我們來看一個簡單的執行緒池。

首先建立一個Runnable介面的實現類（當然也可以是Callable介面，我們上面也說過兩者的區別）

package com.study;

import java.util.Date;

public class MyRunnable implements Runnable{
    private String command;
    public MyRunnable(String s){
        this.command = s;
    }

    public void run() {
        System.out.println(Thread.currentThread().getName() 
 
+ " Start. Time = "+new Date());
        processCommand();
        System.out.println(Thread.currentThread().getName() + " End. Time = "+new Date());
    }

    private void processCommand(){
        try{
            Thread.sleep(5000);
        }catch (InterruptedException e){
            e.printStackTrace();
        }
    }

    @Override
    
 
public String toString() {
        return this.command;
    }
}

編寫測試程式，通過ThreadPoolExecutor建構函式自定義引數的方式來建立執行緒池。

package com.study;

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

public class ThreadPoolExecutorDemo {
    
 
//核心執行緒數
    private static final int CORE_POOL_SIZE = 5;
    //最大執行緒數
    private static final int MAX_POOL_SIZE = 10;
    //
    private static final int QUEUE_CAPACITY = 100;
    //等待時間
    private static final Long KEEP_ALIVE_TIME = 1L;

    public static void main(String[] args) {
        ThreadPoolExecutor executor = new ThreadPoolExecutor(
                CORE_POOL_SIZE,
                MAX_POOL_SIZE,
                KEEP_ALIVE_TIME,
                TimeUnit.SECONDS,//等待時間單位為秒
                new ArrayBlockingQueue<Runnable>(QUEUE_CAPACITY),//任務佇列
                new ThreadPoolExecutor.CallerRunsPolicy());//飽和策略

        for (int i = 0;i<10;i++){
            Runnable worker = new MyRunnable(""+i);
            executor.execute(worker);
        }
        executor.shutdown();
        while (executor.isTerminated()){
            System.out.println("Finished all threads");
        }
    }
}

可以看到以上程式碼我們指定了：

1、corePoolSize：核心執行緒數為5.

2、maximumPoolSize:最大執行緒數10

3、keepAliveTime：等待時間為1L；

4、unit：等待時間的單位為TimeUnit.SECONDS

5、workQueue:任務對流為ArrayBlockingQueue,並且容量為100；

6、handler：飽和策略為CallerRunsPolicy

輸出：

pool-1-thread-3 Start. Time = Tue Oct 13 19:02:04 CST 2020
pool-1-thread-1 Start. Time = Tue Oct 13 19:02:04 CST 2020
pool-1-thread-5 Start. Time = Tue Oct 13 19:02:04 CST 2020
pool-1-thread-4 Start. Time = Tue Oct 13 19:02:04 CST 2020
pool-1-thread-2 Start. Time = Tue Oct 13 19:02:04 CST 2020
pool-1-thread-5 End. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-2 End. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-1 End. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-3 End. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-4 End. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-3 Start. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-4 Start. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-2 Start. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-5 Start. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-1 Start. Time = Tue Oct 13 19:02:09 CST 2020
pool-1-thread-2 End. Time = Tue Oct 13 19:02:14 CST 2020
pool-1-thread-3 End. Time = Tue Oct 13 19:02:14 CST 2020
pool-1-thread-5 End. Time = Tue Oct 13 19:02:14 CST 2020
pool-1-thread-1 End. Time = Tue Oct 13 19:02:14 CST 2020
pool-1-thread-4 End. Time = Tue Oct 13 19:02:14 CST 2020