Windows批处理编程是否支持异常处理？如果没有,有没有办法有效地模拟批处理文件中的异常处理？
我想要能够在任何CALL级别的批处理脚本中“抛出异常”,并且CALL堆栈重复弹出,直到找到一个活动的“TRY块”,因此“CATCH块”可以处理异常完全进行或进行一些清理,并继续弹出CALL堆栈.如果从未处理异常,则会终止批处理,并且控制将返回到具有错误消息的命令行上下文.
已经有couple posted ways to terminate batch processing at any CALL depth,但是这些技术中没有一个允许通常通过异常处理在其他语言中提供的任何结构化清理活动.
注意：这是一个我已经知道最近才发现的好答案的情况,我想分享这个信息
Windows批处理脚本当然没有任何正式的异常处理 – 考虑到这个语言是多么原始的,这并不奇怪.我从来没有想过有效的异常处理可能被黑客入侵.
但是,在Russian site关于错误的GOTO声明的行为的一些惊人的发现(我不知道该说什么,我看不懂俄语). An English summary was posted at DosTips,行为进一步调查.
事实证明,(GOTO)2> NUL的行为几乎与EXIT / B相同,除了已经解析的代码块中的连接命令在有效返回之后仍然在CALLER的上下文中执行！
这是一个简短的例子,它演示了大部分的重点.
@echo off setlocal enableDelayedExpansion set "var=Parent Value" ( call :test echo This and the following line are not executed exit /b ) :break echo How did I get here^^!^^!^^!^^! exit /b :test setlocal disableDelayedExpansion set "var=Child Value" (goto) 2>nul & echo var=!var! & goto :break echo This line is not executed :break echo This line is not executed
– 输出 –
var=Parent Value How did I get here!!!!
>创建PrintHere.bat – 这是“nix这里的文件功能的仿真”
>创建一个RETURN.BAT utility,任何批处理“函数”可以方便地通过ENDLOCAL屏障返回任何值,几乎没有任何限制.该代码是jeb’s original idea的丰富版本.
现在我也可以添加异常处理列表:-)
该技术依赖于一个称为EXCEPTION.BAT的批处理实用程序来定义用于指定TRY / CATCH块的环境变量“宏”,以及抛出异常.
在可以实现TRY / CATCH块之前,必须使用以下命令定义宏：
call exception init
然后TRY / CATCH块用以下语法定义：
:calledRoutine setlocal %@Try% REM normal code goes here %@EndTry% :@Catch REM Exception handling code goes here :@EndCatch
可以随时通过以下方式抛出异常：
call exception throw errorNumber "messageString" "locationString"
当抛出异常时,它会使用(GOTO)2> NUL迭代地弹出CALL堆栈,直到它找到一个活动的TRY / CATCH,然后它分支到CATCH块并执行该代码.一系列异常属性变量可用于CATCH块：
> exception.Code – 数字异常代码
> exception.Msg – 异常消息字符串
> exception.Loc – 描述抛出异常的位置的字符串
> exception.Stack – 一个从CATCH块跟踪调用堆栈(或命令行,如果没有被捕获)的字符串,一直到异常来源.
如果异常被完全处理,则应该通过调用异常清除来清除异常,并且该脚本正常进行.如果异常没有被完全处理,那么一个新的异常可以抛出一个全新的异常.堆栈或旧的堆栈可以保存与
call exception rethrow errorNumber "messageString" "locationString"
如果未处理异常,则会打印一个“未处理的异常”消息,包括四个异常属性,所有批处理都将终止,并将控制返回到命令行上下文.
以下是使所有这些可能的代码 – 完整的文档嵌入在脚本中,并可以通过异常帮助或异常/？从命令行获取.
EXCEPTION.BAT
::EXCEPTION.BAT Version 1.4
::
:: Provides exception handling for Windows batch scripts.
