java - 让 CompletableFuture 异常()处理 supplyAsync() 异常

Question

问题很简单:我正在寻找一种优雅的使用方式 CompletableFuture#exceptionally与 CompletableFuture#supplyAsync 一起.这是行不通的:

private void doesNotCompile() {
    CompletableFuture<String> sad = CompletableFuture
            .supplyAsync(() -> throwSomething())
            .exceptionally(Throwable::getMessage);
}

private String throwSomething() throws Exception {
    throw new Exception();
}

我想到了背后的想法 exceptionally()正是为了处理 Exception 的情况被抛出。但是，如果我这样做，它会起作用:

private void compiles() {
    CompletableFuture<String> thisIsFine = CompletableFuture.supplyAsync(() -> {
        try {
            throwSomething();
            return "";
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }).exceptionally(Throwable::getMessage);
}

我可以使用它，但它看起来很糟糕并且使事情更难维护。有没有办法保持这种清洁而不需要转换所有 Exception进入 RuntimeException ?

Answer 1

这可能不是一个 super 流行的库，但我们在内部使用它(有时我也在那里做一些工作；虽然次要):NoException .写得真好，符合我的口味。这不是它唯一的东西，但绝对涵盖了您的用例:
这是一个示例:

import com.machinezoo.noexception.Exceptions;
import java.util.concurrent.CompletableFuture;

public class SO64937499 {

    public static void main(String[] args) {
        CompletableFuture<String> sad = CompletableFuture
            .supplyAsync(Exceptions.sneak().supplier(SO64937499::throwSomething))
            .exceptionally(Throwable::getMessage);
    }

    private static String throwSomething() throws Exception {
        throw new Exception();
    }
}

或者您可以自己创建这些:

final class CheckedSupplier<T> implements Supplier<T> {

    private final SupplierThatThrows<T> supplier;

    CheckedSupplier(SupplierThatThrows<T> supplier) {
        this.supplier = supplier;
    }

    @Override
    public T get() {
        try {
            return supplier.get();
        } catch (Throwable exception) {
            throw new RuntimeException(exception);
        }
    }
}



@FunctionalInterface
interface SupplierThatThrows<T> {

    T get() throws Throwable;
}

和用法:

 CompletableFuture<String> sad = CompletableFuture
        .supplyAsync(new CheckedSupplier<>(SO64937499::throwSomething))
        .exceptionally(Throwable::getMessage);