生产者与消费者(一)

来源：互联网发布：中央财经大学知乎编辑：程序博客网时间：2024/06/06 20:21

首先谈下wait(),notify(),notifyAll(),这个三个方法都是Object里的方法，具体详细作用可以查看API文档:

wait():

/**     * Causes the current thread to wait until another thread invokes the     * {@link java.lang.Object#notify()} method or the     * {@link java.lang.Object#notifyAll()} method for this object, or     * some other thread interrupts the current thread, or a certain     * amount of real time has elapsed.     * <p>

notify():

/**     * Wakes up a single thread that is waiting on this object's     * monitor. If any threads are waiting on this object, one of them     * is chosen to be awakened. The choice is arbitrary and occurs at     * the discretion of the implementation. A thread waits on an object's     * monitor by calling one of the {@code wait} methods.     * <p>

且这三个方法都是native方法。简单的说明这三个方法作用:

如果对象调用了wait方法就会使持有该对象的线程把该对象的控制权交出去，然后处于等待状态。

如果对象调用了notify方法就会通知某个正在等待这个对象的控制权的线程可以继续运行。
如果对象调用了notifyAll方法就会通知所有等待这个对象控制权的线程继续运行。

关于synchronize与volatile参考之前的文章http://blog.csdn.net/bat_os/article/details/53040490

简单分析下生产者与消费者之间的关系，比如厨师就是生产者，顾客是消费者，服务员按照厨师做好菜的顺序把菜送达。下面用wait,notify解决该问题:

public class Task implements Runnable {    private volatile static int i = 0;    public void run() {                System.out.println("任务" + ++i + "执行完");    }}

/** * Created by diy_os on 2016/11/6. */public class ThreadPool {    private static  int workThreadNum = 3;    private volatile static int FINISH_TASK = 0;    private WorkerThread workerThread[];    private List<Runnable> listqueue = new LinkedList<Runnable>();    private static ThreadPool threadPool;    public ThreadPool(){        this(workThreadNum);//无参构造器    }    public ThreadPool(int workNum){     ThreadPool.workThreadNum = workNum;        workerThread = new WorkerThread[workThreadNum];        for(int i=0;i<workThreadNum;i++) {            workerThread[i] = new WorkerThread();            workerThread[i].start();        }    }    public static ThreadPool getThreadPool(){        return new ThreadPool(workThreadNum);    }    public static ThreadPool getThreadPool(int workThreadNum){        if(threadPool == null){            return new ThreadPool(workThreadNum);        }        return threadPool;    }    public void execute(Runnable runnable){        synchronized (listqueue){            listqueue.add(runnable);            listqueue.notify();        }    }    public void execute(Runnable runnable[]){        synchronized (listqueue) {            for (Runnable c : runnable) {                listqueue.add(c);                listqueue.notify();            }        }    }    public void execute(List<Runnable> runnables){        synchronized (listqueue){            for(int i = 0;i<runnables.size();i++) {                    listqueue.add(runnables.get(i));            }        }    }    public class WorkerThread extends Thread{        boolean isRunning = true;        Runnable runnable;        public void run(){            while (isRunning){                synchronized (listqueue) {                    if (isRunning && listqueue.isEmpty()) {                        try {                            listqueue.wait(50);                        } catch (InterruptedException e) {                            e.printStackTrace();                        }                    }                    if (!listqueue.isEmpty()) {                        runnable = listqueue.remove(0);                    }            }                if (runnable != null) {                    runnable.run();                }                FINISH_TASK++;                runnable = null;            }        }    }}

public class Test {    public static void main(String[] args){        ThreadPool threadPool = ThreadPool.getThreadPool(5);        threadPool.execute(new Runnable[]{new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task()});        threadPool.execute(new Runnable[]{new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task()});        threadPool.execute(new Runnable[]{new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task(),new Task()});    }}

0 0