empty/not empty EL表达式使用注意

description The server encountered an internal error () that prevented it from fulfilling this request.

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.18 logs.

今天在用EL表达式时发现empty不太好使出现如上的错误，但在同样的代码在他人机器好使，于是查了一下发现反应此问题还挺多的，有许多人反映跟jdk和tomcat的版本相关，无意间在网上发现了这篇贴子的回帖解决了此问题（将not empty(xx)改为not empty (xx),即是在empty与()之间加上空格，具体看帖子的绿色字体的回帖解释），在此分享一下：

Details

Type: Bug
Status: Closed
Priority: Blocker
Resolution:Fixed
Affects Version/s:1.1
Fix Version/s:1.1.2
Component/s:Web Interface
Labels:
None
Environment:
Windows XP SP3 FR
java (JDK) "1.6.0_07"
apache tomcat "6.0.18"
activation-1.1.jar
mail-1.4.jar
derby-10.1.3.1.jar

Number of attachments :
3

Description

　　After installing as Wiki said, as a tomcat WAR, i get parsing error in some JSP/TAG code.

　　Some examples :

　　org.apache.jasper.JasperException: /WEB-INF/jsp/components/companyLogo.jsp(22,0) "${!empty(organisationLogo)}" contient 　　　　　　d'incorrecte(s) expression(s): javax.el.ELException: Function ':empty' not found
　　org.apache.jasper.JasperException: /WEB-INF/tags/currentWWUrl.tag(29,0) "${!empty(action) && !empty(namespace)}" contient 　　　　　　d'incorrecte(s) expression(s): javax.el.ELException: Function ':empty' not found

　　I've added logs as attachments.

　　The workaround is very simple :
　　replace EL exepressions containing "empty(" with "empty (", and "not(" with "not (" as EL expression requires.

　　This is a VERY strange error since i've successufully setup Archiva on my profesionnal server, and i got these error on two distinct personnal 　　systems.

　　I'll check the professionnal/personnal system differences.

Attachments

catalina.2008-08-10.log
10/Aug/08 1:06 PM
73 kB
localhost.2008-08-10.log
10/Aug/08 1:06 PM
10 kB
MRM-905.patch
15/Aug/08 5:08 AM
19 kB

Activity

Maria Odea Ching added a comment - 14/Aug/08 1:07 AM - edited

　　I couldn't replicate this on trunk (-r685734), with the following environment:

ubuntu linux
java version "1.5.0_11"
tomcat 6.0.14
activation-1.1.jar, derby-10.1.3.1.jar and mail-1.4.jar

Maria Odea Ching added a comment - 14/Aug/08 4:39 AM

　　I was now able to replicate this issue when I deployed Archiva to Tomcat 6.0.18. I don't see the error in 5.5.17 and 6.0.14 though.. there must be a conflict with the EL lib included in 　　　　　6.0.18. I'll try your suggestion above to fix this, thanks!

Fabrice Daugan added a comment - 14/Aug/08 6:35 AM

　　Yes!
　　that's what i just found during the professionnal/personnal system differences.
　　Same JDK, but 6.0.14 Tomcat version.

Roman Legat added a comment - 14/Aug/08 10:08 AM - edited

　　Same here.
　　My configuration:
　　Ubuntu Server 8.04
　　java 1.6.0_06
　　tomcat 6.0.18
　　Archiva 1.1.1 deployed as a .war

　　Stacktrace starts with:
　　org.apache.jasper.JasperException: /WEB-INF/jsp/admin/repositories.jsp(53,0) "${empty(managedRepositories)}" contains invalid expression(s): javax.el.ELException: Function ':empty' 　　　not found
　　org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)

　　The suggested fix works for me. Fabrice, you made my day!
　　I ran
　　sudo sed -i.BAK -e "s/empty(/empty (/g" *.jsp*
　　sudo sed -i.BAK -e "s/not(/not (/g" *.jsp*
　　over the jsp folder and it works like a charm.

　　So the question is, is "empty(" invalid or not. There have been quite some changes in jasper between
　　6.0.14 and 6.0.18 (http://tomcat.apache.org/tomcat-6.0-doc/changelog.html), but i'm really not into the jsp stuff, so I couldn't tell...

Fabrice Daugan added a comment - 14/Aug/08 12:59 PM - edited

　　Also, i think there are some common code with Continuum, since the same error (but non blocker) occurs in the header.

　　As said in the EL specification (simplified version)

　　http://java.sun.com/products/jsp/syntax/2.0/syntaxref207.html

　　${ Expression }
　　Expression = {(UnaryOp Expression) | Value }
　　UnaryOp = {'-' | ! | not | empty }
　　Value = {ValuePrefix | (Value ValueSuffix) }
　　ValuePrefix = {Literal | '('Expression')' | ImplicitObject | Java language identifier}
　　ValueSuffix = { . Identifier | '['Expression']'}
　　Literal = {StringLiteral | null}
　　StringLiteral = {'[^(' | \) | \' | \\]+' | "[^(" | \) | \" | \\]+"}

　　If we read well the Tomcat error is right : since the grammar does not validate :
　　empty("hello")
　　but validate :
　　empty ("hello")

Maria Odea Ching added a comment - 14/Aug/08 8:20 PM - edited

　　Ok, thanks a lot for both of your help on this! Would either of you like or is interested to submit a patch for the fix?

Fabrice Daugan added a comment - 15/Aug/08 5:08 AM

　　The patch did from the revision 686186.
　　The root path of this patch is http://svn.apache.org/repos/asf/archiva/trunk/archiva-modules/archiva-web/archiva-webapp

Maria Odea Ching added a comment - 17/Aug/08 8:46 PM

　　Thanks for the patch Fabrice! I already applied it in trunk -r686665 and tested it with Tomcat versions 5.5.17, 6.0.14 and 6.0.18. It works nicely

empty/not empty EL表达式使用注意

HTTP Status 500 -

EL Expression failed with empty/not functions

Details

Description

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