java 创建一个线程池

Java中可以使用ThreadPoolExecutor类来创建一个线程池。下面是一个简单的示例：

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MyThreadPool {

    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(5);

        for (int i = 0; i < 10; i++) {
            Runnable worker = new MyWorkerThread("" + i);
            executorService.execute(worker);
        }

        executorService.shutdown();
        while (!executorService.isTerminated()) {
        }

        System.out.println("All tasks completed");
    }
}

class MyWorkerThread implements Runnable {

    private String message;

    public MyWorkerThread(String message) {
        this.message = message;
    }

    public void run() {
        System.out.println(Thread.currentThread().getName() + " (Start) message = " + message);
        processMessage();
        System.out.println(Thread.currentThread().getName() + " (End)");
    }

    private void processMessage() {
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

在这个示例中，我们使用Executors类中的newFixedThreadPool方法来创建一个固定大小为5的线程池。我们创建了10个任务，每个任务都是一个MyWorkerThread实例，并将它们提交给线程池执行。任务的执行是通过调用executorService.execute(worker)实现的。最后，我们调用shutdown方法来关闭线程池，并等待所有任务完成后打印"All tasks completed"。