::
:: Designed and written by Dave Benham,with important contributions from
:: DosTips users jeb and siberia-man
::
:: Full documentation is at the bottom of this script
::
:: History:
:: v1.4 2016-08-16 Improved detection of command line delayed expansion
:: using an original idea by jeb
:: v1.3 2015-12-12 Added paged help option via MORE
:: v1.2 2015-07-16 Use COMSPEC instead of OS to detect delayed expansion
:: v1.1 2015-07-03 Preserve ! in exception attributes when delayed expansion enabled
:: v1.0 2015-06-26 Initial versioned release with embedded documentation
::
@echo off
if "%~1" equ "/??" goto pagedHelp
if "%~1" equ "/?" goto help
if "%~1" equ "" goto help
shift /1 & goto %1
:throw errCode errMsg errLoc
set "exception.Stack="
:: Fall through to :rethrow
:rethrow errCode errMsg errLoc
setlocal disableDelayedExpansion
if not defined exception.Restart set "exception.Stack=[%~1:%~2] %exception.Stack%"
for /f "delims=" %%1 in ("%~1") do for /f "delims=" %%2 in ("%~2") do for /f "delims=" %%3 in ("%~3") do (
setlocal enableDelayedExpansion
for /l %%# in (1 1 10) do for /f "delims=" %%S in (" !exception.Stack!") do (
(goto) 2>NUL
setlocal enableDelayedExpansion
if "!!" equ "" (
endlocal
setlocal disableDelayedExpansion
call set "funcName=%%~0"
call set "batName=%%~f0"
if defined exception.Restart (set "exception.Restart=") else call set "exception.Stack=%%funcName%%%%S"
setlocal EnableDelayedExpansion
if !exception.Try! == !batName!:!funcName! (
endlocal
endlocal
set "exception.Code=%%1"
if "!!" equ "" (
call "%~f0" setDelayed
) else (
set "exception.Msg=%%2"
set "exception.Loc=%%3"
set "exception.Stack=%%S"
)
set "exception.Try="
(CALL )
goto :@Catch
)
) else (
for %%V in (Code Msg Loc Stack Try Restart) do set "exception.%%V="
if "^!^" equ "^!" (
call "%~f0" showDelayed
) else (
echo(
echo Unhandled batch exception:
echo Code = %%1
echo Msg = %%2
echo Loc = %%3
echo Stack=%%S
)
echo on
call "%~f0" Kill
)>&2
)
set exception.Restart=1
setlocal disableDelayedExpansion
call "%~f0" rethrow %1 %2 %3
)
:: Never reaches here
:init
set "@Try=call set exception.Try=%%~f0:%%~0"
set "@EndTry=set "exception.Try=" & goto :@endCatch"
:: Fall through to :clear
:clear
for %%V in (Code Msg Loc Stack Restart Try) do set "exception.%%V="
exit /b
:Kill - Cease all processing,ignoring any remaining cached commands
setlocal disableDelayedExpansion
if not exist "%temp%\Kill.Yes" call :buildYes
call :CtrlC <"%temp%\Kill.Yes" 1>nul 2>&1
:CtrlC
@cmd /c exit -1073741510
:buildYes - Establish a Yes file for the language used by the OS
pushd "%temp%"
set "yes="
copy nul Kill.Yes >nul
for /f "delims=(/ tokens=2" %%Y in (
'"copy /-y nul Kill.Yes <nul"'
) do if not defined yes set "yes=%%Y"
echo %yes%>Kill.Yes
popd
exit /b
:setDelayed
setLocal disableDelayedExpansion
for %%. in (.) do (
set "v2=%%2"
set "v3=%%3"
set "vS=%%S"
)
(
endlocal
set "exception.Msg=%v2:!=^!%"
set "exception.Loc=%v3:!=^!%"
set "exception.Stack=%vS:!=^!%"
)
exit /b
:showDelayed -
setLocal disableDelayedExpansion
for %%. in (.) do (
set "v2=%%2"
set "v3=%%3"
set "vS=%%S"
)
for /f "delims=" %%2 in ("%v2:!=^!%") do for /f "delims=" %%3 in ("%v3:!=^!%") do for /f "delims=" %%S in ("%vS:!=^!%") do (
endlocal
echo(
echo Unhandled batch exception:
echo Code = %%1
echo Msg = %%2
echo Loc = %%3
echo Stack=%%S
)
exit /b
:-?
:help
setlocal disableDelayedExpansion
for /f "delims=:" %%N in ('findstr /rbn ":::DOCUMENTATION:::" "%~f0"') do set "skip=%%N"
for /f "skip=%skip% tokens=1* delims=:" %%A in ('findstr /n "^" "%~f0"') do echo(%%B
exit /b
:-??
