Lock lock = new ReentrantLock();  //實(shí)例化鎖
//lock.lock(); //上鎖
boolean locked = lock.tryLock();  //嘗試上鎖
if(locked){
  try {
    //被鎖定的同步代碼塊，同時(shí)只能被一個(gè)線程執(zhí)行
  }finally {
    lock.unlock(); //放在finally代碼塊中，保證鎖一定會(huì)被釋放
  }
}

public class TestReadWriteLock {
  //可以同時(shí)執(zhí)行3個(gè)線程任務(wù)的線程池
  ExecutorService executor = Executors.newFixedThreadPool(3);
  //讀寫目標(biāo)，寫線程放入數(shù)據(jù)到map，讀線程從map讀取數(shù)據(jù)
  Map<String, String> map = new HashMap<>();
  //讀寫鎖操作對象
  ReadWriteLock lock = new ReentrantReadWriteLock();

  //寫操作函數(shù)
  public void write(){
    executor.submit(() -> { //線程池提交寫操作任務(wù)
      lock.writeLock().lock(); //加寫鎖
      try {
        map.put("key", "val");  //寫數(shù)據(jù)操作
        Thread.sleep(2000);
      } catch (InterruptedException e) {
        e.printStackTrace();
      } finally {
        lock.writeLock().unlock(); //釋放寫鎖
      }
    });
  }

  //讀操作函數(shù)
  public void read(){
    lock.readLock().lock(); //加讀鎖
    System.out.println(Thread.currentThread().getName() + "加讀鎖");
    try {
      System.out.println(map.get("key")); //讀數(shù)據(jù)操作
    } finally {
      lock.readLock().unlock(); //釋放讀鎖
      System.out.println(Thread.currentThread().getName() + "釋放讀鎖");
    }
  }

}

  //測試
  public static void main(String[] args) {
    TestReadWriteLock test = new TestReadWriteLock();
    test.write();  //提交一次寫操作任務(wù)，寫一條數(shù)據(jù)
    Runnable readTask = test::read;  //線程方法read，實(shí)現(xiàn)線程Runnable接口的簡便寫法
    test.executor.submit(readTask);  //讀1次（新讀線程）
    test.executor.submit(readTask);  //讀2次 (新讀線程）
    test.executor.shutdown();
  }