线程池工作原理

news2024/11/17 9:36:55

1：处理Runnable 任务的方法

package ThreadPooITest;


import java.util.concurrent.*;

//目标：线程池创建
public class ThreadPoolTest {
            public static void main(String[] args) {
              //1:通过ThreadPoolExector




             ExecutorService pool=  new ThreadPoolExecutor(3, 5, 8, TimeUnit.SECONDS,
                        new ArrayBlockingQueue<>(4),Executors.defaultThreadFactory(),
                        new ThreadPoolExecutor.CallerRunsPolicy());


                MyRunnble myRunnble = new MyRunnble();
               /* pool.execute(myRunnble);//线程池自动创建一个新的线程 。自动处理这个任务 自动执行
                pool.execute(myRunnble);//线程池自动创建一个新的线程 。自动处理这个任务 自动执行
                pool.execute(myRunnble);//线程池自动创建一个新的线程 。自动处理这个任务 自动执行
                pool.execute(myRunnble);//复用前面核心线程
                pool.execute(myRunnble);//复用前面核心线程
*/

                pool.execute(myRunnble);//线程池自动创建一个新的线程 。自动处理这个任务 自动执行
                pool.execute(myRunnble);//线程池自动创建一个新的线程 。自动处理这个任务 自动执行
                pool.execute(myRunnble);//线程池自动创建一个新的线程 。自动处理这个任务 自动执行
                pool.execute(myRunnble);
                pool.execute(myRunnble);
                pool.execute(myRunnble);
                pool.execute(myRunnble);
             //到了临时线程的创建时机了
                pool.execute(myRunnble);
                pool.execute(myRunnble);
                //看到新任务的拒绝的时机了
                pool.execute(myRunnble);


               // pool.shutdown();//等待线程都跑完再关闭线程池
             //  pool.shutdownNow(); //立刻关闭线程池


            }
}

package ThreadPooITest;

public class MyRunnble implements Runnable{
    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+"==> 输出666~~");

        try {
            Thread.sleep(Integer.MAX_VALUE);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

2：处理callable任务

package ThreadPooITest;


import java.util.concurrent.*;

//目标：线程池创建
public class ThreadPoolTest1 {
            public static void main(String[] args) throws Exception, InterruptedException {
              //1:通过ThreadPoolExector

             ExecutorService pool=  new ThreadPoolExecutor(3, 5, 8, TimeUnit.SECONDS,
                        new ArrayBlockingQueue<>(4),Executors.defaultThreadFactory(),
                        new ThreadPoolExecutor.CallerRunsPolicy());


        Future<String> f1= pool.submit(new MyCallable(100));
        Future<String> f2= pool.submit(new MyCallable(200));
        Future<String> f3= pool.submit(new MyCallable(300));
        Future<String> f4= pool.submit(new MyCallable(400));
       // Future<String> f5= pool.submit(new MyCallable(500));

                System.out.println(f1.get());
                System.out.println(f2.get());
                System.out.println(f3.get());
                System.out.println(f4.get());

            }
}

package ThreadPooITest;

import java.util.concurrent.Callable;

public class MyCallable implements Callable<String> {
    private int n;
    public MyCallable(int n){
        this.n=n;
    }

    @Override
    public String call() throws Exception {
        int sum=0;
        for (int i=1;i<=n;i++){
             sum+=i;
        }

        return Thread.currentThread().getName() +"线程求1-"+n+"的和是："+sum;
    }
}