执行程序如何在java中终止递归？ [英] How is an executor termination recursion in java?

问题描述

这是一个程序，它读取以前格式的信息站点，它使用递归和执行器。工作正常，我的问题是测试程序是否完成和成功通知。

This is a program that reads information site for previous format it uses recursion and executor.It works fine,my problem is to test whether the program is completed and success notification.

public class NewClass { 

    static String levels[] = { "div.col-md-9 li a", "div#sidebar ul li a" };    
    static String links = "";   

    private void getRecursive(String href, int level, final ExecutorService executor) { 

        if (level > levels.length - 1) {    
            return; 
        }   

        Document doc;   
        try {   
            doc = Jsoup.connect(href).get();    
            Elements elements = doc.select(levels[level]);  
            final int flevel = ++level; 
            for (final Element element : elements) {    
                executor.execute(new Runnable() {   
                    @Override   
                    public void run() { 
                        if (!element.attr("href").isEmpty()) {  
                            links += element.attr("abs:href") + "\n";   
                            System.out.println(links);  
                            getRecursive(element.attr("abs:href"), flevel, executor);   
                        }   
                    }   
                }); 
            }   
        } catch (IOException e1) {  
            e1.printStackTrace();   
        }   
    }   

如果 levels.length = 1 ，规则执行器运行良好，但如果 levels.length> 1 将出现错误：线程pool-1-thread-138中的异常java.util.concurrent.RejectedExecutionException

If levels.length = 1, the rule enforcer works well,but If levels.length>1 will appear error : Exception in thread "pool-1-thread-138" java.util.concurrent.RejectedExecutionException

    public static void main(String[] args) {    
    try {
        ExecutorService executor = Executors.newFixedThreadPool(5);
        new NewClass().getRecursive("http://www.java2s.com/", 0, executor);
        executor.shutdown();
        executor.awaitTermination(1, TimeUnit.HOURS);
        if (executor.isTerminated()) {
            JOptionPane.showMessageDialog(null, "Success");
        }
    } catch (Exception ex) {
        Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null, ex);
    }
}   
}

推荐答案

关闭 ExecutorService 后，您无法提交任何新任务，在您处理完所有级别后，递归似乎停止了（您不提交之后的任何新任务，你可以这样做：

You can't submit any new tasks after you shutdown the ExecutorService, the recursion seems to stop after you've processed all the levels (you don't submit any new tasks after that), you can do something like this:

if (level > levels.length - 1) {    
    executor.shutdown();
    return; 
}   

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