一、Completable常用方法（二）

1. 收尾處理
   1.1 whenComplete方法
   當(dāng)一個任務(wù)處理結(jié)束后，可以對得到的數(shù)據(jù)進(jìn)行處理。

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

在代碼中有個ArithmeticException，在whenComplete時進(jìn)行了處理。
2.2 handle方法
handle方法與whenComplete方法類似，不同的是handle方法中傳入了一個BiFunction，意味著handle方法可以擁有返回值；

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方法沒有返回值，并且不能對異常進(jìn)行處理。

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 就是兩者中任意一個完成就發(fā)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("我看看是哪個Hello world\n"+w));

2.2 applyToEither方法
applyToEither 和acceptEither方法類似，只是applyToEither方法可以返回結(jié)果，applyToEither方法傳入了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 "我看看是哪個Hello world\n"+w;});
System.out.println(future2.get());

3 all of them
上面介紹了兩個任務(wù)完成一個就會通知，下面介紹許多（大于兩個）任務(wù)完成通知和許多任務(wù)完成才會通知。
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 "頭發(fā)";
        }).thenApply((w)->w+"快沒了");
        
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 "頭發(fā)";
        }).thenApply((w)->w+"快沒了");
        
        CompletableFuture<Object> future3 = CompletableFuture
                .anyOf(future1,future2,future);
        System.out.println(future3.get());

4. 異常
   當(dāng)執(zhí)行過程中出現(xiàn)異常，可以對異常進(jìn)行處理，當(dāng)然使用get也可以拋出異常。

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，很多基于應(yīng)用，深入底層的很少，希望對想快速入手的朋友有很大的幫助。