ThreadPoolUtil工具类

package com.example.threadpool.service;

import lombok.NonNull;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;

/**

• @program: demo-threadpool
• @description
• @author: tina.liu
• @create: 2022-04-03 20:40
  **/

@Slf4j
public class ThreadPoolUtil {

public static final ThreadPoolUtil EXCUTOR = new ThreadPoolUtil();
//核心线程池的数量，同时能够执行的线程数量
private int corePoolSize;
//最大线程池数量，表示当缓冲队列满的时候能继续容纳的等待任务的数量
private int maxPoolSize;
//存活时间
private long keepAliveTime = 1;
private TimeUnit unit = TimeUnit.HOURS;
private ThreadPoolExecutor executor;

private ThreadPoolUtil() {
    //给corePoolSize赋值：当前设备可用处理器核心数*2 + 1,能够让cpu的效率得到最大程度执行（有研究论证的）
    corePoolSize = Runtime.getRuntime().availableProcessors() * 2 + 1;
    maxPoolSize = corePoolSize;
    executor = new ThreadPoolExecutor(
            //当某个核心任务执行完毕，会依次从缓冲队列中取出等待任务
            corePoolSize,
            // 然后new LinkedBlockingQueue<Runnable>(),然后maximumPoolSize,但是它的数量是包含了corePoolSize的
            maxPoolSize,
            //表示的是maximumPoolSize当中等待任务的存活时间
            keepAliveTime,
            unit,
            //缓冲队列，用于存放等待任务，Linked的先进先出
            new LinkedBlockingQueue<Runnable>(),
            new DefaultThreadFactory(Thread.NORM_PRIORITY, "thread-pool-"),
            new ThreadPoolExecutor.AbortPolicy()
    );
    log.info("Class ThreadPoolUtil field corePoolSize ={},maxPoolSize ={} ", corePoolSize, maxPoolSize);
}

/**
 * 执行任务 无返回值
 *
 * @param runnable
 */
public void execute(Runnable runnable) {
    if (runnable != null) {
        executor.execute(runnable);
    }
}

/**
 * 执行任务 有返回值
 *
 * @param callable
 */
public <T> T executeReturn(Callable<T> callable) {
    try {
        return executor.submit(callable).get();
    } catch (Exception e) {
        log.error("Class ThreadPoolUtil executeReturn fail message :{}",e.getMessage());
    }
    return null;
}




/**
 * 执行任务 有返回值
 *
 * @param callables
 */
public <T> List<Future<T>> executeReturn(List<Callable<T>> callables) {
    try {
        return executor.invokeAll(callables);
    } catch (Exception e) {
        log.error("Class ThreadPoolUtil executeReturn fail message :{}",e.getMessage());
    }
    return null;
}


/**
 * 移除任务
 *
 * @param runnable
 */
public void remove(Runnable runnable) {
    if (runnable != null) {
        executor.remove(runnable);
    }
}

private static class DefaultThreadFactory implements ThreadFactory {

    //线程池的计数
    private static final AtomicInteger poolNumber = new AtomicInteger(1);
    //线程的计数
    private final AtomicInteger threadNumber = new AtomicInteger(1);
    private final ThreadGroup group;
    private final String namePrefix;
    private final int threadPriority;

    DefaultThreadFactory(int threadPriority, String threadNamePrefix) {
        this.threadPriority = threadPriority;
        this.group = Thread.currentThread().getThreadGroup();
        this.namePrefix = threadNamePrefix + poolNumber.getAndIncrement() + "-thread-";
    }

    @Override
    public Thread newThread(@NonNull Runnable r) {
        Thread thread = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0);
        // 返回True该线程就是守护线程
        // 守护线程应该永远不去访问固有资源，如：数据库、文件等。因为它会在任何时候甚至在一个操作的中间发生中断。
        if (thread.isDaemon()) {
            thread.setDaemon(false);
        }
        thread.setPriority(threadPriority);
        return thread;
    }
}

}