JDK1.5的新特性互斥鎖（ReentrantLock）學習筆記

1.同步

• 使用ReentrantLock類的lock()和unlock()方法進行同步
  • 2.通信
• 使用ReentrantLock類的newCondition()方法可以獲取Condition對象
• 需要等待的時候使用Condition的await()方法, 喚醒的時候用signal()方法
• 不同的線程使用不同的Condition, 這樣就能區分喚醒的時候找哪個線程了

/**
     * @param args
     */
    public static void main(String[] args) {
        final Printer3 p = new Printer3();

        new Thread() {
            public void run() {
                while(true) {
                    try {
                        p.print1();
                    } catch (InterruptedException e) {

                        e.printStackTrace();
                    }
                }
            }
        }.start();

        new Thread() {
            public void run() {
                while(true) {
                    try {
                        p.print2();
                    } catch (InterruptedException e) {

                        e.printStackTrace();
                    }
                }
            }
        }.start();

        new Thread() {
            public void run() {
                while(true) {
                    try {
                        p.print3();
                    } catch (InterruptedException e) {

                        e.printStackTrace();
                    }
                }
            }
        }.start();
    }

}

class Printer3 {
    private ReentrantLock r = new ReentrantLock();
    private Condition c1 = r.newCondition();
    private Condition c2 = r.newCondition();
    private Condition c3 = r.newCondition();

    private int flag = 1;
    public void print1() throws InterruptedException {                          
        r.lock();                               //獲取鎖
            if(flag != 1) {
                c1.await();
            }
            System.out.print("黑");
            System.out.print("馬");
            System.out.print("程");
            System.out.print("序");
            System.out.print("員");
            System.out.print("\r\n");
            flag = 2;
            //this.notify();                        //隨機喚醒單個等待的線程
            c2.signal();
        r.unlock();                             //釋放鎖
    }

    public void print2() throws InterruptedException {
        r.lock();
            if(flag != 2) {
                c2.await();
            }
            System.out.print("傳");
            System.out.print("智");
            System.out.print("播");
            System.out.print("客");
            System.out.print("\r\n");
            flag = 3;
            //this.notify();
            c3.signal();
        r.unlock();
    }

    public void print3() throws InterruptedException {
        r.lock();
            if(flag != 3) {
                c3.await();
            }
            System.out.print("i");
            System.out.print("t");
            System.out.print("h");
            System.out.print("e");
            System.out.print("i");
            System.out.print("m");
            System.out.print("a");
            System.out.print("\r\n");
            flag = 1;
            c1.signal();
        r.unlock();
    }