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如何在不知道异常类型的情况下捕获python中的异常并获取对该异常的引用?

jython exception-handling python

TM. Randy Simon · 技术社区 · 15 年前

我想知道我怎样才能赶上任何凸起对象(即不扩展的类型 Exception ),并且仍然可以获得对它的引用。

我在使用Jython时遇到了这样的愿望。调用Java方法时,如果该方法引发异常,它将不会扩展Python的

try:
    # some call to a java lib that raises an exception here
except Exception, e:
    # will never be entered

try:
    # some call to a java lib that raises an exception here
except:
    # will enter here, but there's no reference to the exception that was raised

我可以通过导入Java异常类型并显式捕获它来解决这个问题,但这使得编写通用异常处理包装器/装饰器变得困难/不可能。

是否有一种方法可以捕获某些任意异常,并在 except 块

我希望我正在制作的异常处理装饰器能够用于Python项目,而不仅仅是Jython项目。我想避免进口 java.lang.Exception 因为这只是Jython的专利。例如,我想我可以做这样的事情(但我没有尝试过),但如果可以的话,我想避免。

try:
    # some function that may be running jython and may raise a java exception
except (Exception, java.lang.Exception), e:
    # I imagine this would work, but it makes the code jython-only

3 回复 | 直到 15 年前

Brian McKenna 15 年前

您可以使用 sys 模块。 sys.exc_info 是类型、实例和回溯的元组。

import sys

try:
    # some call to a java lib that raises an exception here
except:
    instance = sys.exc_info()[1]

Adrian Mehlig 11 年前

FWIW,我发现如果将此导入添加到Jython脚本中:

from java.lang import Exception

except Exception, e:

它会抓住你的 二者都 Python异常和

mike rodent 11 年前

只为任何有兴趣的人。。。我花了一点时间测试这些东西,因为我想知道如何获得正确的堆栈跟踪,不管是抛出Python异常(实际上是基类BaseException)还是java.lang.Throwable(异常、错误等的java基类)。。。此代码说明了如何正确捕获所有行号引用。

import sys
import traceback
import java

print "hello world"

def custom_hook( type, exc, tb ):
  if isinstance( sys.exc_info()[ 1 ], java.lang.Throwable ):
    sys.stderr.write( "AS JAVA:\n" )
    sys.exc_info()[ 1 ].printStackTrace() # java part
  else:
    sys.stderr.write( "NO JAVA TRACE:\n" )
  sys.stderr.write( "AS PYTHON:\n" )
  traceback.print_exc()

# useful for custom exception handling!
sys.excepthook = custom_hook  

def handle_exc():
# generate either a java.lang.Throwable (uncomment the next line and comment out "a = 16 / 0"
#  java.lang.String( None )
# OR... a python-style BaseException:
  a = 16 / 0 

class Task( java.lang.Runnable ):
  def run( self ):
    # NB the problem with all this stuff is that the Java stack trace shows
    # a java.lang.Throwable occurring at the last line of this code block...
#    print "lots of stuff first"
#    print "lots 2"
#    handle_exc()
#    print "lots 3"
#    print "lots of stuff after"

    try:
      print "lots of stuff first"
      print "lots 2"
      handle_exc()
      print "lots 3"
      print "lots of stuff after"
    # NB do not catch both (Python) BaseException and java.lang.Throwable...   
#    except ( BaseException, java.lang.Throwable ), e:
    # the above means that the line no. in handle_exc is not shown when a BaseException  
    # is thrown...
    except java.lang.Throwable, t:
      tb = sys.exc_info()[ 2 ] 
      sys.stderr.write( "java.lang.Throwable thrown at: %s\n" % tb.tb_lineno )
      raise t

java.awt.EventQueue.invokeAndWait( Task() )

def throw_trap( function ):
  def wrapper(*args, **kvargs):
    try:
      return function( *args, **kvargs )
    except  java.lang.Throwable, t:
      tb = sys.exc_info()[ 2 ]
      while( tb ): 
        sys.stderr.write( "thrown at: %s\n" % tb.tb_lineno )
        tb = tb.tb_next
      raise t
  return wrapper



def handle_exc():
  java.lang.String( None )
#  a = 16 / 0 


class Task( java.lang.Runnable ):
  @throw_trap
  def run( self ):
    print "lots of stuff first"
    print "lots 2"
    handle_exc()
    print "lots 3"
    print "lots of stuff after"

java.awt.EventQueue.invokeAndWait( Task() )