21.重入锁ReentrantLock

ReentrantLock

    重入锁，在须要进行代码同步部分上加锁，可是必定要记得解锁。

    类型：公平锁(队列方式进行排队)、非公平锁(按照cpu的分配)，非公平锁性能要比公平锁性能高,默认为非公平锁。

 
 
 
 
 

  
  
  
  
  
   
   
   
   
   

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    
finally内较好，由于解锁锁程序可能会发生一些意想不到的错误，致使没法正常解锁
    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

    
    
    
    
    

   
   
   
   
   
 
 
 
 
 
 
 
 
 package dmeo9;import javax.security.auth.login.FailedLoginException;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;/** * Created by liudan on 2017/8/4. */public class DemoLock { private Lock lock = new ReentrantLock(false); public void m1(){ try { lock.lock(); System.err.println(Thread.currentThread().getName()+"：线程，进入m1"); Thread.sleep(3000); System.err.println(Thread.currentThread().getName()+"：线程，继续执行 m1"); Thread.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); }finally { lock.unlock();//解锁的动做写在 } } public void m2(){ try { lock.lock(); System.err.println(Thread.currentThread().getName()+"：线程，进入m2"); Thread.sleep(3000); System.err.println(Thread.currentThread().getName()+"：线程，继续执行 m2"); Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); }finally { lock.unlock(); } } public static void main(String[] atgs){ final DemoLock demoLock = new DemoLock(); Thread t1 = new Thread(new Runnable() { @Override public void run() { demoLock.m1(); demoLock.m2(); } },"t_00001"); t1.start(); }} 输出：t_00001：线程，进入m1 t_00001：线程，继续执行 m1 t_00001：线程，进入m2 t_00001：线程，继续执行 m2