java线程池学习

     通常使用 Executor（执行器） 而不是显式地创建Thread对象。ExecutorService会自动切换上下文执行线程任务。

    1.CachedThreadPool:缓存线程池，会重复利用线程，线程不够会新建。

public class ExecutorCachedThreadPool {    public static void main(String[] args)    {        ExecutorService executorService = Executors.newCachedThreadPool();        for(int i =0 ; i< 10 ; i++)        {            executorService.execute(new Runnable() {                public void run() {                    System.out.println(Thread.currentThread().getName());                }            });        }        //启动一次顺序关闭，执行以前提交的任务，但不接受新任务。        executorService.shutdown();        //如果此执行程序已关闭，则返回 true。        boolean isShutdown = executorService.isShutdown();        //如果关闭后所有任务都已完成，则返回 true。        boolean isTerminated = executorService.isTerminated();        while(!executorService.isTerminated())        {            Thread.yield();        }        System.out.println("main end!");    }}执行结果：pool-1-thread-2pool-1-thread-2pool-1-thread-2pool-1-thread-6pool-1-thread-4pool-1-thread-3pool-1-thread-8pool-1-thread-1pool-1-thread-5pool-1-thread-7main end!    2.FixedThreadPool:固定数量线程池，在创建时需要预先分配线程的数量，与CachedThreadPool的区别就是限制了线程的数量。
public class ExecutorFixedThreadPool {    public static void main(String[] args)    {        ExecutorService executorService = Executors.newFixedThreadPool(5);        for(int i = 0 ; i < 8 ; i ++)        {            executorService.execute(new Runnable() {                public void run() {                    System.out.println(Thread.currentThread().getName());                }            });        }        executorService.shutdown();        while(!executorService.isTerminated())        {            Thread.yield();        }        System.out.println("main end");    }}
执行结果：

pool-1-thread-2
pool-1-thread-3
pool-1-thread-4
pool-1-thread-2
pool-1-thread-2
pool-1-thread-2
pool-1-thread-1
pool-1-thread-5
main end

    3.SingleThreadPool:单线程池，一个线程执行任务，按照创建任务的顺序依次执行。

public class ExecutorSingleThread {    public static void main(String[] args)    {        ExecutorService executorService = Executors.newSingleThreadExecutor();        for(int i =0 ; i< 5 ; i++)        {            executorService.execute(new Runnable() {                public void run() {                    System.out.println(Thread.currentThread().getName());                }            });        }        executorService.shutdown();        while(!executorService.isTerminated())        {            Thread.yield();        }        System.out.println("main end");    }}

执行结果：

pool-1-thread-1
pool-1-thread-1
pool-1-thread-1
pool-1-thread-1
pool-1-thread-1
main end

最近复习java基础，若有不妥之处欢迎指点......