Annotation Interface EnableLoadTimeWeaving
LoadTimeWeaver
for this application context, available as
a bean with the name "loadTimeWeaver", similar to the <context:load-time-weaver>
element in Spring XML.
To be used on @Configuration
classes;
the simplest possible example of which follows:
@Configuration @EnableLoadTimeWeaving public class AppConfig { // application-specific @Bean definitions ... }The example above is equivalent to the following Spring XML configuration:
<beans> <context:load-time-weaver/> <!-- application-specific <bean> definitions --> </beans>
The LoadTimeWeaverAware
interface
Any bean that implements the LoadTimeWeaverAware
interface
will then receive the LoadTimeWeaver
reference automatically; for example,
Spring's JPA bootstrap support.
Customizing the LoadTimeWeaver
The default weaver is determined automatically: see DefaultContextLoadTimeWeaver
.
To customize the weaver used, the @Configuration
class annotated with
@EnableLoadTimeWeaving
may also implement the LoadTimeWeavingConfigurer
interface and return a custom LoadTimeWeaver
instance through the
#getLoadTimeWeaver
method:
@Configuration @EnableLoadTimeWeaving public class AppConfig implements LoadTimeWeavingConfigurer { @Override public LoadTimeWeaver getLoadTimeWeaver() { MyLoadTimeWeaver ltw = new MyLoadTimeWeaver(); ltw.addClassTransformer(myClassFileTransformer); // ... return ltw; } }
The example above can be compared to the following Spring XML configuration:
<beans> <context:load-time-weaver weaverClass="com.acme.MyLoadTimeWeaver"/> </beans>
The code example differs from the XML example in that it actually instantiates the
MyLoadTimeWeaver
type, meaning that it can also configure the instance, e.g.
calling the #addClassTransformer
method. This demonstrates how the code-based
configuration approach is more flexible through direct programmatic access.
Enabling AspectJ-based weaving
AspectJ load-time weaving may be enabled with theaspectjWeaving()
attribute, which will cause the AspectJ class transformer to
be registered through LoadTimeWeaver.addTransformer(java.lang.instrument.ClassFileTransformer)
. AspectJ weaving will be
activated by default if a "META-INF/aop.xml" resource is present on the classpath.
Example:
@Configuration @EnableLoadTimeWeaving(aspectjWeaving=ENABLED) public class AppConfig { }
The example above can be compared to the following Spring XML configuration:
<beans> <context:load-time-weaver aspectj-weaving="on"/> </beans>
The two examples are equivalent with one significant exception: in the XML case,
the functionality of <context:spring-configured>
is implicitly enabled when
aspectj-weaving
is "on". This does not occur when using
@EnableLoadTimeWeaving(aspectjWeaving=ENABLED)
. Instead you must explicitly add
@EnableSpringConfigured
(included in the spring-aspects
module)
- Since:
- 3.1
- Author:
- Chris Beams
- See Also:
-
LoadTimeWeaver
DefaultContextLoadTimeWeaver
ClassPreProcessorAgentAdapter
-
Nested Class Summary
Modifier and TypeClassDescriptionstatic enum
AspectJ weaving enablement options. -
Optional Element Summary
Modifier and TypeOptional ElementDescriptionWhether AspectJ weaving should be enabled.
-
Element Details
-
aspectjWeaving
EnableLoadTimeWeaving.AspectJWeaving aspectjWeavingWhether AspectJ weaving should be enabled.- Default:
- AUTODETECT
-