线程池：1.出现版本：JDK1.52.包：java.util.concurrent3.Executors类 -->工厂类1.三个静态方法：static ExecutorService newCachedThreadPool() 创建新的线程池对象Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available.static ExecutorService newFixedThreadPool(int nThreads) 创建目标个数的线程池Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue.tatic ExecutorService newSingleThreadExecutor() 创建一个线程Creates an Executor that uses a single worker thread operating off an unbounded queue.2.ExecutorService 是一个接口<T> Future<T> submit(Callable<T> task)Submits a value-returning task for execution and returns a Future representing the pending results of the task.Future<?> submit(Runnable task)Submits a Runnable task for execution and returns a Future representing that task.3.Future 是运行后的结果Callable是一个接口，call（）方法有返回值public interface Callable<V>4.实现线程的三种方式：1.继承Thead 类2.实现Runnable 接口3.实现 Callable 接口-----只要线程池支持，Thead不支持
//第一个class文件
public class RunnablePoolDemo implements Runnable{public void run(){for(int x =0;x<20;x++){System.out.println(Thread.currentThread().getName()+"run.."+x);}}
}//第二个class文件
import java.util.concurrent.Callable;/*** @author Alina* @date 2021年12月25日 11:59 下午*/
public class CallableSumDemo implements Callable<Integer> {private Integer num = 0;public CallableSumDemo(Integer num) {this.num = num;}public Integer call() {int sum = 0;for (int x = 0;x<=num;x++){sum = sum +x;}return sum;}
}//主文件package thread;import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;/*** @author Alina* @date 2021年12月25日 11:17 下午* 创建线程池* 实现方法：* 1.创建 Executors 类，静态调用，创建两个线程池* 3.返回对象：ExecutorService**/
public class TheadPoolDemo {public static void main(String[] args) throws Exception{method_3();}public static void method_3 () throws ExecutionException, InterruptedException {ExecutorService es3 = Executors.newFixedThreadPool(2);Future<Integer> f1 = es3.submit(new CallableSumDemo(100));Future<Integer> f2 = es3.submit(new CallableSumDemo(200));int sum1 = f1.get();int sum2 = f2.get();System.out.println(sum1);System.out.println(sum2);es3.shutdown();}public static void method_2() throws Exception{ExecutorService es2 = Executors.newFixedThreadPool(2);Future<String> ft = es2.submit(new CallablePoolDemo());String name = ft.get();System.out.println(name);}public static void method_1(){ExecutorService es = Executors.newFixedThreadPool(2);es.submit(new RunnablePoolDemo());es.submit(new RunnablePoolDemo());es.shutdown();}
}
