如何使用 AspectJ 和 Tomcat 配置加载时编织？

Question

I tried to configure load-time weaving (for doing profiling with Perf4J) in the next way:

1) I added aop.xml to META-INF folder. When deployed, META-INF is placed in the artifact root directory (ie MyAppDeployed/META-INF ).

2) I put aspectjrt-1.6.1.jar , aspectjweaver-1.6.1.jar , commons-jexl-1.1.jar , commons-logging.jar to the Tomcat/lib folder (at first I tried MyAppDeployed/WEB-INF/libs but it also didn't work).

3) I added -javaagent:C:\apache-tomcat-6.0.33\lib\aspectjweaver-1.6.1.jar to VM options when starting Tomcat.

4) My aop.xml :

<!DOCTYPE aspectj PUBLIC "-//AspectJ//DTD//EN" "http://www.eclipse.org/aspectj/dtd/aspectj.dtd">

<aspectj>

    <aspects>
        <aspect name="org.perf4j.log4j.aop.TimingAspect"/>
    </aspects>

    <weaver options="-verbose -showWeaveInfo">           
        <include within="com.mypackages.MyClass"/>
    </weaver>
</aspectj>

I don't see any signs that load-time weaving happens. Neither error-reports nor necessary results. The only error message I have is:

Error occurred during initialization of VM
agent library failed to init: instrument
Error opening zip file: C:\apache-tomcat-6.0.33\lib\wrong-jar.jar

in a case when I do a mistake in a aspectjweaver-1.6.1.jar name when specify a javaagent parameter. If it's written correctly - no error messages are printed.

Any ideas, what am I doing wrong?

PS I use Java 5, and I tried the same things with 1.5.4 version of the aspectj with exactly the same results.

Answer 1

If you want to use load time weaving, you can first compile your classes with javac as usual then compile your aspect(s) with (i)ajc . You can do this with an ant task like below

<target name="compile-aspect">
    <iajc source="1.6" target="1.6" showweaveinfo="true" verbose="true" outxml="true" debug="true" outjar="${dist.dir}/myaspect.jar">
            <argfiles>
                    <pathelement location="${src.dir}/sources.lst"/>
            </argfiles>
            <classpath>
                    <path refid="master-classpath" />
            </classpath>
    </iajc>
</target>

It is enough to have aspectjrt.jar in the classpath ( "master-classpath" ) during compilation.

Since all of my Java classes in ${src.dir} , I give a source list to iajc. In source list there is only one line.

sources.lst

com/xx/yy/zz/LoggingAspect.java

I set some of iajc task's attributes as follows

outxml="true"
outjar="jar_file_name"

When I run compile-aspect task I have a jar jar_file_name.jar file contains

META-INF/MANIFEST.MF
com/xx/yy/zz/LoggingAspect.class
META-INF/aop-ajc.xml

And finally add the *jar_file_name.jar* to your web application's WEB-INF/lib folder.

Then start Tomcat with -javaagents:/path_to_aspectjweaver.jar as you did before.

When I put the aop.xml (or aop-ajc.xml) in META-INF under the war file directly it doesn't work. This way (I mean seperating aspect classes into a jar) just works fine for me.

Hope this helps.

Answer 2

I was trying to solve the same issue in Tomcat. In addition to -javaagent option, you need to make sure the aop.xml must be under the WEB-INF/classes/META-INF dir. This made the difference for me.