一種實現“通信層”的方案，主要演示超時控制

/**
 * 一種實現“通信層”的方案，主要演示超時控制
 * 
 * 2012-12-26 according the Thinking in Java
 */

package concurrent;

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;


class TaskWithResult implements Callable<String> {
    private int id;

    TaskWithResult() {
        this.id = ++count;
    }

    private static int count = -1;

    @Override
    public String call() throws Exception {
        long timeout = System.currentTimeMillis() + 1000 * count;
        while (System.currentTimeMillis() < timeout)
            ;
        return "result of TaskWithResult " + id;
    }

}

public class CallableDemo {
    public static void main(String[] args) {
        ExecutorService exec = Executors.newCachedThreadPool();
        ArrayList<Future<String>> results = new ArrayList<Future<String>>();
        for (int i = 0; i < 10; i++) {
            results.add(exec.submit(new TaskWithResult()));
        }

        for (Future<String> fs : results) {
            try {
                // get() blocks util completion:
                System.out.println(fs.get(1, TimeUnit.SECONDS));
            } catch (InterruptedException e) {
                e.printStackTrace();
                return;
            } catch (ExecutionException e) {
                e.printStackTrace();
                return;
            } catch (TimeoutException e) {
                System.out.println("TimeoutException");
            } finally {
                exec.shutdown();
            }
        }
    }
}

/**
 * output(sample):
 * 
 * <pre>
 * result of TaskWithResult 0
 * result of TaskWithResult 1
 * result of TaskWithResult 2
 * result of TaskWithResult 3
 * result of TaskWithResult 4
 * TimeoutException
 * result of TaskWithResult 6
 * result of TaskWithResult 7
 * TimeoutException
 * TimeoutException
 * </pre>
 */