下面通过实例代码为大家介绍Java线程池的几种实现方法和区别:
网站设计、网站建设介绍好的网站是理念、设计和技术的结合。成都创新互联公司拥有的网站设计理念、多方位的设计风格、经验丰富的设计团队。提供PC端+手机端网站建设,用营销思维进行网站设计、采用先进技术开源代码、注重用户体验与SEO基础,将技术与创意整合到网站之中,以契合客户的方式做到创意性的视觉化效果。import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.List; import java.util.Random; import java.util.concurrent.Callable; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future; public class TestThreadPool { // -newFixedThreadPool与cacheThreadPool差不多,也是能reuse就用,但不能随时建新的线程 // -其独特之处:任意时间点,最多只能有固定数目的活动线程存在,此时如果有新的线程要建立,只能放在另外的队列中等待,直到当前的线程中某个线程终止直接被移出池子 // -和cacheThreadPool不同,FixedThreadPool没有IDLE机制(可能也有,但既然文档没提,肯定非常长,类似依赖上层的TCP或UDP // IDLE机制之类的),所以FixedThreadPool多数针对一些很稳定很固定的正规并发线程,多用于服务器 // -从方法的源代码看,cache池和fixed 池调用的是同一个底层池,只不过参数不同: // fixed池线程数固定,并且是0秒IDLE(无IDLE) // cache池线程数支持0-Integer.MAX_VALUE(显然完全没考虑主机的资源承受能力),60秒IDLE private static ExecutorService fixedService = Executors.newFixedThreadPool(6); // -缓存型池子,先查看池中有没有以前建立的线程,如果有,就reuse.如果没有,就建一个新的线程加入池中 // -缓存型池子通常用于执行一些生存期很短的异步型任务 // 因此在一些面向连接的daemon型SERVER中用得不多。 // -能reuse的线程,必须是timeout IDLE内的池中线程,缺省timeout是60s,超过这个IDLE时长,线程实例将被终止及移出池。 // 注意,放入CachedThreadPool的线程不必担心其结束,超过TIMEOUT不活动,其会自动被终止。 private static ExecutorService cacheService = Executors.newCachedThreadPool(); // -单例线程,任意时间池中只能有一个线程 // -用的是和cache池和fixed池相同的底层池,但线程数目是1-1,0秒IDLE(无IDLE) private static ExecutorService singleService = Executors.newSingleThreadExecutor(); // -调度型线程池 // -这个池子里的线程可以按schedule依次delay执行,或周期执行 private static ExecutorService scheduledService = Executors.newScheduledThreadPool(10); public static void main(String[] args) { DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); ListcustomerList = new ArrayList (); System.out.println(format.format(new Date())); testFixedThreadPool(fixedService, customerList); System.out.println("--------------------------"); testFixedThreadPool(fixedService, customerList); fixedService.shutdown(); System.out.println(fixedService.isShutdown()); System.out.println("----------------------------------------------------"); testCacheThreadPool(cacheService, customerList); System.out.println("----------------------------------------------------"); testCacheThreadPool(cacheService, customerList); cacheService.shutdownNow(); System.out.println("----------------------------------------------------"); testSingleServiceThreadPool(singleService, customerList); testSingleServiceThreadPool(singleService, customerList); singleService.shutdown(); System.out.println("----------------------------------------------------"); testScheduledServiceThreadPool(scheduledService, customerList); testScheduledServiceThreadPool(scheduledService, customerList); scheduledService.shutdown(); } public static void testScheduledServiceThreadPool(ExecutorService service, List customerList) { List > listCallable = new ArrayList >(); for (int i = 0; i < 10; i++) { Callable callable = new Callable () { @Override public Integer call() throws Exception { return new Random().nextInt(10); } }; listCallable.add(callable); } try { List > listFuture = service.invokeAll(listCallable); for (Future future : listFuture) { Integer id = future.get(); customerList.add(id); } } catch (Exception e) { e.printStackTrace(); } System.out.println(customerList.toString()); } public static void testSingleServiceThreadPool(ExecutorService service, List customerList) { List >> listCallable = new ArrayList >>(); for (int i = 0; i < 10; i++) { Callable > callable = new Callable
>() { @Override public List
call() throws Exception { List list = getList(new Random().nextInt(10)); boolean isStop = false; while (list.size() > 0 && !isStop) { System.out.println(Thread.currentThread().getId() + " -- sleep:1000"); isStop = true; } return list; } }; listCallable.add(callable); } try { List >> listFuture = service.invokeAll(listCallable); for (Future > future : listFuture) { List
list = future.get(); customerList.addAll(list); } } catch (Exception e) { e.printStackTrace(); } System.out.println(customerList.toString()); } public static void testCacheThreadPool(ExecutorService service, List customerList) { List >> listCallable = new ArrayList >>(); for (int i = 0; i < 10; i++) { Callable > callable = new Callable
>() { @Override public List
call() throws Exception { List list = getList(new Random().nextInt(10)); boolean isStop = false; while (list.size() > 0 && !isStop) { System.out.println(Thread.currentThread().getId() + " -- sleep:1000"); isStop = true; } return list; } }; listCallable.add(callable); } try { List >> listFuture = service.invokeAll(listCallable); for (Future > future : listFuture) { List
list = future.get(); customerList.addAll(list); } } catch (Exception e) { e.printStackTrace(); } System.out.println(customerList.toString()); } public static void testFixedThreadPool(ExecutorService service, List customerList) { List >> listCallable = new ArrayList >>(); for (int i = 0; i < 10; i++) { Callable > callable = new Callable
>() { @Override public List
call() throws Exception { List list = getList(new Random().nextInt(10)); boolean isStop = false; while (list.size() > 0 && !isStop) { System.out.println(Thread.currentThread().getId() + " -- sleep:1000"); isStop = true; } return list; } }; listCallable.add(callable); } try { List >> listFuture = service.invokeAll(listCallable); for (Future > future : listFuture) { List
list = future.get(); customerList.addAll(list); } } catch (Exception e) { e.printStackTrace(); } System.out.println(customerList.toString()); } public static List getList(int x) { List list = new ArrayList (); list.add(x); list.add(x * x); return list; } }