Java7并发编程实战（一） 守护线程的创建和运行

package com.packtpub.java7.concurrency.chapter1.recipe7.event;

import java.util.Date;

/**
 * Class that stores event‘s information 
 *
 */
public class Event {

    /**
     * Date of the event
     */
    private Date date;
    
    /**
     * Message of the event
     */
    private String event;
    
    /**
     * Reads the Date of the event
     * @return the Date of the event
     */
    public Date getDate() {
        return date;
    }
    
    /**
     * Writes the Date of the event
     * @param date the date of the event
     */
    public void setDate(Date date) {
        this.date = date;
    }
    
    /**
     * Reads the message of the event
     * @return the message of the event
     */
    public String getEvent() {
        return event;
    }
    
    /**
     * Writes the message of the event
     * @param event the message of the event
     */
    public void setEvent(String event) {
        this.event = event;
    }
}

package com.packtpub.java7.concurrency.chapter1.recipe7.task;

import java.util.Date;
import java.util.Deque;
import java.util.concurrent.TimeUnit;

import com.packtpub.java7.concurrency.chapter1.recipe7.event.Event;

/**
 * Runnable class that generates and event every second
 *
 */
public class WriterTask implements Runnable {

    /**
     * Data structure to stores the events
     */
    Deque<Event> deque;
    
    /**
     * Constructor of the class
     * @param deque data structure that stores the event
     */
    public WriterTask (Deque<Event> deque){
        this.deque=deque;
    }
    
    /**
     * Main class of the Runnable
     */
    @Override
    public void run() {
        
        // Writes 100 events
        for (int i=1; i<100; i++) {
            // Creates and initializes the Event objects 
            Event event=new Event();
            event.setDate(new Date());
            event.setEvent(String.format("The thread %s has generated an event",Thread.currentThread().getId()));
            
            // Add to the data structure
            deque.addFirst(event);
            try {
                // Sleeps during one second
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

package com.packtpub.java7.concurrency.chapter1.recipe7.task;

import java.util.Date;
import java.util.Deque;

import com.packtpub.java7.concurrency.chapter1.recipe7.event.Event;

/**
 * Class that review the Event data structure and delete
 * the events older than ten seconds
 *
 */
public class CleanerTask extends Thread {

    /**
     * Data structure that stores events
     */
    private Deque<Event> deque;

    /**
     * Constructor of the class
     * @param deque data structure that stores events
     */
    public CleanerTask(Deque<Event> deque) {
        this.deque = deque;
        // Establish that this is a Daemon Thread
        setDaemon(true);
    }


    /**
     * Main method of the class
     */
    @Override
    public void run() {
        while (true) {
            Date date = new Date();
            clean(date);
        }
    }

    /**
     * Method that review the Events data structure and delete
     * the events older than ten seconds
     * @param date
     */
    private void clean(Date date) {
        long difference;
        boolean delete;
        
        if (deque.size()==0) {
            return;
        }
        
        delete=false;
        do {
            Event e = deque.getLast();
            difference = date.getTime() - e.getDate().getTime();
            if (difference > 10000) {
                System.out.printf("Cleaner: %s\n",e.getEvent());
                deque.removeLast();
                delete=true;
            }    
        } while (difference > 10000);
        if (delete){
            System.out.printf("Cleaner: Size of the queue: %d\n",deque.size());
        }
    }
}