It's no bug, it's a feature...
The policy for model access (e.g. property calls) via expression
evaluation is fail silent. It would cause tons of exceptions if ognl
expression evaluation / property access would not swallow them.
The business logic access methods of your action, such as prepare(),
execute(), save(), delete()... _do_ pop any unhadled exception to the
upper layer, which is perfectly suitable for transaction handling.
Most likely, you are doing business logic calls in your model access
domain and you should think of moving any call with the possibility to get
service relevant exceptions to the described business logic domain access
methods.
Regards,
Rene
Am Do, 16.08.2007, 17:01, schrieb Ruimo Uno:
> Hi,
>
> I have submitted this to user list a few hours ago but finally, I
> found the root cause of this issue. So, here I report it to dev list.
> If an exception is thrown while OGNL expression evaluation such as in
> the following scenario:
>
> XXXAction
> public String getMessage() {
> throw new NullPointerException();
> }
>
> XXX.jsp
> <s:property value="message"/>
>
> The exception is wrapped in an OgnlException and re-thrown. It is
> caught in com.opensymphony.xwork2.util.CompoundRootAccessor.getProperty()
> and wrapped in a XWorkException() and re-thrown.
>
> } catch (OgnlException e) {
> if (e.getReason() != null) {
> final String msg = "Caught an Ognl exception while getting
> property " + name;
> throw new XWorkException(msg, e);
> }
> } catch (IntrospectionException e) {
>
> Finally, it is caught in
> com.opensymphony.xwork2.util.OgnlValueStack.findValue(String, Class)
> and swallowed.
>
> } catch (Exception e) {
> logLookupFailure(expr, e);
>
> return findInContext(expr);
> } finally {
>
> As a result, the upper layer does not receive any exception. So, no
> exception handler is invoked even if it is registered. Moreover, in
> 'open session in view' pattern, since the upper layer are not notified
> any error, the transaction is wrongly committed and it causes serious
> problem.
>
> I tried to add a catch clause for RuntimeException:
>
> } catch (RuntimeException e) {
> logLookupFailure(expr, e);
> throw e;
> } catch (Exception e) {
> logLookupFailure(expr, e);
>
> return findInContext(expr);
> } finally {
>
> Yes, the exception is successfully thrown to the upper layer with this
> code change. However, Struts shows 'java.io.IOException: Stream
> closed:' on the browser. This message seems a bit confusing. and
> difficult to realize what is actually happening (NPE is thrown). Does
> anybody have better solution on this?
>
> Thanks,
>
> --
> Ruimo Uno
> (Shisei Hanai)
>
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>
--
Rene Gielen | http://it-neering.net/
Aachen | PGP-ID: BECB785A
Germany | gielen at it-neering.net
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