一、Completable常用方法（二）

1. 收尾处理
   1.1 whenComplete方法
   当一个任务处理结束后，可以对得到的数据进行处理。

   CompletableFuture<String> future = CompletableFuture.supplyAsync(()->{
            return "hello";
        }).thenApply((w)->w+"world"+(1/0))
          .whenCompleteAsync((w,throwable)->{
            System.out.println(throwable.getMessage());
        });

在代码中有个ArithmeticException，在whenComplete时进行了处理。
2.2 handle方法
handle方法与whenComplete方法类似，不同的是handle方法中传入了一个BiFunction，意味着handle方法可以拥有返回值；

CompletableFuture<String> future = CompletableFuture.supplyAsync(()->{
            return "hello";
        }).thenApply((w)->w+"world"+(1/0))
          .handleAsync((w,throwable)->{
              System.out.println(throwable.getMessage());
              return "好嗨哦";
        });
        future.get();

1.3 thenAccept方法
thenAccept方法没有返回值，并且不能对异常进行处理。

CompletableFuture<Void> future = CompletableFuture.supplyAsync(()->{
            return "hello";
        }).thenApply((w)->w+"world")
          .thenAcceptAsync((w)->{
            System.out.println("真的有意思");
        });
        System.out.println(future.get());

2. one of two
   one of two 就是两者中任意一个完成就发出通知；
   2.1 acceptEither方法

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(()->{
            return "HELLOW";
        }).thenApply((w)->w+"WORLD");
        CompletableFuture<String> future = CompletableFuture.supplyAsync(()->{
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return "hello";
        }).thenApply((w)->w+"world");
        
        
CompletableFuture<Void> future2 = 
                future.acceptEitherAsync(future1,(w)->System.out.println("我看看是哪个Hello world\n"+w));

2.2 applyToEither方法
applyToEither 和acceptEither方法类似，只是applyToEither方法可以返回结果，applyToEither方法传入了Function接口

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(()->{
            return "HELLOW";
        }).thenApply((w)->w+"WORLD");
        CompletableFuture<String> future = CompletableFuture.supplyAsync(()->{
            return "hello";
        }).thenApply((w)->w+"world");
        
        
CompletableFuture<String> future2 = 
                future.applyToEither(future1,(w)->{return "我看看是哪个Hello world\n"+w;});
System.out.println(future2.get());

3 all of them
上面介绍了两个任务完成一个就会通知，下面介绍许多（大于两个）任务完成通知和许多任务完成才会通知。
3.1 allOf

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(()->{
            return "HELLOW";
        }).thenApply((w)->w+"WORLD");
        CompletableFuture<String> future2 = CompletableFuture.supplyAsync(()->{
            return "真的";
        }).thenApply((w)->w+"有意思");
        CompletableFuture<String> future = CompletableFuture.supplyAsync(()->{
            return "头发";
        }).thenApply((w)->w+"快没了");
        
CompletableFuture
     .allOf(future1,future2,future)
     .thenApply(v->Stream.of(future1,future2,future)
     .map(t -> {
    try {
        return t.get();
         } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
         } catch (ExecutionException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        }
        return null;
       })
       .collect(Collectors.toList()))
    .thenAccept(System.out::println);

3.2 anyOf

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(()->{
            return "HELLOW";
        }).thenApply((w)->w+"WORLD");
        CompletableFuture<String> future2 = CompletableFuture.supplyAsync(()->{
            return "真的";
        }).thenApply((w)->w+"有意思");
        CompletableFuture<String> future = CompletableFuture.supplyAsync(()->{
            return "头发";
        }).thenApply((w)->w+"快没了");
        
        CompletableFuture<Object> future3 = CompletableFuture
                .anyOf(future1,future2,future);
        System.out.println(future3.get());

4. 异常
   当执行过程中出现异常，可以对异常进行处理，当然使用get也可以抛出异常。

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(()->{
            return "HELLOW"+1/0;
        }).thenApply((w)->w+"WORLD").exceptionally((throwable)->{
            System.out.println(throwable);
            return null;
        });
System.out.println(future1.get());

以上就是CompletableFuture常用的方法，很多基于应用，深入底层的很少，希望对想快速入手的朋友有很大的帮助。