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();
   }
 }

}

来源：https://blog.csdn.net/William_hangshao/article/details/67644335