Chapter 5. Dumping classes during load-time weaving
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## Chapter 5. Dumping classes during load-time weaving

## 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

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