thread.sleep(100); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(Thread.currentThread().getName() + "->" + ticket--); } } } } public void run() { this.sell(); } } public class TestThread { /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { // TODO Auto-generated method stub Kirl k = new Kirl(); Thread t1 = new Thread(k,"Thread1"); Thread t2 = new Thread(k,"Thread2"); Thread t3 = new Thread(k,"Thread3"); t1.start(); t2.start(); t3.start(); } } 运行结果如下：
Thread2->7 Thread2->6 Thread3->5 Thread3->4 Thread3->3 Thread1->2 Thread1->1
由结果分析可知，实现了多线程的同步功能，多个代售点功能卖票。
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原始发表：2019-08-25 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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