Java并发包--ReentrantLock

Java并发包–ReentrantLock

Java的线程安全，除了基本的同步锁以外，Jdk还为开发者提供了各种同步控制工具，如ReentrantLock，位于java.util.concurrent.locks包下的同步锁工具。

1. 可重入
   拿几次lock，就需要释放几次。

   package com.borderxlab.concurrent.locks.reentrantlock;
   
   import java.util.concurrent.locks.ReentrantLock;
   
   public class ReenterLock implements Runnable {
       public static ReentrantLock lock = new ReentrantLock();
       public static int i = 0;
   
       @Override
       public void run() {
         for (int j = 0; j < 10000; j ++) {
           lock.lock();
           lock.lock();
           try {
             i ++;
           } finally {
             lock.unlock();
             lock.unlock();
           }
         }
       }
   
       public static void main(String[] args) throws InterruptedException {
         ReenterLock r = new ReenterLock();
         Thread t1 = new Thread(r);
         Thread t2 = new Thread(r);
         t1.start();
         t2.start();
         t1.join();
         t2.join();
         System.out.println(i);
       }
   }

2. 可中断

3. 可限时

4. 公平锁