:pagedHelp
setlocal disableDelayedExpansion
for /f "delims=:" %%N in ('findstr /rbn ":::DOCUMENTATION:::" "%~f0"') do set "skip=%%N"
((for /f "skip=%skip% tokens=1* delims=:" %%A in ('findstr /n "^" "%~f0"') do @echo(%%B)|more /e) 2>nul
exit /b
:-v
:/v
:version
echo(
for /f "delims=:" %%A in ('findstr "^::EXCEPTION.BAT" "%~f0"') do echo %%A
exit /b
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:::DOCUMENTATION:::
EXCEPTION.BAT is a pure batch script utility that provides robust exception
handling within batch scripts. It enables code to be placed in TRY/CATCH blocks.
If no exception is thrown,then only code within the TRY block is executed.
If an exception is thrown,the batch CALL stack is popped repeatedly until it
reaches an active TRY block,at which point control is passed to the associated
CATCH block and normal processing resumes from that point. Code within a CATCH
block is ignored unless an exception is thrown.
An exception may be caught in a different script from where it was thrown.
If no active TRY is found after throwing an exception,then an unhandled
exception message is printed to stderr,all processing is terminated within the
current CMD shell,and control is returned to the shell command line.
TRY blocks are specified using macros. ObvIoUsly the macros must be defined
before they can be used. The TRY macros are defined using the following CALL
call exception init
Besides defining @Try and @EndTry,the init routine also explicitly clears any
residual exception that may have been left by prior processing.
A TRY/CATCH block is structured as follows:
%@Try%
REM any normal code goes here
%@EndTry%
:@Catch
REM exception handling code goes here
:@EndCatch
- Every TRY must have an associated CATCH.
- TRY/CATCH blocks cannot be nested.
- Any script or :labeled routine that uses TRY/CATCH must have at least one
SETLOCAL prior to the appearance of the first TRY.
- TRY/CATCH blocks use labels,so they should not be placed within parentheses.
It can be done,but the parentheses block is broken when control is passed to
the :@Catch or :@EndCatch label,and the code becomes difficult to interpret
and maintain.
- Any valid code can be used within a TRY or CATCH block,including CALL,GOTO,:labels,and balanced parentheses. However,GOTO cannot be used to leave a
TRY block. GOTO can only be used within a TRY block if the label appears
within the same TRY block.
- GOTO must never transfer control from outside TRY/CATCH to within a TRY or
CATCH block.
- CALL should not be used to call a label within a TRY or CATCH block.
- CALLed routines containing TRY/CATCH must have labels that are unique within
the script. This is generally good batch programming practice anyway.
It is OK for different scripts to share :label names.
- If a script or routine recursively CALLs itself and contains TRY/CATCH,then
it must not throw an exception until after execution of the first %@Try%
Exceptions are thrown by using
call exception throw Code Message Location
where
Code = The numeric code value for the exception.
Message = A description of the exception.
Location = A string that helps identify where the exception occurred.
Any value may be used. A good generic value is "%~f0[%~0]",which expands to the full path of the currently executing
script,followed by the currently executing routine name
within square brackets.
The Message and Location values must be quoted if they contain spaces or poison
characters like & | < >. The values must not contain additional internal quotes,and they must not contain a caret ^.
The following variables will be defined for use by the CATCH block:
exception.Code = the Code value
exception.Msg = the Message value
exception.Loc = the Location value
exception.Stack = traces the call stack from the CATCH block (or command line
if not caught),all the way to the exception.
If the exception is not caught,then all four values are printed as part of the
"unhandled exception" message,and the exception variables are not defined.
A CATCH block should always do ONE of the following at the end:
- If the exception has been handled and processing can continue,then clear the
exception definition by using
call exception clear
Clear should never be used within a Try block.
- If the exception has not been fully handled,then a new exception should be
thrown which can be caught by a higher level CATCH. You can throw a new
exception using the normal THROW,which will clear exception.Stack and any
higher CATCH will have no awareness of the original exception.
Alternatively,you may rethrow an exception and preserve the exeption stack
all the way to the original exception:
call exception rethrow Code Message Location
It is your choice as to whether you want to pass the original Code and/or
Message and/or Location. Either way,the stack will preserve all exceptions
if rethrow is used.
Rethrow should only be used within a CATCH block.
One last restriction - the full path to EXCEPTION.BAT must not include ! or ^.
This documentation can be accessed via the following commands
constant stream: exception /? OR exception help
paged via MORE: exception /?? OR exception pagedHelp
The version of this utility can be accessed via
exception /v OR exception version
EXCEPTION.BAT was designed and written by Dave Benham,with important
contributions from DosTips users jeb and siberia-man.
