創建多執行緒的4種方式

• - 繼承Thread
• - 實作Runnable介面
• - 實作Callable介面
• - 使用執行緒池ThreadPoolExecutor

- 繼承Thread

繼承Thread類，重寫run方法實作多執行緒

package com.noneplus;

class Task1 extends Thread {

    @Override
    public void run() {

        for (int i = 0; i < 10; i++) {
            System.out.println("Task1輸出：" + i);
        }
    }
}

class Task2 extends Thread {

    @Override
    public void run() {

        for (int i = 0; i < 10; i++) {
            System.out.println("                 Task2輸出：" + i);
        }
    }
}

/**
 * @Description: 繼承Thread，重寫run方法，實作多執行緒
 * @Author noneplus
 * @Date 2020/8/3 17:34
 */
public class ExtendThread {

    public static void main(String[] args) {

        Task1 task1 = new Task1();
        task1.start();

        Task2 task2 = new Task2();
        task2.start();

        for (int i = 0; i < 10; i++) {
            System.out.println("                                         mainTask輸出：" + i);
        }

        //3個執行緒的執行順序由CPU的執行緒調度決定

    }
}

- 實作Runnable介面

Runnable介面解決了單繼承的問題

package com.noneplus;

class Task3 implements Runnable {

    @Override
    public void run() {

        for (int i = 0; i < 10; i++) {
            System.out.println("Task1輸出：" + i);
        }
    }
}

class Task4 implements Runnable {

    @Override
    public void run() {

        for (int i = 0; i < 10; i++) {
            System.out.println("                      Task2輸出：" + i);
        }
    }
}

/**
 * @Description: 實作Runnable介面，實作多執行緒，彌補單繼承的問題
 * @Author noneplus
 * @Date 2020/8/3 17:34
 */
public class ImplementRunnable {

    public static void main(String[] args) {

        Task3 runnable3 = new Task3();
        Task4 runnable4 = new Task4();

        Thread task3 = new Thread(runnable3);
        Thread task4 = new Thread(runnable4);

        task3.start();
        task4.start();

        for (int i = 0; i < 10; i++) {
            System.out.println("                                                                  " +
                    " mainTask輸出：" + i);
        }

        //3個執行緒的執行順序由CPU的執行緒調度決定

    }
}

- 實作Callable介面

Callable支持回傳值（但用多執行緒加回傳值有點奇怪）

package com.noneplus;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

class Task5 implements Callable {

    @Override
    public Integer call() throws Exception {
        Integer i = 0;
        for (; i < 10; i++) {
            System.out.println("Task5輸出：" + i);
        }
        return i;
    }
}

class Task6 implements Callable {

    @Override
    public Integer call() throws Exception {
        Integer i = 0;
        for (; i < 10; i++) {
            System.out.println("             Task6輸出：" + i);
        }
        return i;
    }
}


/**
 * @Description: 實作Callable介面，可以定義回傳值
 * @Author noneplus
 * @Date 2020/8/3 17:53
 */
public class ImplementCallable {

    public static void main(String[] args) throws ExecutionException, InterruptedException {

        for (int i = 0; i < 10; i++) {
            System.out.println("                                         mainTask輸出：" + i);
        }

        FutureTask<Integer> futureTask = new FutureTask<Integer>(new Task5());
        FutureTask<Integer> futureTask1 = new FutureTask<Integer>(new Task6());

        Thread thread = new Thread(futureTask);
        Thread thread1 = new Thread(futureTask1);

        thread.start();
        thread1.start();

        System.out.println("任務回傳結果："+futureTask.get());
        System.out.println("任務回傳結果："+futureTask1.get());

    }
}

- 使用執行緒池ThreadPoolExecutor

package com.noneplus;

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

class Task7 implements Runnable {
    @Override
    public void run() {

        for (int i = 0; i < 10; i++) {
            System.out.println("Task7輸出：" + i + "當前執行緒" + Thread.currentThread().getName());
        }
    }
}

class Task8 implements Runnable {
    @Override
    public void run() {

        for (int i = 0; i < 10; i++) {
            System.out.println("Task8輸出：" + i + "當前執行緒" + Thread.currentThread().getName());

        }

    }
}

/**
 * @Description: 使用執行緒池創建執行緒池，實作執行緒復用和管理
 * @Author noneplus
 * @Date 2020/8/5 15:38
 */
public class ThreadPool {

    public static void main(String[] args) {
        /**
         * 阿里推薦：ThreadPoolExecutor
         * ```
         * public ThreadPoolExecutor(int corePoolSize,
         *                               int maximumPoolSize,
         *                               long keepAliveTime,
         *                               TimeUnit unit,
         *                               BlockingQueue<Runnable> workQueue)
         * ```
         * 1、corePoolSize 核心執行緒數大小，當執行緒數 < corePoolSize ，會創建執行緒執行 runnable
         *
         * 2、maximumPoolSize 最大執行緒數， 當執行緒數 >= corePoolSize的時候，會把 runnable 放入 workQueue中
         *
         * 3、keepAliveTime 保持存活時間，當執行緒數大于corePoolSize的空閑執行緒能保持的最大時間，
         *
         * 4、unit 時間單位
         *
         * 5、workQueue 保存任務的阻塞佇列
         *
         * 6、threadFactory 創建執行緒的工廠
         *
         * 7、handler 拒絕策略
         *
         */
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10, 3, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(3));

        for (int i=0;i<10;i++)
        {
            threadPoolExecutor.execute(new Task7());

            threadPoolExecutor.execute(new Task8());
        }


    }
}

標籤：Java

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