java四种常用线程池的使用

public class ThreadPoolTest {
private static Logger log = Logger.getLogger(ThreadPoolTest.class);
/**
* 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
* (如果能用一个线程处理就会一直使用同一个线程,如果不够,会自动增加线程)
*/
@Test
public void newCachedThreadPool() {

ExecutorService cachedThreadPool = Executors.newCachedThreadPool();
final AtomicInteger ato = new AtomicInteger(0);
for (int i = 0; i < 10; i++) {
final int index = i;
/*
* try { Thread.sleep(index * 1000); //如果让线程等待 则始终是同一线程执行任务 }
* catch(InterruptedException e) { e.printStackTrace(); }
*/
cachedThreadPool.execute(new Runnable() {
@Override
public void run() {
ato.incrementAndGet();
System.out.println("线程号:" + Thread.currentThread().getId() + "  index:" + index);// 子线程打印出结果
}
});
}
log.info(ato);
System.out.println(ato);// 在主线程关闭之前一共执行了几次子线程 (JVM)
}

/**
* 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。 可以指定最大的并发线程数
*/
@Test
public void newFixedThreadPool() {
ExecutorService fixedThreadPool = Executors.newFixedThreadPool(3);
for (int i = 0; i < 10; i++) {
final int index = i;
fixedThreadPool.execute(new Runnable() {
@Override
public void run() {
System.out.println("线程号:" + Thread.currentThread().getId() + "  index:" + index);
}
});
}
}

/**
* 创建一个定长线程池，支持定时及周期性任务执行。
*/
@Test
public void newScheduledThreadPool() {
ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5);
/*
* scheduledThreadPool.schedule(new Runnable() {
*
* @Override public void run() { System.out.println("delay 3 seconds"
* );// 3s 以后执行 } }, 3, TimeUnit.SECONDS);
*/
scheduledThreadPool.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
System.out.println("delay 1 seconds, and excute every 3 seconds");

System.out.println("线程号:" + Thread.currentThread().getId());
}
}, 1, 3, TimeUnit.SECONDS);
try {
Thread.sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

/**
* 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。 单线程 顺序执行
*/
@Test
public void newSingleThreadExecutor() {
ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor();
for (int i = 0; i < 10; i++) {
final int index = i;
singleThreadExecutor.execute(new Runnable() {
@Override
public void run() {
System.out.println("线程号:" + Thread.currentThread().getId() + "  index:" + index);
}
});
}
}
}