重学JAVA基础(六):多线程的同步

1.synchronized关键字

/**
 * 同步关键字
 * @author tomsnail
 * @date 2015年4月18日 下午12:12:39
 */
public class SyncThreadTest {

    private static final byte[] lock = new byte[1];

    /**
     * 同步方法
     * @author tomsnail
     * @date 2015年4月18日 下午12:15:30
     */
    public synchronized void test1(){

    }

    /**
     * 同步块
     * @author tomsnail
     * @date 2015年4月18日 下午12:15:17
     */
    public void test2(){
        synchronized (lock) {

        }
    }

}

2.volatile关键字

/**
 * volatile关键字
 * @author tomsnail
 * @date 2015年4月18日 下午12:21:58
 */
public class VolatileThreadTest {

    private volatile int count = 100;

    public void add(int number){
        count+=number;
    }

    public int getCount(){
        return count;
    }
}

3.Lock锁

/**
 * lock锁
 * @author tomsnail
 * @date 2015年4月18日 下午12:58:49
 */
public class LockThreadTest {

    private Lock lock = new ReentrantLock();

    private int count = 100;

    public void test(){
        lock.lock();
        count++;
        System.out.println(count);
        lock.unlock();
    }

}

4.Mutex信号量

/**
 * 线程信号量
 * @author tomsnail
 * @date 2015年4月18日 下午1:14:47
 */
public class MutexThreadTest {

    private CountDownLatch countDownLatch = new CountDownLatch(1);

    private Semaphore s = new Semaphore(5);

    public void a(){
        try {
            countDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void b(){
        countDownLatch.countDown();
    }

    public void c(){
        try {
            System.out.println(" try acquire s");
            s.acquire();
            System.out.println(" acquire s");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void d(){
        s.release();
        System.out.println(" release s");
    }

    public static void main(String[] args) {
        MutexThreadTest mutexThreadTest = new MutexThreadTest();
        for(int i=0;i<10;i++){
            new Thread(new ThreadTest(mutexThreadTest)).start();
        }
        mutexThreadTest.a();
        System.out.println("a...");
        for(int i=0;i<10;i++){
            new Thread(new ThreadTest2(mutexThreadTest)).start();
        }

    }

}
class ThreadTest implements Runnable{

    private MutexThreadTest mutexThreadTest;

    public ThreadTest(MutexThreadTest mutexThreadTest){
        this.mutexThreadTest = mutexThreadTest;
    }

    @Override
    public void run() {
        try {
            Thread.currentThread().sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("mutexThreadTest countDown");
        mutexThreadTest.b();
    }

}

class ThreadTest2 implements Runnable{

    private MutexThreadTest mutexThreadTest;

    public ThreadTest2(MutexThreadTest mutexThreadTest){
        this.mutexThreadTest = mutexThreadTest;
    }

    @Override
    public void run() {
        mutexThreadTest.c();
        try {
            Thread.currentThread().sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        mutexThreadTest.d();
    }

}