Java Thread - 如何实现生产者消费模式

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

public class Main {
  public static void main(String[] args) {
    int NTHREADS = 25;
    ExecutorService exec = Executors.newFixedThreadPool(NTHREADS);
    exec.submit(new MailConsumer());
    exec.submit(new MailProducer());
    System.out.println("inside main");
  }
}

class MailConsumer implements Runnable {
  @Override
  public void run() {
    while (true) {
      System.out.println("inside mail Consumer");
      System.out.println("Thread executing = "
          + Thread.currentThread().getName());
    }
  }
}

class MailProducer implements Runnable {
  @Override
  public void run() {
    while (true) {
      System.out.println("inside mail Producer");
      System.out.println("Thread executing = "
          + Thread.currentThread().getName());
    }
  }
}