Executors创建线程池的几种方式以及使用

Java通过Executors提供四种线程池，分别为：

 

1.newCachedThreadPool创建一个可缓存线程池，如果线程池长度超过处理需要，可灵活回收空闲线程，若无可回收，则新建线程。

 

2.newFixedThreadPool 创建一个定长线程池，可控制线程最大并发数，超出的线程会在队列中等待。

3.newScheduledThreadPool 创建一个定长线程池，支持定时及周期性任务执行。

 

4.newSingleThreadExecutor 创建一个单线程化的线程池，它只会用唯一的工作线程来执行任务，保证所有任务按照指定顺序(FIFO, LIFO, 优先级)执行。

 

 

直接上代码：

 

import lombok.experimental.Delegate;

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

public class ThreadUtil {

    //维护一个单例线程
    private static final ThreadUtil threadUtil = new ThreadUtil();
    
    // 代理模式  这样可以直接调用父类中的方法
    // public interface ExecutorService extends Executor
    //public interface Executor {

    /**
     * Executes the given command at some time in the future.  The command
     * may execute in a new thread, in a pooled thread, or in the calling
     * thread, at the discretion of the {@code Executor} implementation.
     *
     * @param command the runnable task
     * @throws RejectedExecutionException if this task cannot be
     * accepted for execution
     * @throws NullPointerException if command is null
     */
    void execute(Runnable command);
    }
    
    // 1.采用newCachedThreadPool创建线程池
    @Delegate 
    public ExecutorService cachedThreadPool = Executors.newCachedThreadPool();
    
    //2.采用newFixedThreadPool创建线程池
    @Delegate
    public ExecutorService service = Executors.newFixedThreadPool(3);
    
    //3.采用newScheduledThreadPool 创建一个定长线程池 支持定时及周期性任务执行。
    // 使用方法： ThreadUtil.getInstance().schedule(new TestThread(),3, TimeUnit.SECONDS);
    @Delegate
    public ScheduledExecutorService newScheduledThreadPool = Executors.newScheduledThreadPool(2);
    

    //4.采用newSingleThreadExecutor 创建一个单线程化的线程池
    @Delegate
    public ExecutorService newSingleThreadExecutor = Executors.newSingleThreadExecutor();

    public static ThreadUtil getInstance() {
        return threadUtil;
    }

}

@Override
public String sendMsg() throws Exception {
    
    //把业务内容放在类中
    ThreadUtil.getInstance().execute(new TestThread());
    
    //或者这样直接写业务内容
    ThreadUtil.getInstance().execute( () -> {

            System.out.println("222");

             // 打印线程的内存地址
             System.out.println(System.identityHashCode(Thread.currentThread()));

             System.out.println(Thread.currentThread().getName());
        }
    );
    return "ok";
}

private class TestThread implements Runnable{

    @Override
    public void run() {
        System.out.println("111");

        System.out.println(Thread.currentThread().getName());

        System.out.println(System.identityHashCode(Thread.currentThread()));
    }
}