java - CompletableFuture 异常处理程序链

Question

是否可以使用 ComplatableFuture 在链中创建特殊处理程序？例如:我有这段代码，想法是如果位置服务方法抛出错误，则对 findClosest 方法进行通用调用(不带参数)。所以基本上，我想从这些方法中的任何一个返回 List 。这工作正常。但是在外部代码上，我需要触发一个事件以防方法调用是通用的(以防 locationService 失败)。

@Async
@Override
public CompletionStage<List<Closest>> getClosestByZip(final String zip) {

    return locationService.getCoordinates(zip)
            .handle((c, ex) -> ex == null ? closestService.findClosest(c) : closestService.findClosest())
            .thenCompose(list -> list);
}

在测试中，异常部分从未执行，因为 future 似乎已成功完成。

CompletableFuture<List<Closest>> closest = distanceService.getClosestByZip("111111")
            .exceptionally(ex -> {
                System.out.println("From exceptionally");
                return null;
            })
            .toCompletableFuture();


    try {
        List<Closest> list = closest.get();
        Assert.assertEquals(2, list.size());
    } catch (InterruptedException | ExecutionException e) {
        e.printStackTrace();
        Assert.fail("Exception was not caught");
    }

如何处理这种情况？

Answer 1

请检查这是否有帮助。

public class CompleteableFutureEx {

        public static void main(String[] args) throws Throwable {
            try {
                test(-1);
            } catch (ArithmeticException e) {
                System.out.println("Oops! We have an ArithmeticException");
            } 
            catch (IllegalArgumentException e) {
                System.out.println("Oops! We have an IllegalArgumentException");
            }
            catch (Exception e) {
                System.out.println("Oops! We have an Exception ");

            }
        }

        public static void test(int age) throws Throwable {

            try {
                CompletableFuture<String> maturityFuture = CompletableFuture.supplyAsync(() -> {
                    //ArithmeticException
                    //int age1 = age/0;
                    if (age < 0) {
                        throw new IllegalArgumentException("Age can not be negative");
                    }
                    if (age > 18) {
                        return "Adult";
                    } else {
                        return "Child";
                    }
                });
                maturityFuture.join();
            }catch (CompletionException ce) {
                throw ce.getCause();
            } 

        }

    }