Detailed explanation of Java simple implementation of multi-threading and thread pool examples

This article shares the simple implementation of Java multithreading and thread pool examples for your reference. The specific content is as follows

1. Two implementation methods of multithreading

1. Multi-threading inherits Thread class

 /** * Simple implementation of multi-threading inheritance of Thread class*/ 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. Implementing multi-threading of Runnable interface

 /** * Multithreading instances that implement runable interface*/ 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,"New Thread1").start(); new Thread(rt,"New Thread2").start(); } } } }

2. Simple implementation of thread pool

 //Implement the Runnable interface class TestThread implements Runnable{ public void run() { for(int i = 0;i < 100;i++){ System.out.println(Thread.currentThread().getName() + "i is: " + i); } } } public class threadPoolTest { public static void main(String[] args) { //Create a thread pool with a fixed number of threads ExecutorService pool = Executors.newFixedThreadPool(5); //Submit three threads to the thread pool pool.submit(new TestThread()); pool.submit(new TestThread()); pool.submit(new TestThread()); //Close the thread pool pool.shutdown(); } }

3. Java crawlers use thread pool instances

 /** * Crawler dispatch thread pool*/ public class threadPool { public static HashMap<String, Spiders> statusMap = new HashMap<String, Spiders>(); // Store crawlers, key is the id of crawlers, value is the thread pool of crawlers static HashMap<Integer, ThreadPoolExecutor> threadMap = new HashMap<Integer, ThreadPoolExecutor>(); //Create a thread pool 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); // The crawler is valid if (spider.getFlag() == 0) { if (spider.getStatus() == 0) { // Indicates that the crawler enters the crawling state 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)); } } } } } //Implement the Runnable interface class threadRun implementations Runnable { private HashMap<Integer, ThreadPoolExecutor> threadPoolMap; private Spiders spider; public threadRun(Spiders spider, HashMap<Integer, ThreadPoolExecutor> threadPoolMap) { this.threadPoolMap = threadPoolMap; this.spider = spider; } //ThreadExecution body 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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