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()));
     }
 }