Java异步编排CompletableFuture

• CompletableFuture
• • 介绍
  • 继承和实现
  • 主要方法
  • QuickStart
  • 练习1（双线程）
  • 练习（任意任务线完成执行新任务）
  • 多任务编排

CompletableFuture

介绍

在Java8之后提供了一个类以帮助我们进行多线程的异步编排工作，这就是CompletableFuture类，该类优化了我们对于异步任务的掌控，使我们可以自由编排任务先后顺序，返回值，中间条件

继承和实现

该类实现了：

1. Future
2. CompletionStage

主要方法

QuickStart

public class Test {static ThreadPoolExecutor executor = new ThreadPoolExecutor(5,10,10,TimeUnit.SECONDS,new LinkedBlockingQueue<>(100),Executors.defaultThreadFactory(),new ThreadPoolExecutor.AbortPolicy());public static void main(String[] args) throws ExecutionException, InterruptedException {System.out.println(Thread.currentThread().getName());//无返回结果CompletableFuture.runAsync(() -> {System.out.println(Thread.currentThread().getName());}, executor).whenComplete((res, exec) -> {//res为返回结构，exec为异常信息System.out.println(Thread.currentThread().getName() + "!");});//有返回结果，返回结果需要阻塞等待final CompletableFuture supplyAsync = CompletableFuture.supplyAsync(() -> {System.out.println(Thread.currentThread().getName());return "test supply";}, executor).whenCompleteAsync((res, exec) -> {System.out.println("r:" + res);System.out.println("e:" + exec);System.out.println(Thread.currentThread().getName() + "??");}, executor).exceptionally((e)->{System.out.println("e = " + e);return "ok";});System.out.println(supplyAsync.get());}
}

练习1（双线程）

public class Test2 {static ThreadPoolExecutor executor = new ThreadPoolExecutor(5,10,10,TimeUnit.SECONDS,new LinkedBlockingQueue<>(100),Executors.defaultThreadFactory(),new ThreadPoolExecutor.AbortPolicy());public static void main(String[] args) {final CompletableFuture future1 = CompletableFuture.runAsync(() -> {System.out.println("task1" + Thread.currentThread().getName());}, executor).thenRunAsync(() -> {System.out.println("task2" + Thread.currentThread().getName());}).thenAccept((e) -> {System.out.println(e);System.out.println("task3" + Thread.currentThread().getName());});final CompletableFuture future2 = CompletableFuture.supplyAsync(() -> {System.out.println("task4" + Thread.currentThread().getName());return "task4";}, executor).thenApplyAsync(res -> {System.out.println(res);return "task5";}).thenAccept(res -> {System.out.println(res);});future1.runAfterBothAsync(future2,()->{System.out.println("task6");},executor);}
}

练习（任意任务线完成执行新任务）

public class Test3 {static ThreadPoolExecutor executor = new ThreadPoolExecutor(5,10,10,TimeUnit.SECONDS,new LinkedBlockingQueue<>(100),Executors.defaultThreadFactory(),new ThreadPoolExecutor.AbortPolicy());public static void main(String[] args) {final CompletableFuture future1 = CompletableFuture.runAsync(() -> {System.out.println("task1" + Thread.currentThread().getName());}, executor).thenRunAsync(() -> {System.out.println("task2" + Thread.currentThread().getName());}).thenAccept((e) -> {System.out.println(e);System.out.println("task3" + Thread.currentThread().getName());});final CompletableFuture future2 = CompletableFuture.supplyAsync(() -> {System.out.println("task4" + Thread.currentThread().getName());return "task4";}, executor).thenApplyAsync(res -> {System.out.println(res);return "task5";}).thenAccept(res -> {System.out.println(res);});//        future1.runAfterEither(future2,()->{
//            System.out.println(Thread.currentThread().getName());
//            System.out.println("either task");
//        });future1.runAfterEitherAsync(future2,()->{System.out.println(Thread.currentThread().getName());System.out.println("either task");});}
}

多任务编排

前面我们了解到双任务编排，那么大于等于3条任务线的时候我们就需要多任务编排了，主要用到anyOf和allOf方法进行，最后完成后会回到主线程

final CompletableFuture newF = CompletableFuture.allOf(future1, future2, future3);
//用于对任务线进行阻塞,join和get都可以，看场景，单纯阻塞无返回值建议join
newF.join();
newF.get();