多线程(JDK1.5的新特性互斥锁)

多线程(JDK1.5的新特性互斥锁)(掌握)

• 1.同步
  • 使用ReentrantLock类的lock()和unlock()方法进行同步
• 2.通信
  • 使用ReentrantLock类的newCondition()方法可以获取Condition对象
  • 需要等待的时候使用Condition的await()方法, 唤醒的时候用signal()方法
  • 不同的线程使用不同的Condition, 这样就能区分唤醒的时候找哪个线程了

    import java.util.concurrent.locks.Condition;
    import java.util.concurrent.locks.ReentrantLock;

    public class Demo3_ReentrantLock {

    /**
     * @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();                                //获取锁
            if(flag != 1) {
                c1.await();
            }
            System.out.print("黑");
            System.out.print("马");
            System.out.print("程");
            System.out.print("序");
            System.out.print("员");
            System.out.print("\r\n");
            flag = 2;
            //this.notify();                        //随机唤醒单个等待的线程
            c2.signal();
        r.unlock();                                //释放锁
    }
    
    public void print2() throws InterruptedException {
        r.lock();
            if(flag != 2) {
                c2.await();
            }
            System.out.print("传");
            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();
    }
}