11.线程池-4

execute和submit的区别

相同点：

1 都可以执行任务
2 参数都支持runnable

submit
execute

从图中可以看到两者的区别如下：

(1)来源

execute是Executor接口中的方法
submit是AbstractExecutorService中的方法

(2)接收参数类型

execute只能接受Runnable类型的任务
submit不管是Runnable还是Callable类型的任务都可以接受，但是Runnable返回值均为void，所以使用Future的get()获得的还是null

(3)返回值

execute没有返回值
submit有返回值，所以需要返回值的时候必须使用submit

(4)异常

execute中的是Runnable接口的实现，所以只能使用try、catch来捕获CheckedException，通过实现UncaughtExceptionHande接口处理UncheckedException
不管提交的是Runnable还是Callable类型的任务，如果不对返回值Future调用get()方法，都会吃掉异常。

package executors.threadpool;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
* <p></p>
*
* @author : wangdejian
* @version 1.0
* @date : 2021/8/4 21:01
*/
public class ThreadPoolExecute {
   public static void main(String[] args) {
       myTask();

   }

   public static void myTask() {

       ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(2,
               5,
               5,
               TimeUnit.MINUTES,
               new ArrayBlockingQueue<>(6));

       for (int i = 0; i < 12; i++) {
           int tmp = i;
           threadPoolExecutor.execute(() -> {

               try {
                   System.out.println("--->" + Thread.currentThread().getName() + "--" + tmp);
                   Thread.sleep(1_000);
               } catch (InterruptedException e) {
                   e.printStackTrace();
               }
           });
       }
       threadPoolExecutor.shutdown();
   }
}

public class ThreadPoolSubmit {
    public static void main(String[] args) throws ExecutionException, InterruptedException {

        Callable<Map<String, String>> callable = () -> {
            Map<String, String> map = new HashMap<>();
            try {
                Thread.sleep(1_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            String toString = Thread.currentThread().toString();

            String name = Thread.currentThread().getName();
            System.out.println("toString=" + toString + ";name=" + name);
            map.put("toString", Thread.currentThread().toString());
            map.put("name", name);

            return map;
        };

        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10,
                5, TimeUnit.MINUTES,
                new ArrayBlockingQueue<Runnable>(10));
        for (int i = 0; i < 10; i++) {
            Future<Map<String, String>> submit = threadPoolExecutor.submit(callable);
            System.out.println(submit.get().get("name"));
            System.out.println(submit.get().get("toString"));
        }

    }

}