Java Swing和线程计划

Question

I am trying to come up with a concept where in the GUI I can give a query and specify the Pacing and duration.Like I give it 2 mins and 5hrs..which translates like for every 2mins run the given query for the next 5hrs..Though my GUI is ready and able to submit a query...I am unable to bring in the above specified time concept..Though I am sure this can be done through threading...I am finding it difficult to code it...can anyone over here help me with a basic approach to solve this issue ? is there a better and easy approach than threading ? please help..

Answer 1

Taking your example, if you have a query that you want to run every 2 minutes for 5 hours, what you need to do is calculate the number of times you want the query to execute.

2 minutes = 120 seconds.
5 hours = 18,000 seconds.

Number of times (iterations) = 18,000 / 120 = 150 iterations.

Therefore, you would need to submit the query 150 times, every 120 seconds (or 120,000 milliseconds).

You have to use threads if you want to submit more than one query with your GUI.

Edited to add: Based on assylias's comment, here's some code

public void runQuery(int interval, int duration) {
    final Runnable query = new Runnable() {
        @Override
        public void run() {
            // Run query
        }
    };
    ScheduledExecutorService scheduler = Executors
            .newScheduledThreadPool(1);
    final ScheduledFuture<?> queryHandle = scheduler.scheduleAtFixedRate(
            query, 0, interval, TimeUnit.SECONDS);
    scheduler.schedule(new Runnable() {
        @Override
        public void run() {
            queryHandle.cancel(true);
        }
    }, duration, TimeUnit.SECONDS);
}

Just using Thread, here's another version.

public void runQuery(int interval, int duration) {
    final Runnable query = new Runnable() {
        @Override
        public void run() {
            // Run query
        }
    };
    int iterations = duration / interval;
    for (int i = 0; i < iterations; i++) {
        new Thread(query).start();
        for (int j = 0; j < interval; j++) {
            try {
                Thread.sleep(1000L);
            } catch (InterruptedException e) {
            }
        }
    }
}

The Runnable query is just a place holder in these code examples.

You going to have to write a class that implements Runnable and passes the results of your query back to the GUI. Since you're not on the Swing Event Dispatch thread, you'll have to use the SwingUtilities.invokeLater() method to actually make GUI changes.

You would pass an instance of your class to one of these threaded methods to be executed for the interval and duration that you pass.