package com.trip.platform.task;

import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import javax.annotation.PostConstruct;

import org.springframework.stereotype.Component;

/**
 * Task执行者.
 * 
 */
@Component
public class TaskExecutor {

    /**
     * 线程池（最大100，队列满了重新执行）.
     */
    private ExecutorService executor = new ThreadPoolExecutor(2, 100,
            60L, TimeUnit.SECONDS,
            new SynchronousQueue<Runnable>(),new ThreadPoolExecutor.CallerRunsPolicy());


    /**
     * 自动执行
     */
    @PostConstruct
    public void execute() {

        Thread t = new pollThread();
        t.setDaemon(true);
        t.setName("TaskExecutor");
        t.start();
    }

    /**
     * 执行线程.
     * 
     */
    class pollThread extends Thread {
        public void run() {
            while (true) {

                // 从每个IPCC的子队列取出一个task，放入线程池
                List<QueueTask> list = MultiQueueTaskCenter.pollTask();
                for (QueueTask task : list) {
                    executor.execute(task);
                }

                // 休眠指定的时间
                try {
                    Thread.sleep(10); //1秒取100次任务
                } catch (InterruptedException e) {
                }
            }
        }
    }
}

Exception in thread "TaskExecutor" java.lang.NullPointerException
        at com.trip.xxx.xxx.controller.xxxController$1.run(xxxController.java:543)
        at java.util.concurrent.ThreadPoolExecutor$CallerRunsPolicy.rejectedExecution(ThreadPoolExecutor.java:2038)
        at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
        at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
        at com.trip.platform.task.TaskExecutor$pollThread.run(TaskExecutor.java:51)

public static class CallerRunsPolicy implements RejectedExecutionHandler {
        /**
         * Creates a {@code CallerRunsPolicy}.
         */
        public CallerRunsPolicy() { }

        /**
         * Executes task r in the caller's thread, unless the executor
         * has been shut down, in which case the task is discarded.
         *
         * @param r the runnable task requested to be executed
         * @param e the executor attempting to execute this task
         */
        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
            if (!e.isShutdown()) {
                r.run();
            }
        }
    }