Java线程池大小的设置方法实例

package com.base.demo.design.play;

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

/**
 * @Description: 线程池代码
 * @BelongsProject: base-demo-design
 * @BelongsPackage: com.base.demo.design.play
 * @Author: ChenYongJia
 * @CreateTime: 2021-08-14 15:26
 * @Email: chen87647213@163.com
 * @Version: 1.0
 */
public class TestThreadPoolExecutor {

    public static void main(String[] args) {
        // 创建使用单个线程的线程池
        ExecutorService es1 = Executors.newSingleThreadExecutor();
        for (int i = 0; i < 10; i++) {
            es1.submit(new Runnable() {
                @Override
                public void run() {
                    System.out.println(Thread.currentThread().getName() + "正在执行任务");
                }
            });
        }

        // 创建使用固定线程数的线程池
        ExecutorService es2 = Executors.newFixedThreadPool(3);
        for (int i = 0; i < 10; i++) {
            es2.submit(new Runnable() {
                @Override
                public void run() {
                    System.out.println(Thread.currentThread().getName() + "正在执行任务");
                }
            });
        }

        // 创建一个会根据需要创建新线程的线程池
        ExecutorService es3 = Executors.newCachedThreadPool();
        for (int i = 0; i < 20; i++) {
            es3.submit(new Runnable() {
                @Override
                public void run() {
                    System.out.println(Thread.currentThread().getName() + "正在执行任务");
                }
            });
        }

        // 创建拥有固定线程数量的定时线程任务的线程池
        ScheduledExecutorService es4 = Executors.newScheduledThreadPool(2);
        System.out.println("时间：" + System.currentTimeMillis());
        for (int i = 0; i < 5; i++) {
            es4.schedule(new Runnable() {
                @Override
                public void run() {
                    System.out.println("时间："+System.currentTimeMillis()+"--"+Thread.currentThread().getName() + "正在执行任务");
                }
            },3, TimeUnit.SECONDS);
        }

        // 创建只有一个线程的定时线程任务的线程池
        ScheduledExecutorService es5 = Executors.newSingleThreadScheduledExecutor();
        System.out.println("时间：" + System.currentTimeMillis());
        for (int i = 0; i < 5; i++) {
            es5.schedule(new Runnable() {
                @Override
                public void run() {
                    System.out.println("时间："+System.currentTimeMillis()+"--"+Thread.currentThread().getName() + "正在执行任务");
                }
            },3, TimeUnit.SECONDS);
        }
    }

}

public ThreadPoolExecutor(int corePoolSize,//线程池的核心线程数量
        int maximumPoolSize,//线程池的最大线程数
        long keepAliveTime,//当线程数大于核心线程数时，多余的空闲线程存活的最长时间
        TimeUnit unit,//时间单位
        BlockingQueue<Runnable> workQueue,//任务队列，用来储存等待执行任务的队列
        ThreadFactory threadFactory,//线程工厂，用来创建线程，一般默认即可
        RejectedExecutionHandler handler) //拒绝策略，当提交的任务过多而不能及时处理时，我们可以定制策略来处理任务

TimeUnit.DAYS;               //天
TimeUnit.HOURS;             //小时
TimeUnit.MINUTES;           //分钟
TimeUnit.SECONDS;           //秒
TimeUnit.MILLISECONDS;      //毫秒
TimeUnit.MICROSECONDS;      //微妙
TimeUnit.NANOSECONDS;       //纳秒

package com.base.demo.design.play;

import java.util.List;

/**
 * @Description: CPU测试
 * @BelongsProject: base-demo-design
 * @BelongsPackage: com.base.demo.design.play
 * @Author: ChenYongJia
 * @CreateTime: 2021-08-14 16:13
 * @Email: chen87647213@163.com
 * @Version: 1.0
 */
public class CPUTypeTest implements Runnable {

    /**
     * 整体执行时间，包括在队列中等待的时间
     */
    List<Long> wholeTimeList;

    /**
     * 真正执行时间
     */
    List<Long> runTimeList;

    private long initStartTime = 0;

    /**
     * 构造函数
     *
     * @param runTimeList
     * @param wholeTimeList
     * @return
     * @date 2021/8/14 16:13
     * @author ChenYongJia
     * @version 1.0
     */
    public CPUTypeTest(List<Long> runTimeList, List<Long> wholeTimeList) {
        initStartTime = System.currentTimeMillis();
        this.runTimeList = runTimeList;
        this.wholeTimeList = wholeTimeList;
    }

    /**
     * 判断素数
     *
     * @param number
     * @return boolean
     * @date 2021/8/14 16:13
     * @author ChenYongJia
     * @version 1.0
     */
    public boolean isPrime(final int number) {
        if (number <= 1)
            return false;

        for (int i = 2; i <= Math.sqrt(number); i++) {
            if (number % i == 0)
                return false;
        }
        return true;
    }


    /**
     * 计算素数
     *
     * @param lower
     * @param upper
     * @return int
     * @date 2021/8/14 16:14
     * @author ChenYongJia
     * @version 1.0
     */
    public int countPrimes(final int lower, final int upper) {
        int total = 0;
        for (int i = lower; i <= upper; i++) {
            if (isPrime(i))
                total++;
        }
        return total;
    }

    @Override
    public void run() {
        long start = System.currentTimeMillis();
        countPrimes(1, 1000000);
        long end = System.currentTimeMillis();


        long wholeTime = end - initStartTime;
        long runTime = end - start;
        wholeTimeList.add(wholeTime);
        runTimeList.add(runTime);
        System.out.println("单个线程花费时间：" + (end - start));
    }

}

package com.base.demo.design.play;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Vector;

/**
 * @Description: IO测试
 * @BelongsProject: base-demo-design
 * @BelongsPackage: com.base.demo.design.play
 * @Author: ChenYongJia
 * @CreateTime: 2021-08-14 16:18
 * @Email: chen87647213@163.com
 * @Version: 1.0
 */
public class IOTypeTest implements Runnable {

    /**
     * 整体执行时间，包括在队列中等待的时间
     */
    Vector<Long> wholeTimeList;

    /**
     * 真正执行时间
     */
    Vector<Long> runTimeList;

    private long initStartTime = 0;

    /**
     * 构造函数
     *
     * @param runTimeList
     * @param wholeTimeList
     */
    public IOTypeTest(Vector<Long> runTimeList, Vector<Long> wholeTimeList) {
        initStartTime = System.currentTimeMillis();
        this.runTimeList = runTimeList;
        this.wholeTimeList = wholeTimeList;
    }

    /**
     * IO操作
     *
     * @return void
     * @date 2021/8/14 16:18
     * @author ChenYongJia
     * @version 1.0
     */
    public void readAndWrite() throws IOException {
        File sourceFile = new File("D:/test.txt");
        //创建输入流
        BufferedReader input = new BufferedReader(new FileReader(sourceFile));
        //读取源文件,写入到新的文件
        String line = null;
        while ((line = input.readLine()) != null) {
            //System.out.println(line);
        }
        //关闭输入输出流
        input.close();
    }

    @Override
    public void run() {
        long start = System.currentTimeMillis();
        try {
            readAndWrite();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        long end = System.currentTimeMillis();


        long wholeTime = end - initStartTime;
        long runTime = end - start;
        wholeTimeList.add(wholeTime);
        runTimeList.add(runTime);
        System.out.println("单个线程花费时间：" + (end - start));
    }

}