java - 如何取消已经安排好的TimerTask？

Question

我有一个小问题，我似乎无法正确处理。我在java中有以下类:

package pooledtcpconnector.utilities;

import java.io.IOException;
import java.io.InputStream;
import java.util.Timer;
import java.util.TimerTask;
import java.util.logging.Level;
import java.util.logging.Logger;

public final class Notifier implements Runnable {

    private final ILogger logger;

    private Timer mTimer;
    private final int Treshold;
    private final InputStream ResponseStream;
    private final TimerTask DoWaitTask;

    public Notifier(final InputStream _ResponseStream, final Integer _Treshold, final ILogger logger) {
        this.logger = logger;

        mTimer = new Timer();

        this.ResponseStream = _ResponseStream;
        this.Treshold = _Treshold;

        DoWaitTask = new TimerTask() {
            @Override
            public void run() {
                try {
                    int mSize = ResponseStream.available();
                    if (mSize >= Treshold) {
                        mTimer.cancel();
                    }
                } catch (final IOException ex) {
                    final String ExceptionMessage = ex.getMessage();
                    logger.LogMessage(
                            this.getClass().getCanonicalName(),
                            "Notifier.DoWaitTask:run.ResponseStream.available",
                            ex.getClass().getCanonicalName(),
                            new String[]{
                                ExceptionMessage,
                                "Parameters:",
                                String.format("-"),
                            });

                    Logger.getLogger(Notifier.class.getCanonicalName()).log(Level.FINE, ex.getMessage(), ex.getCause());
                }
            }
        };
    }

    @Override
    public void run() {
        synchronized (this) {
            mTimer.scheduleAtFixedRate(DoWaitTask, 250, 200);
            // Notification mechanism
            notify();
        }
    }

}

此类将确保我们的应用程序不会开始处理 SocketInputStream，除非可用方法至少返回 Treshold。然而问题是，一旦我用计时器安排 DoWaitTask，它就会永远运行。通过取消计时器，任务仍然运行并且整个应用程序挂起，但更重要的是，一旦流已经被处理并关闭，它就会尝试调用流上的 available 。当然，这会导致一个很好的 IOException:流已关闭。

如何将计划任务与计时器一起停止？ timer.cancel 显然是不够的。

问候， 乔伊

Answer 1

使用TimerTask.cancel()从计时器任务的 run() 方法中。根据此方法的 Javadoc:

Note that calling this method from within the run method of a repeating timer task absolutely guarantees that the timer task will not run again.