多線程27 -- ReentrantLock

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1.

 1 /** 2  * lock.getHoldCount()方法：只能在當前調用線程內部使用，不能再其他線程中使用 3  * 那麼我可以在m1方法裡去調用m2方法，同時m1方法和m2方法都持有lock鎖定即可 測試結果holdCount數遞增 4  * 5  */ 6 public class TestHoldCount { 7  8     //重入鎖 9     private ReentrantLock lock = new ReentrantLock();10     11     public void m1(){12         try {13             lock.lock();14             System.out.println("進入m1方法，holdCount數為：" + lock.getHoldCount());15             16             //調用m2方法17             m2();18             19         } catch (Exception e) {20             e.printStackTrace();21         } finally {22             lock.unlock();23         }24     }25     26     public void m2(){27         try {28             lock.lock();29             System.out.println("進入m2方法，holdCount數為：" + lock.getHoldCount());30         } catch (Exception e) {31             e.printStackTrace();32         } finally {33             lock.unlock();34         }35     }36     37     38     public static void main(String[] args) {39         TestHoldCount thc = new TestHoldCount();40         thc.m1();41         /*42         進入m1方法，holdCount數為：143         進入m2方法，holdCount數為：2 */44     }45 }

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 2.

 1 public class UseReentrantLock { 2      3     private Lock lock = new ReentrantLock(); 4      5     public void method1(){ 6         try { 7             lock.lock(); 8             System.out.println("當前線程:" + Thread.currentThread().getName() + "進入method1.."); 9             Thread.sleep(1000);10             System.out.println("當前線程:" + Thread.currentThread().getName() + "退出method1..");11             Thread.sleep(1000);12         } catch (InterruptedException e) {13             e.printStackTrace();14         } finally {15             16             lock.unlock();17         }18     }19     20     public void method2(){21         try {22             lock.lock();23             System.out.println("當前線程:" + Thread.currentThread().getName() + "進入method2..");24             Thread.sleep(2000);25             System.out.println("當前線程:" + Thread.currentThread().getName() + "退出method2..");26             Thread.sleep(1000);27         } catch (InterruptedException e) {28             e.printStackTrace();29         } finally {30             31             lock.unlock();32         }33     }34     35     public static void main(String[] args) {36 37         final UseReentrantLock ur = new UseReentrantLock();38         Thread t1 = new Thread(new Runnable() {39             @Override40             public void run() {41                 ur.method1(); //同一把鎖 ur42                 ur.method2(); //同一把鎖 ur43             }44         }, "t1");45 46         t1.start();47         try {48             Thread.sleep(10);49         } catch (InterruptedException e) {50             e.printStackTrace();51         }52         //System.out.println(ur.lock.getQueueLength());53     }54     /*55     當前線程:t1進入method1..56     當前線程:t1退出method1..57     當前線程:t1進入method2..58     當前線程:t1退出method2.. */59     60 }

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多線程27 -- ReentrantLock