Regular Expressions in JMeter

JMeter includes the pattern matching software Apache Jakarta ORO.

There is some documentation for this on the Jakarta web-site.

A summary of the pattern matching characters can be found at http://jakarta.apache.org/oro/api/org/apache/oro/text/regex/package-summary.html51Testing软件测试网fKb[4_9J~a

There is also documentation on an older incarnation of the product at OROMatcher User's guide, which might prove useful.51Testing软件测试网T@v!C*g%^K?

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Overview

The pattern matching is very similar to the pattern matching in Perl. A full installation of Perl will include plenty of documentation on regular expressions - look for perlrequick, perlretut, perlre, perlreref. O'Reilly sell a book called "Mastering Regular Expressions" by Jeffrey Friedl which will tell you all you need to know (and a lot more) about regular expressions.51Testing软件测试网p:}dh%F,]:B S4Z*l9yJ

There are also a couple of sample chapters available on their web-site covering REs in Java and .NET, and the Java chapter has a section on ORO (PDF)- worth a look.51Testing软件测试网\ wYC0N sGPa#{

It is worth stressing the difference between "contains" and "matches", as used on the Response Assertion test element:

• "contains" means that the regular expression matched at least some part of the target, so 'alphabet' "contains" 'ph.b.' because the regular expression matches the substring 'phabe'.

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• "matches" means that the regular expression matched the whole target. So 'alphabet' is "matched" by 'al.*t'. In this case, it is equivalent to wrapping the regular expression in ^ and $, viz '^al.*t$'. However, this is not always the case. For example, the regular expression 'alp|.lp.*' is "contained" in 'alphabet', but does not match 'alphabet'.51Testing软件测试网n`-rR4l#H

Why? Because when the pattern matcher finds the sequence 'alp' in 'alphabet', it stops trying any other combinations - and 'alp' is not the same as 'alphabet', as it does not include 'habet'.

Note: unlike Perl, there is no need to (i.e. do not) enclose the regular expression in //. So how does one use the Perl modifiers ismx etc if there is no trailing /? The solution is to use Perl5 extended regular expressions, i.e. /abc/i becomes (?i)abc

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Links to regex resources

These resources are not for Jakarta ORO specifically, but are helpful in understanding Regexes in general.

• http://www.regular-expressions.info/tutorial.html

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• http://tlc.perlarchive.com/articles/perl/pm0001_perlretut.shtml51Testing软件测试网*H3Xr
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• http://www.visibone.com/regular-expressions/ - quick reference

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• http://www.regexlib.com/ - regular expressions library51Testing软件测试网8?;{
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• http://java.sun.com/docs/books/tutorial/extra/regex/index.html - Tutorial on java.util.regex51Testing软件测试网&nC:S| o9L8T

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Links to Regex Testers

• http://jakarta.apache.org/oro/demo.html - Java applet using Jakarta ORO51Testing软件测试网"|\JW)jFo

Note that the following testers use engines which may work slightly differently from the Jakarta-ORO (the one currently used by JMeter). However, a lot of regexes will work the same in all the tools.

• http://jakarta.apache.org/regexp/applet.html - online Jakarta regexp package tester

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• http://weitz.de/regex-coach/ - easy to use regex tester (Linux and Windows, Perl-like expressions)51Testing软件测试网6D"a+Qs)g@0e9H

• http://jregexptester.sourceforge.net/index.html - Java Swing (requires JVM 1.4 or above, presumably uses java.util.regex)51Testing软件测试网,[P+{ _,X[gL!pv%U

• http://www.fileformat.info/tool/regex.htm - online java.util.regex tester

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• http://royo.is-a-geek.com/iserializable/regulator/ - the Regulator (Windows only, .NET regexes)

  
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Examples

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Extract single string

Suppose you want to match the following portion of a web-page: name="file" value="readme.txt" and you want to extract readme.txt.51Testing软件测试网 Iy'{7lJ*R#M;W#z N#V7V

A suitable reqular expression would be:51Testing软件测试网4ba6h2LFq[^

name="file" value="(.+?)"

The special characters above are:

• ( and ) - these enclose the portion of the match string to be returned51Testing软件测试网:{a IMl a8s

• . - match any character. + - one or more times. ? - don't be greedy, i.e. stop when first match succeeds51Testing软件测试网&C,k4WL$@*X6Ke

Note: without the ?, the .+ would continue past the first " until it found the last possible " - probably not what was intended.51Testing软件测试网#H @0~'D1R#E6k7G!k

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Extract multiple strings

Suppose you want to match the following portion of a web-page: name="file.name" value="readme.txt" and you want to extract file.name and readme.txt.

A suitable reqular expression would be:51Testing软件测试网UPD Xf6T7\k l

name="(.+?)" value="(.+?)"

This would create 2 groups, which could be used in the JMeter Regular Expression Extractor template as $1$ and $2$.51Testing软件测试网$\x1@1hz G

The JMeter Regex Extractor saves the values of the groups in additional variables.51Testing软件测试网 p"q1bh
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For example, assume:51Testing软件测试网s4e l7_{U:A&XB]$~5N

• Reference Name: is MYREF

• Regex: name="(.+?)" value="(.+?)"

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• Template: $1$$2$

The following variables would be set:51Testing软件测试网-lUdHE!D`

• MYREF: file.namereadme.txt
• MYREF_g0: name="file.name" value="readme.txt"
• MYREF_g1: file.name
• MYREF_g2: readme.txt

These variables can be referred to later on in the JMeter test plan, as ${MYREF}, ${MYREF_g1} etc51Testing软件测试网;O;M#Y(Ju:_ F `;T*`8gC l