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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。示例代码如下：
1 package test; 2 import java.util.concurrent.ExecutorService; 3 import java.util.concurrent.Executors; 4 public class ThreadPoolExecutorTest { 5 public static void main(String[] args) { 6 ExecutorService cachedThreadPool = Executors.newCachedThreadPool(); 7 for (int i = 0; i < 10; i++) { 8 final int index = i; 9 try { 10 Thread.sleep(index * 1000); 11 } catch (InterruptedException e) { 12 e.printStackTrace(); 13 } 14 cachedThreadPool.execute(new Runnable() { 15 public void run() { 16 System.out.println(index); 17 } 18 }); 19 } 20 } 21 }
线程池为无限大，当执行第二个任务时第一个任务已经完成，会复用执行第一个任务的线程，而不用每次新建线程。
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。示例代码如下：
1 package test; 2 import java.util.concurrent.ExecutorService; 3 import java.util.concurrent.Executors; 4 public class ThreadPoolExecutorTest { 5 public static void main(String[] args) { 6 ExecutorService fixedThreadPool = Executors.newFixedThreadPool(3); 7 for (int i = 0; i < 10; i++) { 8 final int index = i; 9 fixedThreadPool.execute(new Runnable() { 10 public void run() { 11 try { 12 System.out.println(index); 13 Thread.sleep(2000); 14 } catch (InterruptedException e) { 15 e.printStackTrace(); 16 } 17 } 18 }); 19 } 20 } 21 }
因为线程池大小为3，每个任务输出index后sleep 2秒，所以每两秒打印3个数字。
定长线程池的大小最好根据系统资源进行设置。如Runtime.getRuntime().availableProcessors()
创建一个定长线程池，支持定时及周期性任务执行。延迟执行示例代码如下：
1 package test; 2 import java.util.concurrent.Executors; 3 import java.util.concurrent.ScheduledExecutorService; 4 import java.util.concurrent.TimeUnit; 5 public class ThreadPoolExecutorTest { 6 public static void main(String[] args) { 7 ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5); 8 scheduledThreadPool.schedule(new Runnable() { 9 public void run() { 10 System.out.println("delay 3 seconds"); 11 } 12 }, 3, TimeUnit.SECONDS); 13 } 14 }
表示延迟3秒执行。
定期执行示例代码如下：
1 package test; 2 import java.util.concurrent.Executors; 3 import java.util.concurrent.ScheduledExecutorService; 4 import java.util.concurrent.TimeUnit; 5 public class ThreadPoolExecutorTest { 6 public static void main(String[] args) { 7 ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5); 8 scheduledThreadPool.scheduleAtFixedRate(new Runnable() { 9 public void run() { 10 System.out.println("delay 1 seconds, and excute every 3 seconds"); 11 } 12 }, 1, 3, TimeUnit.SECONDS); 13 } 14 }
表示延迟1秒后每3秒执行一次。
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。示例代码如下：
1 package test; 2 import java.util.concurrent.ExecutorService; 3 import java.util.concurrent.Executors; 4 public class ThreadPoolExecutorTest { 5 public static void main(String[] args) { 6 ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor(); 7 for (int i = 0; i < 10; i++) { 8 final int index = i; 9 singleThreadExecutor.execute(new Runnable() { 10 public void run() { 11 try { 12 System.out.println(index); 13 Thread.sleep(2000); 14 } catch (InterruptedException e) { 15 e.printStackTrace(); 16 } 17 } 18 }); 19 } 20 } 21 }
结果依次输出，相当于顺序执行各个任务。
http://cuisuqiang.iteye.com/blog/2019372
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原文地址：http://www.cnblogs.com/nathan909/p/5411327.html
