eclipse tomcat 网站开发,建站宝盒怎么样,360元网站建设,百度引擎搜索网址http://cuisuqiang.iteye.com/blog/2019372 Java通过Executors提供四种线程池#xff0c;分别为#xff1a;newCachedThreadPool创建一个可缓存线程池#xff0c;如果线程池长度超过处理需要#xff0c;可灵活回收空闲线程#xff0c;若无可回收#xff0c;则新建线程。n…http://cuisuqiang.iteye.com/blog/2019372 Java通过Executors提供四种线程池分别为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。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。newScheduledThreadPool 创建一个定长线程池支持定时及周期性任务执行。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。 (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。示例代码如下 Java代码 package test; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class ThreadPoolExecutorTest { public static void main(String[] args) { ExecutorService cachedThreadPool Executors.newCachedThreadPool(); for (int i 0; i 10; i) { final int index i; try { Thread.sleep(index * 1000); } catch (InterruptedException e) { e.printStackTrace(); } cachedThreadPool.execute(new Runnable() { public void run() { System.out.println(index); } }); } } } 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。 (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。示例代码如下 Java代码 package test; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class ThreadPoolExecutorTest { public static void main(String[] args) { ExecutorService fixedThreadPool Executors.newFixedThreadPool(3); for (int i 0; i 10; i) { final int index i; fixedThreadPool.execute(new Runnable() { public void run() { try { System.out.println(index); Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); } } }); } } } 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() (3) newScheduledThreadPool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 Java代码 package test; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class ThreadPoolExecutorTest { public static void main(String[] args) { ScheduledExecutorService scheduledThreadPool Executors.newScheduledThreadPool(5); scheduledThreadPool.schedule(new Runnable() { public void run() { System.out.println(delay 3 seconds); } }, 3, TimeUnit.SECONDS); } } 表示延迟3秒执行。 定期执行示例代码如下 Java代码 package test; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class ThreadPoolExecutorTest { public static void main(String[] args) { ScheduledExecutorService scheduledThreadPool Executors.newScheduledThreadPool(5); scheduledThreadPool.scheduleAtFixedRate(new Runnable() { public void run() { System.out.println(delay 1 seconds, and excute every 3 seconds); } }, 1, 3, TimeUnit.SECONDS); } } 表示延迟1秒后每3秒执行一次。 (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。示例代码如下 Java代码 package test; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class ThreadPoolExecutorTest { public static void main(String[] args) { ExecutorService singleThreadExecutor Executors.newSingleThreadExecutor(); for (int i 0; i 10; i) { final int index i; singleThreadExecutor.execute(new Runnable() { public void run() { try { System.out.println(index); Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); } } }); } } } 结果依次输出相当于顺序执行各个任务。 你可以使用JDK自带的监控工具来监控我们创建的线程数量运行一个不终止的线程创建指定量的线程来观察工具目录C:\Program Files\Java\jdk1.6.0_06\bin\jconsole.exe运行程序做稍微修改 Java代码 package test; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class ThreadPoolExecutorTest { public static void main(String[] args) { ExecutorService singleThreadExecutor Executors.newCachedThreadPool(); for (int i 0; i 100; i) { final int index i; singleThreadExecutor.execute(new Runnable() { public void run() { try { while(true) { System.out.println(index); Thread.sleep(10 * 1000); } } catch (InterruptedException e) { e.printStackTrace(); } } }); try { Thread.sleep(500); } catch (InterruptedException e) { e.printStackTrace(); } } } } 效果如下 选择我们运行的程序 监控运行状态转载于:https://www.cnblogs.com/bill89/p/10483022.html
