在Scala中,我们可以将finally block 中的异常抛出添加回原始异常作为抑制异常吗?
在Java中,如果我们在try block 中遇到异常,然后在finally block 中遇到另一个异常,则第二个异常将作为抑制异常添加回第一个异常。因此,第二个异常不会掩盖第一个异常,我们仍然可以通过检查其抑制的异常来分析发生了什么。
import java.util.stream.Stream;
class Scratch {
static class MyCloseable implements AutoCloseable {
@Override
public void close() throws Exception {
throw new Exception("FROM CLOSE METHOD");
}
}
public static void main(String[] args) {
try {
try (final MyCloseable closeable = new MyCloseable()){
throw new Exception("From Try Block");
}
} catch (Throwable t) {
System.out.println(t);
Stream.of(t.getSuppressed()).forEach(System.out::println);
}
}
}
会抛出异常
java.lang.Exception:来自 Try block
java.lang.Exception:来自 CLOSE 方法
但是,Scala 似乎只是重新抛出第二个异常(从 finally block 抛出)并忽略第一个异常(从 try block 抛出)。
try {
try {
throw new Exception("From Try Block")
} finally {
throw new Exception("From Final Block")
}
} catch {
case e => e :: e.getSuppressed().toList
}
上面的代码将仅返回第二个异常(从最终 block 抛出)。但是,我希望有一种方法可以同时获得两个异常。
有什么办法可以更好地编写上面的代码吗?
最佳答案
由于 Scala 不支持 java 的 try-with-resources 构造,我想有一个明显的方法可以使上面的代码以更好的方式 = 记住第一个异常:
try {
var te: Option[Throwable] = None
try {
throw new Exception("From Try Block")
} catch {
case t: Throwable =>
te = Some(t)
throw t
} finally {
try {
throw new Exception("From Final Block")
} catch {
case fe: Throwable =>
throw te.map { e => e.addSuppressed(fe); e }.getOrElse(fe)
}
}
} catch {
case e: Throwable =>
(e :: e.getSuppressed().toList).foreach(println)
}
输出:
java.lang.Exception: From Try Block
java.lang.Exception: From Final Block
下面是我在实际项目中使用的更好的方法:
def withResources[T <: AutoCloseable, V](r: => T)(f: T => V): V = {
val resource: T = r
var e: Option[Throwable] = None
try f(resource)
catch {
case t: Throwable =>
e = Some(t)
throw t
} finally e.fold(resource.close())(te =>
try resource.close()
catch {
case t: Throwable =>
te.addSuppressed(t)
throw te
})
}
val resource = new AutoCloseable {
override def close(): Unit = throw new Exception("From Final Block")
}
try {
withResources(resource)(_ => throw new Exception("From Try Block"))
} catch {
case e: Throwable =>
(e :: e.getSuppressed().toList).foreach(println)
}
输出:
java.lang.Exception: From Try Block
java.lang.Exception: From Final Block
关于scala - Scala 中有抑制异常吗?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/56064395/