使用Callable和Future实现有返回值的异步

import java.util.concurrent.*;

public class TaskCallable implements Callable {
    @Override
    public Integer call() throws Exception {
        System.out.println("异步线程【" + Thread.currentThread().getName() + "】,计算中...");
        Thread.sleep(3000);
        return 2;
    }

    public static void main(String args[]) throws ExecutionException, InterruptedException {
        ExecutorService executor = Executors.newCachedThreadPool();
        TaskCallable task = new TaskCallable();
        Future result = executor.submit(task);

        System.out.println("主线程【" + Thread.currentThread().getName() + "】,等待结果...");
        System.out.println("主线程【" + Thread.currentThread().getName() + "】,异步线程" + result.get());
        executor.shutdown();
    }
}

结果：

主线程【main】,等待结果...
异步线程【pool-1-thread-1】,计算中...
主线程【main】,异步线程2