java简单实现多线程及线程池实例详解

本文为大家分享了java多线程的简单实现及线程池实例，供大家参考，具体内容如下

一、多线程的两种实现方式

1、继承Thread类的多线程

/**
 * 继承Thread类的多线程简单实现
 */
public class extThread extends Thread { 

   public void run(){
      for(int i=0;i<100;i++){
        System.out.println(getName()+"-"+i);
      }
   } 

   public static void main(String arg[]){
      for(int i=0;i<100;i++){
        System.out.println(Thread.currentThread().getName()+"-"+i);
        if(i==50){
           new extThread().start();
           new extThread().start();
        }
      }
   }
} 

2、实现Runnable接口的多线程

/**
 * 实现runable接口的多线程实例
 */
public class runThread implements Runnable {
   public void run(){
      for(int i=0;i<100;i++){
        System.out.println(Thread.currentThread().getName()+"-"+i);
      }
   } 

   public static void main(String arg[]){
      for(int i=0;i<100;i++){
        System.out.println(Thread.currentThread().getName()+"-"+i);
        if(i==50){
           runThread rt = new runThread();
           new Thread(rt,"新线程1").start();
           new Thread(rt,"新线程2").start();
        }
      }
   } 

} 

二、线程池的简单实现

//实现Runnable接口
class TestThread implements Runnable{ 

  public void run() {
    for(int i = 0;i < 100;i++){
      System.out.println(Thread.currentThread().getName() + "i的值为：" + i);
    }
  }
} 

public class threadPoolTest { 

  public static void main(String[] args) {
    //创建一个具有固定线程数的线程池
    ExecutorService pool = Executors.newFixedThreadPool(5);
    //向线程池中提交三个线程
    pool.submit(new TestThread());
    pool.submit(new TestThread());
    pool.submit(new TestThread());
    //关闭线程池
    pool.shutdown();
  } 

}

三、java爬虫使用线程池实例

/**
 * 爬虫调度线程池
 */
public class threadPool { 

  public static HashMap<String, Spiders> statusMap = new HashMap<String, Spiders>();
  // 存放爬虫，key为爬虫的id，value为爬虫的线程池
  static HashMap<Integer, ThreadPoolExecutor> threadMap = new HashMap<Integer, ThreadPoolExecutor>();
  //创建一个线程池
  static ThreadPoolExecutor threadPool = new ThreadPoolExecutor(200, 230,80000L,
      TimeUnit.SECONDS,
      new ArrayBlockingQueue<Runnable>(10),
      new ThreadPoolExecutor.CallerRunsPolicy()); 

  public static void executeThread(Spiders spider) {
    statusMap.put(String.valueOf(spider.getId()), spider);
    // 爬虫有效
    if (spider.getFlag() == 0) {
      if (spider.getStatus() == 0) {
        // 表示爬虫进入抓取状态
        ThreadPoolExecutor detailPool = null;
        if (threadMap.get(spider.getId()) == null) {
          detailPool = new ThreadPoolExecutor(30, 80, 80000L,
              TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(
                  10),
              new ThreadPoolExecutor.CallerRunsPolicy());
          threadMap.put(spider.getId(), detailPool);
          threadPool.execute(new threadRun(spider, threadMap));
        }
      }
    }
  }
} 

//实现Runnable接口
class threadRun implements Runnable { 

  private HashMap<Integer, ThreadPoolExecutor> threadPoolMap;
  private Spiders spider; 

  public threadRun(Spiders spider,
      HashMap<Integer, ThreadPoolExecutor> threadPoolMap) {
    this.threadPoolMap = threadPoolMap;
    this.spider = spider;
  } 

  //线程执行体
  public void run() {
    try {
      if ("rong360".equals(spider.getWebsite())) {
        new RongThread(threadPoolMap.get(spider.getId()), spider)
            .startSpider();
      } else if ("xxgg_sd".equals(spider.getWebsite())) {
        new Spider_ShanDong(threadPoolMap.get(spider
            .getId()), spider).startSpider();
      } else if ("xxgg_gz".equals(spider.getWebsite())) {
        new Spider_GuiZhou(threadPoolMap.get(spider
            .getId()), spider).startSpider();
      } else if ("sx".equals(spider.getWebsite())) {
        new SpiderSX(spider).startSpider();
      } else if ("baidu".equals(spider.getWebsite())) {
        new SpiderBaiDu(spider).startSpider();
      } else if ("11315".equals(spider.getWebsite())) {
        new Spider11315ByName(spider).startSpider();
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  } 

}

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