ReentrantLock
ReentrantLock可以等同于synchronized使用。
ReentrantLock 类实现了Lock ，它拥有与 synchronized 相同的并发性和内存语义，但是添加了类似锁投票、定时锁等候和可中断锁等候的一些特性。此外，它还提供了在激烈争用情况下更佳的性能。（换句话说，当许多线程都想访问共享资源时，JVM 可以花更少的时候来调度线程，把更多时间用在执行线程上。
Condition
线程之间的通信。Condition 将 Object 监视器方法（wait、notify 和 notifyAll）分解成截然不同的对象，以便通过将这些对象与任意 Lock 实现组合使用。
请看demo：
/** * 子线程 和 主线程 协助工作 * * main 打印一次 * sub 打印2次 * * @ClassName: ThreadMutex * @Description: TODO(这里用一句话描述这个类的作用) * @author ZhangWei * @date 2015年8月17日 下午5:24:54 * */ public class ThreadMutexByThreeThread { public static void main(String[] args) { final Buiness2 b = new Buiness2(); new Thread(){ @Override public void run() { for (int i = 1; i <= 50; i++) { b.sub1(); } } }.start(); new Thread(){ @Override public void run() { for (int i = 1; i <= 50; i++) { b.sub2(); } } }.start(); for (int i = 1; i <= 50; i++) { b.main(); } } } class Buiness2{ /** * * 1 main 走 * 2 sub1 走 * 3 sub2 走 * */ private int shouldWho = 0; private Lock lock = new ReentrantLock(); private Condition con1 = lock.newCondition(); private Condition con2 = lock.newCondition(); private Condition con3 = lock.newCondition(); public void sub1(){ lock.lock(); try { while(shouldWho !=1 ){ try { // this.wait(); con2.await(); } catch (Exception e) { e.printStackTrace(); } } for (int j = 1; j <= 2; j++) { System.out.println("sub1 Thread sequnced:"+j); } shouldWho = 2; con3.signal(); } catch (Exception e) { e.printStackTrace(); } finally{ lock.unlock(); } } public void sub2(){ lock.lock(); try { while( shouldWho != 2 ){ try { // this.wait(); con3.await(); } catch (Exception e) { e.printStackTrace(); } } for (int j = 1; j <= 2; j++) { System.out.println("sub2 Thread sequnced:"+j); } shouldWho = 0; con1.signal(); } catch (Exception e) { e.printStackTrace(); } finally{ lock.unlock(); } } public void main(){ lock.lock(); try { while( shouldWho != 0 ){ try { con1.await(); } catch (Exception e) { e.printStackTrace(); } } for (int j = 1; j <= 1; j++) { System.out.println("main Thread sequnced:"+j); } shouldWho = 1; //this.notify(); con2.signal(); } catch (Exception e) { e.printStackTrace(); } finally{ lock.unlock(); } } }