scala 映射失败的 Future 的异常
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/18250888/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Map the Exception of a failed Future
提问by theon
What's the cleanest way to mapthe Exceptionof a failed Futurein scala?
什么是最干净的方式map的Exception的失败Future在Scala呢？
Say I have:
说我有：
import scala.concurrent._
import scala.concurrent.ExecutionContext.Implicits.global
val f = Future {
if(math.random < 0.5) 1 else throw new Exception("Oh no")
}
If the Future succeeds with 1, I'd like to keep that, however if it fails I would like to change the Exceptionto a different Exception.
如果 Future 成功1，我想保留它，但是如果它失败了，我想将 更改Exception为不同的Exception.
The best I could come up with is transform, however that requires me to make a needless function for the success case:
我能想到的最好的方法是转换，但这需要我为成功案例创建一个不必要的函数：
val f2 = f.transform(s => s, cause => new Exception("Something went wrong", cause))
Is there any reason there is no mapFailure(PartialFunction[Throwable,Throwable])?
有什么理由没有mapFailure(PartialFunction[Throwable,Throwable])吗？
回答by Viktor Klang
There is also:
还有：
f recover { case cause => throw new Exception("Something went wrong", cause) }
Since Scala 2.12 you can do:
从 Scala 2.12 开始，您可以执行以下操作：
f transform {
case s @ Success(_) => s
case Failure(cause) => Failure(new Exception("Something went wrong", cause))
}
or
或者
f transform { _.transform(Success(_), cause => Failure(new Exception("Something went wrong", cause)))}
回答by cmbaxter
You could try recoverWithas in:
您可以尝试recoverWith如下：
f recoverWith{
case ex:Exception => Future.failed(new Exception("foo", ex))
}
