Executors創建線程池的幾種方式以及使用

Java通過Executors提供四種線程池，分別為：

 

1.newCachedThreadPool創建一個可緩存線程池，如果線程池長度超過處理需要，可靈活回收空閑線程，若無可回收，則新建線程。

 

2.newFixedThreadPool 創建一個定長線程池，可控制線程最大並發數，超出的線程會在隊列中等待。

3.newScheduledThreadPool 創建一個定長線程池，支持定時及周期性任務執行。

 

4.newSingleThreadExecutor 創建一個單線程化的線程池，它只會用唯一的工作線程來執行任務，保證所有任務按照指定順序(FIFO, LIFO, 優先級)執行。

 

 

直接上代碼：

 

import lombok.experimental.Delegate;

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

public class ThreadUtil {

    //維護一個單例線程
    private static final ThreadUtil threadUtil = new ThreadUtil();
    
    // 代理模式  這樣可以直接調用父類中的方法
    // 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創建線程池
    @Delegate 
    public ExecutorService cachedThreadPool = Executors.newCachedThreadPool();
    
    //2.采用newFixedThreadPool創建線程池
    @Delegate
    public ExecutorService service = Executors.newFixedThreadPool(3);
    
    //3.采用newScheduledThreadPool 創建一個定長線程池 支持定時及周期性任務執行。
    // 使用方法： ThreadUtil.getInstance().schedule(new TestThread(),3, TimeUnit.SECONDS);
    @Delegate
    public ScheduledExecutorService newScheduledThreadPool = Executors.newScheduledThreadPool(2);
    

    //4.采用newSingleThreadExecutor 創建一個單線程化的線程池
    @Delegate
    public ExecutorService newSingleThreadExecutor = Executors.newSingleThreadExecutor();

    public static ThreadUtil getInstance() {
        return threadUtil;
    }

}

@Override
public String sendMsg() throws Exception {
    
    //把業務內容放在類中
    ThreadUtil.getInstance().execute(new TestThread());
    
    //或者這樣直接寫業務內容
    ThreadUtil.getInstance().execute( () -> {

            System.out.println("222");

             // 打印線程的內存地址
             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()));
    }
}