多线程中Callable简单使用

Callable接口具备的特征如下

1.有简单的类型参数，与call()方法的返回类型相对应

2.声明了call方法，执行器运行任务时，该方法会被执行器执行，它必须返回声明中指定类型的对象

3.call()方法可以抛出任何一种校验异常，可以实现自己的执行器重载afterExecute方法来处理这些异常

package com.java.test.callable;

import lombok.extern.slf4j.Slf4j;

import java.util.UUID;
import java.util.concurrent.Callable;

/**
 * @author yourheart
 * @Description
 * @create 2022-10-19 22:50
 */
@Slf4j
public class ThreadCallable implements Callable<String> {
    /**
     * Computes a result, or throws an exception if unable to do so.
     *
     * @return computed result
     * @throws Exception if unable to compute a result
     */
    @Override
    public String call() throws Exception {
        Thread.sleep(5000);
        log.info("call执行中...");
        return UUID.randomUUID().toString();
    }
}

package com.java.test.callable;

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * @author yourheart
 * @Description
 * @create 2022-10-19 22:51
 */
@Slf4j
public class CallableTest {

    /**
     * 核心线程数
     */
    int corePoolSize = 3;
    /**
     * 最大线程数
     */
    int maximumPoolSize = 6;
    /**
     * 超过 corePoolSize 线程数量的线程最大空闲时间
     */
    long keepAliveTime = 2;
    /**
     * 以秒为时间单位
     */
    TimeUnit unit = TimeUnit.SECONDS;
    /**
     * 创建工作队列，用于存放提交的等待执行任务
     */
    BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<Runnable>(2);

    @Test
    /**
     * 执行器测试
     */
    public void  actuatorTest() throws ExecutionException, InterruptedException {
        ThreadCallable threadCallable = new ThreadCallable();
        ThreadPoolExecutor poolExecutor = new ThreadPoolExecutor(corePoolSize,
                maximumPoolSize,
                keepAliveTime,
                unit,
                workQueue,
                new ThreadPoolExecutor.AbortPolicy()) {
            @Override
            protected void afterExecute(Runnable r, Throwable t) {
                /**
                 * 当call方法中执行有错误，可以在这里处理
                 */
               // super.afterExecute(r, t);
                log.info("afterExecute 任务执行结束了....:{}",t);
            }
        };

        Future<String> submit = poolExecutor.submit(threadCallable);
        String result = submit.get();
        log.info("result:{}",result);
        poolExecutor.shutdown();

    }
    public void test() throws ExecutionException, InterruptedException {
        ThreadCallable threadCallable = new ThreadCallable();
        FutureTask<String> futureTask = new FutureTask<>(threadCallable);

        //启动线程，执行callable的业务
        new Thread(futureTask).start();
         //同步等待返回结果
        String result = futureTask.get();
        log.info("输出线程的返回结果:{}",result);
    }
}