线程池
ThreadPoolExecutor executor = new ThreadPoolExecutor(2, //核心线程数
5,//最大线程数
60L, //临时线程空闲时间
TimeUnit.SECONDS,//时间单位
new ArrayBlockingQueue<Runnable>(25), //线程池任务队列
new ThreadPoolExecutor.CallerRunsPolicy());//任务超出线程池能力异常处理
线程池手动创建方法如上所示，
核心线程数表示当线程池有任务进来时，会创建线程处理任务，最大不能超过这个数值，并且空闲时不会被释放；
最大线程数表示当核心线程数被占用，并且队列任务装满之后，会临时开启线程来处理后续加入的任务，临时线程最大数量 = 最大线程数-核心线程数；
临时线程空闲时间表示临时线程最大空闲时间，超过这个时间后，临时线程会释放
线程池任务队列表示当核心线程都被占用时，后续任务会被添加进队列中等待，等核心进程空闲时，会拿取队列中的任务进行处理。当队列装满后，会创建临时线程处理任务。
异常处理作用是当线程池任务队列装满，并且最大线程数创建满且都在执行任务，后续再有任务进来时，线程池会将任务交给异常处理消化
当需要线程池处理完事件，再回到主线程执行是，可以使用CountDownLatch让主线程阻塞，当CountDownLatch配置的任务数执行完成后，主线程再被唤醒
public static void test(boolean flag) {
System.out.println("开启线程池");
ThreadPoolExecutor executor = new ThreadPoolExecutor(5, //活动线程数
5,//最大线程数
60L, //临时线程空闲时间
TimeUnit.SECONDS,//时间单位
new ArrayBlockingQueue<>(30), //线程池任务队列
new ThreadPoolExecutor.CallerRunsPolicy());//任务超出线程池能力异常处理
executor.allowCoreThreadTimeOut(true);
int forCounts = 30;
CountDownLatch countd = new CountDownLatch(forCounts);// 线程池优先执行的计时器
syncSubmit1(executor, countd, forCounts);
try {
countd.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
syso(Thread.currentThread().getName());
//优雅释放线程池，等待线程池中正在执行任务的线程执行完后再进行释放
executor.shutdownNow();
//强制释放线程池，所有线程(包含正在执行任务的线程)立即停止并释放
//executor.shutdown();
while (true) {
if (executor.isShutdown()) {
syso("线程池释放了");
System.exit(0);
} else {
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
syso("线程池没有释放");
}
}
}
private static void syncSubmit1(ThreadPoolExecutor executor, CountDownLatch countd, int forCounts) {
for (int i = 0; i < forCounts; i++) {
executor.submit(new MyThread1(i, countd));
}
}
static class MyThread1 implements Runnable {
int i;
CountDownLatch countd;
public MyThread1(int i, CountDownLatch countd) {
this.i = i;
this.countd = countd;
}
@Override
public void run() {
if (countd.getCount() != 0) {
syso(" i = " + i + ",ThreadPoolExecutor'run's thread name = " + Thread.currentThread().getName());
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
countd.countDown();
}
}
代码执行结果：
开启线程池 i = 1,ThreadPoolExecutor'run's thread name = pool-1-thread-2 i = 0,ThreadPoolExecutor'run's thread name = pool-1-thread-1 i = 2,ThreadPoolExecutor'run's thread name = pool-1-thread-3 i = 3,ThreadPoolExecutor'run's thread name = pool-1-thread-4 i = 4,ThreadPoolExecutor'run's thread name = pool-1-thread-5 i = 5,ThreadPoolExecutor'run's thread name = pool-1-thread-1 i = 8,ThreadPoolExecutor'run's thread name = pool-1-thread-5 i = 7,ThreadPoolExecutor'run's thread name = pool-1-thread-2 i = 6,ThreadPoolExecutor'run's thread name = pool-1-thread-3 i = 9,ThreadPoolExecutor'run's thread name = pool-1-thread-4 i = 10,ThreadPoolExecutor'run's thread name = pool-1-thread-2 i = 14,ThreadPoolExecutor'run's thread name = pool-1-thread-4 i = 11,ThreadPoolExecutor'run's thread name = pool-1-thread-1 i = 13,ThreadPoolExecutor'run's thread name = pool-1-thread-3 i = 12,ThreadPoolExecutor'run's thread name = pool-1-thread-5 i = 15,ThreadPoolExecutor'run's thread name = pool-1-thread-4 i = 19,ThreadPoolExecutor'run's thread name = pool-1-thread-1 i = 18,ThreadPoolExecutor'run's thread name = pool-1-thread-3 i = 16,ThreadPoolExecutor'run's thread name = pool-1-thread-5 i = 17,ThreadPoolExecutor'run's thread name = pool-1-thread-2 i = 20,ThreadPoolExecutor'run's thread name = pool-1-thread-2 i = 24,ThreadPoolExecutor'run's thread name = pool-1-thread-1 i = 23,ThreadPoolExecutor'run's thread name = pool-1-thread-3 i = 22,ThreadPoolExecutor'run's thread name = pool-1-thread-5 i = 21,ThreadPoolExecutor'run's thread name = pool-1-thread-4 i = 25,ThreadPoolExecutor'run's thread name = pool-1-thread-5 i = 27,ThreadPoolExecutor'run's thread name = pool-1-thread-1 i = 28,ThreadPoolExecutor'run's thread name = pool-1-thread-2 i = 29,ThreadPoolExecutor'run's thread name = pool-1-thread-4 i = 26,ThreadPoolExecutor'run's thread name = pool-1-thread-3 main 线程池释放了
以上是线程池的基本使用，还有很多其他用法，慢慢研究吧
