如何在Java中安全地停止和恢复线程？

public class StoppableThread extends Thread {
    private volatile boolean stopRequested = false;

    public void requestStop() {
        stopRequested = true;
    }

    @Override
    public void run() {
        while (!stopRequested) {
            // 执行任务
        }
    }
}

public class PausableThread extends Thread {
    private volatile boolean paused = false;

    public void pause() {
        paused = true;
    }

    public void resume() {
        paused = false;
    }

    @Override
    public void run() {
        while (!paused) {
            // 执行任务
        }
    }
}