Lock是一个接口，为了使用一个Lock对象，需要用到
Lock lock = new ReentrantLock();
与 synchronized (someObject) 类似的，lock()方法，表示当前线程占用lock对象，一旦占用，其他线程就不能占用了。
与 synchronized 不同的是，一旦synchronized 块结束，就会自动释放对someObject的占用。 lock却必须调用unlock方法进行手动释放，为了保证释放的执行，往往会把unlock() 放在finally中进行。
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package multiplethread;import java.text.SimpleDateFormat;import java.util.Date;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;public class TestThread { public static String now() { return new SimpleDateFormat("HH:mm:ss").format(new Date()); } public static void log(String msg) { System.out.printf("%s %s %s %n", now() , Thread.currentThread().getName() , msg); } public static void main(String[] args) { Lock lock = new ReentrantLock(); Thread t1 = new Thread() { public void run() { try { log("线程启动"); log("试图占有对象：lock"); lock.lock(); log("占有对象：lock"); log("进行5秒的业务操作"); Thread.sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); } finally { log("释放对象：lock"); lock.unlock(); } log("线程结束"); } }; t1.setName("t1"); t1.start(); try { //先让t1飞2秒 Thread.sleep(2000); } catch (InterruptedException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } Thread t2 = new Thread() { public void run() { try { log("线程启动"); log("试图占有对象：lock"); lock.lock(); log("占有对象：lock"); log("进行5秒的业务操作"); Thread.sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); } finally { log("释放对象：lock"); lock.unlock(); } log("线程结束"); } }; t2.setName("t2"); t2.start(); }} |