Development history can be traced at:
http://www.dostips.com/forum/viewtopic.PHP?f=3&t=6497
以下是测试EXCEPTION.BAT功能的脚本.该脚本递归调用自身7次.每个迭代都有两个CALL,一个到a：标签,表示正常的异常传播,另一个到演示脚本CALL的异常传播的脚本.
当从递归调用返回时,如果迭代计数是3的倍数(迭代3和6),则会抛出异常.
每个CALL都有自己的异常处理程序,通常会报告异常,然后重新抛出一个修改的异常.但如果迭代次数为5,那么处理异常并恢复正常处理.
@echo off
:: Main
setlocal enableDelayedExpansion
if not defined @Try call exception init
set /a cnt+=1
echo Main Iteration %cnt% - Calling :Sub
%@Try%
(
call :Sub
call echo Main Iteration %cnt% - :Sub returned %%errorlevel%%
)
%@EndTry%
:@Catch
setlocal enableDelayedExpansion
echo(
echo Main Iteration %cnt% - Exception detected:
echo Code = !exception.code!
echo Message = !exception.msg!
echo Location = !exception.loc!
echo Rethrowing modified exception
echo(
endlocal
call exception rethrow -%cnt% "Main Exception^!" "%~f0<%~0>"
:@EndCatch
echo Main Iteration %cnt% - Exit
exit /b %cnt%
:Sub
setlocal
echo :Sub Iteration %cnt% - Start
%@Try%
if %cnt% lss 7 (
echo :Sub Iteration %cnt% - Calling "%~f0"
call "%~f0"
%= Show any non-exception return code (demonstrate ERRORLEVEL is preserved if no exception) =%
call echo :Sub Iteration %cnt% - testException returned %%errorlevel%%
)
%= Throw an exception if the iteration count is a multiple of 3 =%
set /a "1/(cnt%%3)" 2>nul || (
echo Throwing exception
call exception throw -%cnt% "Divide by 0 exception^!" "%~f0<%~0>"
)
%@EndTry%
:@Catch
setlocal enableDelayedExpansion
echo(
echo :Sub Iteration %cnt% - Exception detected:
echo Code = !exception.code!
echo Message = !exception.msg!
echo Location = !exception.loc!
endlocal
%= Handle the exception if iteration count is a multiple of 5,else rethrow it with new properties =%
set /a "1/(cnt%%5)" 2>nul && (
echo Rethrowing modified exception
echo(
call exception rethrow -%cnt% ":Sub Exception^!" "%~f0<%~0>"
) || (
call exception clear
echo Exception handled
echo(
)
:@EndCatch
echo :Sub Iteration %cnt% - Exit
exit /b %cnt%
– 输出 –
Main Iteration 1 - Calling :Sub :Sub Iteration 1 - Start :Sub Iteration 1 - Calling "C:\test\testException.bat" Main Iteration 2 - Calling :Sub :Sub Iteration 2 - Start :Sub Iteration 2 - Calling "C:\test\testException.bat" Main Iteration 3 - Calling :Sub :Sub Iteration 3 - Start :Sub Iteration 3 - Calling "C:\test\testException.bat" Main Iteration 4 - Calling :Sub :Sub Iteration 4 - Start :Sub Iteration 4 - Calling "C:\test\testException.bat" Main Iteration 5 - Calling :Sub :Sub Iteration 5 - Start :Sub Iteration 5 - Calling "C:\test\testException.bat" Main Iteration 6 - Calling :Sub :Sub Iteration 6 - Start :Sub Iteration 6 - Calling "C:\test\testException.bat" Main Iteration 7 - Calling :Sub :Sub Iteration 7 - Start :Sub Iteration 7 - Exit Main Iteration 7 - :Sub returned 7 Main Iteration 7 - Exit :Sub Iteration 6 - testException returned 7 Throwing exception :Sub Iteration 6 - Exception detected: Code = -6 Message = Divide by 0 exception! Location = C:\test\testException.bat<:Sub> Rethrowing modified exception Main Iteration 6 - Exception detected: Code = -6 Message = :Sub Exception! Location = C:\test\testException.bat<:Sub> Rethrowing modified exception :Sub Iteration 5 - Exception detected: Code = -6 Message = Main Exception! Location = C:\test\testException.bat<C:\test\testException.bat> Exception handled :Sub Iteration 5 - Exit Main Iteration 5 - :Sub returned 5 Main Iteration 5 - Exit :Sub Iteration 4 - testException returned 5 :Sub Iteration 4 - Exit Main Iteration 4 - :Sub returned 4 Main Iteration 4 - Exit :Sub Iteration 3 - testException returned 4 Throwing exception :Sub Iteration 3 - Exception detected: Code = -3 Message = Divide by 0 exception! Location = C:\test\testException.bat<:Sub> Rethrowing modified exception Main Iteration 3 - Exception detected: Code = -3 Message = :Sub Exception! Location = C:\test\testException.bat<:Sub> Rethrowing modified exception :Sub Iteration 2 - Exception detected: Code = -3 Message = Main Exception! Location = C:\test\testException.bat<C:\test\testException.bat> Rethrowing modified exception Main Iteration 2 - Exception detected: Code = -2 Message = :Sub Exception! Location = C:\test\testException.bat<:Sub> Rethrowing modified exception :Sub Iteration 1 - Exception detected: Code = -2 Message = Main Exception! Location = C:\test\testException.bat<C:\test\testException.bat> Rethrowing modified exception Main Iteration 1 - Exception detected: Code = -1 Message = :Sub Exception! Location = C:\test\testException.bat<:Sub> Rethrowing modified exception Unhandled batch exception: Code = -1 Msg = Main Exception! Loc = C:\test\testException.bat<testException> Stack= testException [-1:Main Exception!] :Sub [-1::Sub Exception!] C:\test\testException.bat [-2:Main Exception!] :Sub [-2::Sub Exception!] C:\test\testException.bat [-3:Main Exception!] :Sub [-3::Sub Exception!] [-3:Divide by 0 exception!]
最后,这里是一系列简单的脚本,显示了即使中间脚本对它们没有任何知识也可以有效地使用异常！
开始使用一个简单的分割脚本实用程序,分割两个数字并打印结果：
divide.bat
:: divide.bat numerator divisor @echo off setlocal set /a result=%1 / %2 2>nul || call exception throw -100 "Division exception" "divide.bat" echo %1 / %2 = %result% exit /b
请注意,如果脚本检测到错误,脚本会引发异常,但是它不会捕获异常.
现在我将编写一个对批处理异常完全天真的分割测试工具.
testDivide.bat
@echo off for /l %%N in (4 -1 0) do call divide 12 %%N echo Finished successfully!
–OUTPUT–
C:\test>testDivide 12 / 4 = 3 12 / 3 = 4 12 / 2 = 6 12 / 1 = 12 Unhandled batch exception: Code = -100 Msg = Division exception Loc = divide.bat Stack= testDivide divide [-100:Division exception]
请注意,由于没有处理由divide.bat引发的异常,最终的ECHO将不会执行.
最后我会写一个主脚本,调用天真的testDivide并正确处理异常：
master.bat
@echo off setlocal call exception init %@Try% call testDivide %@EndTry% :@Catch echo %exception.Msg% detected and handled call exception clear :@EndCatch echo Finished Successfully!
– 输出 –
C:\test>master 12 / 4 = 3 12 / 3 = 4 12 / 2 = 6 12 / 1 = 12 Division exception detected and handled Finished Successfully!
主脚本能够成功地捕获由divide.bat引发的异常,即使它必须通过testDivide.bat,它不了解异常.很酷 ：-)
现在,这并不是所有与错误处理有关的事情的灵丹妙药：
>有许多语法和代码布局限制,在内置文档中已经完全描述.但没有什么太糟糕.
>没有办法自动将所有错误视为例外.所有异常必须由代码显式抛出.这可能是一件好事,因为错误报告是按惯例处理的 – 没有严格的规则.一些程序不符合惯例.例如,HELP ValidCommand返回ERRORLEVEL 1,这通常意味着一个错误,而HELP InvalidCommand返回ERRORLEVEL 0,这意味着成功.
>此批处理异常技术无法捕获并处理致命的运行时错误.例如GOTO：NonExistentLabel仍然会立即终止所有批处理,没有任何机会来捕获错误.
您可以在http://www.dostips.com/forum/viewtopic.php?f=3&t=6497跟随EXCEPTION.BAT的发展.将来会发布任何未来的发展.我可能不会更新此StackOverflow文章.
