在Java中，是否可以在一段时间内执行方法并在达到时间限制后停止? [英] In Java, is it possible to execute a method for a period of time and stop after it reaches the time limit?

问题描述

我有下面的代码可以下载网页:

I have this code that downloads a web page:

HttpURLConnection connection;

private String downloadContent() {
    InputStream content;
    Source parser;
    try {
        content = connection.getInputStream(); //<--here is the download
        parser = new Source(content);            
        content.close();
        return parser.toString();
    } catch (Exception e) {
        return null;
    }
}

在进行下载时，我尝试获取已下载数据的数量，如果达到限制，我将停止下载，但是我没有找到执行此操作的方法.如果有人知道该怎么做，请告诉我.

While doing the download, I tried to get the amount of downloaded data, and if it reaches a limit, I stop the downloading, but I not found a way to do this. If someone know how to do, please tell me.

现在，我想限制下载时间.示例:如果下载通过20秒，我将停止它.我要这样做是因为我的程序是一个网络爬虫，如果出现错误，它将开始下载一个大文件，它将卡在下载文件中，而不是我不想这样做，因此欢迎按大小过滤下载，但我不知道，过滤时间可以避免此问题.

Now I want to limit the download time. Example: if the download pass 20 seconds, I stop it. I want to do this because my program it's an webcrawler and if by an error, it begins downloading a big file, it will stuck in the download, and is not this I want to do, so a filter in download by size is welcome, but as I don't know, a filter time will prevent this problem.

推荐答案

实现此目标的正确方法如下:

The proper way to achieve this is the following:

public class TimeOut {

    public static class MyJob implements Callable<String> {

        @Override
        public String call() throws Exception {
            // Do something
            return "result";
        }

    }

    public static void main(String[] args) {

        Future<String> control
                = Executors.newSingleThreadExecutor().submit(new MyJob());

        try {

            String result = control.get(5, TimeUnit.SECONDS);

        } catch (TimeoutException ex) {

            // 5 seconds expired, we cancel the job !!!
            control.cancel(true);

        }
        catch (InterruptedException ex) {

        } catch (ExecutionException ex) {

        }

    }

}

这篇关于在Java中，是否可以在一段时间内执行方法并在达到时间限制后停止?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！