Chapter 5. Dumping classes during load-time weaving

Table of Contents

Introduction
Configuring bytecode dumping in load-time weaving
LTW Dump Examples

Introduction

Very rarely problems may be encountered with classes that have been load-time woven. Symptoms will include incorrect program function or a Java exception such as java.lang.VerifyError. In these situations it's most helpful to include the offending class in the bug report. When using load-time weaving the woven classes are in memory only so to save them to disk configure META-INF/aop.xml to dump the classes (by default to an _ajdump subdirectory of the current working directory). Also if the input class file is not available (e.g. it is a generated proxy or has already been instrumented by another agent) you can configure the weaver to dump the input classes as well.

Configuring bytecode dumping in load-time weaving

For details of how to configure byte-code dumping, see the AspectJ Development Environment Guide section on Configuring Load-time Weaving. Following is a simple example.

LTW Dump Examples

The following META-INF/aop.xml will weave classes in the com.foo package (and subpackages) but not CGLIB generated classes in the com.foo.bar package (and subpackages). It will also ensure all woven byte-code is dumped both before and after weaving.

	<aspectj>
		<aspects>
			<aspect name="ataspectj.EmptyAspect"/>
		</aspects>
	    <weaver options="-verbose -debug">
	        <dump within="com.foo.bar..*" beforeandafter="true"/> 
    	    <include within="com.foo..*"/>
        	<exclude within="com.foo.bar..*CGLIB*"/>
		</weaver>
	</aspectj>
			

You should see messages similar to this:

[WeavingURLClassLoader] info AspectJ Weaver Version 1.5.3 built on Thursday Oct 26, 2006 at 17:22:31 GMT
[WeavingURLClassLoader] info register classloader org.aspectj.weaver.loadtime.WeavingURLClassLoader
[WeavingURLClassLoader] info using configuration /C:/tempMETA-INF/aop.xml
[WeavingURLClassLoader] info register aspect ataspectj.EmptyAspect
[WeavingURLClassLoader] debug not weaving 'com.foo.bar.Test$$EnhancerByCGLIB$$12345'
[WeavingURLClassLoader] debug weaving 'com.foo.bar.Test'
			

On disk you would find the following files:

	_ajdump/_before/com/foo/bar/Test.class
	_ajdump/com/foo/bar/Test.class