java線程池推薦使用方式：ThreadPoolExecutor 簡單使用代碼示例

java的多線程推薦使用ThreadPoolExecutor來創建和使用線程池，廢話不多說：

package com.zhh;

import java.util.concurrent.*;

/**
 * @Author: zhh
 * @Date: 2019/11/11 15:20
 * @Description: This is an example of ThreadPoolExecutor usage.
 */
public class TestThreadPool {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService = getExecutorService();
        Future<String> f1 = submitTask(executorService, new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("Thread 1 is running……");
                Thread.sleep(5000); //睡5秒
                return "1 done!";
            }
        });
        Future<String> f2 = submitTask(executorService, new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("Thread 2 is running……");
                Thread.sleep(5000); //睡5秒
                return "2 done!";
            }
        });

        Future<String> f3 = submitTask(executorService, new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("Thread 3 is running……");
                Thread.sleep(5000); //睡5秒
                return "3 done!";
            }
        });

        Future<String> f4 = submitTask(executorService, new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("Thread 4 is running……");
                Thread.sleep(5000); //睡5秒
                return "4 done!";
            }
        });

        Future<String> f5 = submitTask(executorService, new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("Thread 5 is running……");
                Thread.sleep(5000); //睡5秒
                return "5 done!";
            }
        });
        Future<String> f6 = submitTask(executorService, new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("Thread 6 is running……");
                Thread.sleep(5000); //睡5秒
                return "6 done!";
            }
        });

        System.out.println(f1.get());
        System.out.println(f2.get());
        System.out.println(f3.get());
        System.out.println(f3.get());
        System.out.println(f5.get());
    }

    /**
     * 必須要自行處理提交異常，否則線程執行會中斷，即使提交成功也無法繼續執行
     * @param executorService
     * @param callable
     * @return
     */
    public static Future<String> submitTask(ExecutorService executorService, Callable<String> callable){
        try{
            Future<String> f = executorService.submit(callable);
            return f;
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

    public static ExecutorService getExecutorService(){
        int poolSize = Runtime.getRuntime().availableProcessors();
        System.out.println(poolSize);
        //超出隊列的size，再繼續添加任務，會直接根據RejectedExecutionHandler來決定處理新任務的策略
        //AbortPolicy : 對於超出隊列大小後面再添加的任務直接拋異常
        //DiscardPolicy	: 什麼也不做，直接忽略
        BlockingQueue<Runnable> queue = new ArrayBlockingQueue<>(1);
        RejectedExecutionHandler handler = new ThreadPoolExecutor.AbortPolicy();
        ExecutorService executorService = new ThreadPoolExecutor(poolSize, poolSize,
                0, TimeUnit.SECONDS, queue, handler);
        return executorService;
    }

}