复杂线程控制

Question

假设我有3个执行线程，下面描述每个线程将做什么

螺纹1-主螺纹螺纹2-检测器螺纹线程3-动作线程

当线程1启动时，它将生成线程2。线程2将简单地与线程1一起运行并搜索事件。当事件发生时，我希望线程2生成一个新线程，即线程3。我希望线程3与线程1连接。这可能吗？

样本代码：

 public class ThreadA {
// variable to flag if ThreadB should still loop
private static boolean runThreadB = true;
public void mainMethod() {
    new ThreadB().start();
    // do some stuff
    // make sure thread B can end
    runThreadB = false;
}
// inner class / Thread B
class ThreadB extends Thread {
    @Override
    public void run() {
        // loop until Thread A is done
        while (runThreadB) {
            // wait for event, if event is found, spawn thread C
            ThreadC threadC = new ThreadC();
            threadC.start();
            /**
             * Need thread C to somehow join ThreadA
             */
            try {
                threadC.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

}

 public class ThreadC extends Thread {
@Override
public void run() {
    // perform some tasks
}

}

Answer 1

必须同步线程。您可以使用ReentrantLock来执行此操作。

以下是您的问题（事件生产者-消费者）的一个简单示例：

public class Foo{
    //...
    public void consumeEvent() throws InterruptedException{
        aLock.lock();
        try {
            while(noEvent){
                eventAvailable.await();
            }
            // use the event
        } finally {
            sLock.unlock();
        }
    }
    public void createEvent() throws InterruptedException{
        aLock.lock();
        try {
            // add an event
            eventAvailable.signalAll();
        } finally {
            sLock.unlock();
        }
    }
    private Lock aLock = new ReentrantLock();
    private Condition eventAvailable = aLock.newCondition();
}

您的线程将使用此类中的一个对象。

Thread eventProducer = ...
Thread eventConsumer = ...
eventProducer.start();
eventConsumer.start();

您的线程现在已同步。