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Java 创建线程池的四种方式
1、newCachedThreadPool 创建一个可缓存线程池,如果线程池长度超过处理需要,可灵活回收空闲线程,若无可回收,则新建线程。
2、newFixedThreadPool 创建一个定长线程池,可控制线程最大并发数,超出的线程会在队列中等待。
3、newScheduledThreadPool 创建一个定长线程池,支持定时及周期性任务执行。
4、newSingleThreadExecutor 创建一个单线程化的线程池,它只会用唯一的工作线程来执行任务,保证所有任务按照指定顺序(FIFO, LIFO, 优先级)执行。
newCachedThreadPool
创建一个可缓存线程池,如果线程池长度超过处理需要,可灵活回收空闲线程,
若无可回收,则新建线程。
package cn.qbz.thread; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class Test111907 { public static void main(String[] args) { ExecutorService executorService = Executors.newCachedThreadPool(); for (int i = 0; i < 10; i++) { final int temp = i; executorService.execute(new Runnable() { @Override public void run() { try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(Thread.currentThread().getName() + " i=" + temp); } }); } } } public static ExecutorService newCachedThreadPool() { return new ThreadPoolExecutor(0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>()); }
newFixedThreadPool
创建一个定长线程池,可控制线程最大并发数,超出的线程会在队列中等待。
package cn.qbz.thread; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class Test111907 { public static void main(String[] args) { ExecutorService executorService = Executors.newFixedThreadPool(3); for (int i = 0; i < 10; i++) { final int temp = i; executorService.execute(new Runnable() { @Override public void run() { try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(Thread.currentThread().getName() + " i=" + temp); } }); } } } public static ExecutorService newFixedThreadPool(int nThreads) { return new ThreadPoolExecutor(nThreads, nThreads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>()); }
newScheduledThreadPool
创建一个定长线程池,支持定时及周期性任务执行。
package cn.qbz.thread; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class Test111907 { public static void main(String[] args) { final long begin = System.currentTimeMillis(); ExecutorService executorService = Executors.newScheduledThreadPool(3); for (int i = 0; i < 10; i++) { final int temp = i; final long time = begin; executorService.schedule(new Runnable() { @Override public void run() { try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(Thread.currentThread().getName() + " i=" + temp + " time=" + (System.currentTimeMillis() - time)); } }, 5, TimeUnit.SECONDS); } } } public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) { return new ScheduledThreadPoolExecutor(corePoolSize); } public ScheduledThreadPoolExecutor(int corePoolSize) { super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, new DelayedWorkQueue()); }
newSingleThreadExecutor
创建一个单线程化的线程池,它只会用唯一的工作线程来执行任务,
保证所有任务按照指定顺序(FIFO, LIFO, 优先级)执行。
package cn.qbz.thread; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class Test111907 { public static void main(String[] args) { ExecutorService executorService = Executors.newSingleThreadExecutor(); for (int i = 0; i < 10; i++) { final int temp = i; executorService.execute(new Runnable() { @Override public void run() { try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(Thread.currentThread().getName() + " i=" + temp); } }); } } }
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