John,
I've looked into doing something like this specifically for
ActionBeans. In my case, I wanted to use various Spring annotations
(security, transaction) on my ActionBean event handler methods. In a
nutshell, I extended Stripe's NameBasedActionResolver to fetch
ActionBean instances from Spring.
Some of the issues I encountered:
* For Spring-managed ActionBeans, you can't use JDK dynamic proxies,
because DP's require an interface to hide behind. Instead, I used
CGLib proxies. With CGLib proxies, the ActionBean needs to be
registered with Stripes twice; Once under the original class name, and
again under the CGLib descendant class name e.g.
- com.foo.ExampleActionBean and...
- com.foo.ExampleActionBean$$EnhancerByCGLIB$$515e0936
* Creating explicit Spring XML config for lots of objects is a real
bitch - and if you're a Stripes fan you'll probably want to stay away
from that. My approach dynamically created Spring-managed ActionBeans
in the Spring context. This worked fine until I switched to using
Spring's WebApplicationContext. The Spring WebApplicationContext
doesn't allow you to programmatically define beans. Bah.
In the end I shelved this work because I was doing fine without those
annotations at the ActionBean level. Below is my original
implementation of a Spring ActionResolver. Hope this helps.
Chris.
/**
* Instantiates Stripes ActionBeans by programmaticially defining a
Spring bean.
* This is preferable to defining every Stripes ActionBean in the
application
* context XML config. The main reason for doing this is to leverage
Spring
* interceptors for things like security. Note that because action
beans are not
* usually accessed via interfaces, CGLib proxies must be used
instead of JDK
* dynamic proxies. To do this, must have the following config in
your Spring
* application context XML:
* <aop:config proxy-target-class="true"/>.
* Beware that CGLib proxies have certain limitations (e.g. cannot
proxy methods
* marked as final).
*
* @author cherro
*/
public class SpringActionResolver extends NameBasedActionResolver {
/** Tracks the ActionBeans that have already been defined in
Spring. */
private Set<String> processedBeanNames = new HashSet<String>();
/** [EMAIL PROTECTED] */
@Override
protected ActionBean makeNewActionBean(
Class<? extends ActionBean> type,
ActionBeanContext actionBeanContext)
throws Exception {
final String beanName = type.getName();
if (!processedBeanNames.contains(beanName)) {
GenericApplicationContext springContext =
SpringUtil.getInstance().getContext();
BeanDefinition beanDefinition = new
RootBeanDefinition(type);
beanDefinition.setScope(BeanDefinition.SCOPE_PROTOTYPE);
springContext.registerBeanDefinition(beanName,
beanDefinition);
ActionBean proxied =
(ActionBean) SpringUtil.getInstance().getContext()
.getBean(beanName, type);
// The CGLib proxy has a different class name (because it
is a
// subtype of the proxied class). So, we need to register
the new
// class in order to configure its event mappings.
super.addActionBean(proxied.getClass());
processedBeanNames.add(beanName);
return proxied;
} else {
return (ActionBean) SpringUtil.getInstance().getContext()
.getBean(beanName, type);
}
}
}
On May 15, 2008, at 10:47 AM, Newman, John W wrote:
Hi,
I’d like for my application specific extensions to stripes (type
converters, interceptors, even action beans, etc) to be pulled out
of the spring context. I’ve managed to do this somewhat by
providing my own Configuration, but the implementation is far from
ideal. So I was thinking everywhere stripes calls
class.newInstance(), could that be replaced by
instantiator.newInstance(), where instantiator is a configurable
component to provide new instances of a given class...
For example,
interface Instantiator {
<T> T newInstance(Class<T> clazz) throws InstantiationException,
IllegalAccessException;
}
class DefaultInstantiator implements Instantiator {
public <T> T newInstance(Class<T> clazz) throws
InstantiationException,
IllegalAccessException {
return clazz.newInstance();
}
}
class SpringInstantiator extends DefaultInstantiator {
@Override
public <T> T newInstance(Class<T> clazz) throws
InstantiationException,
IllegalAccessException {
T bean = SpringUtil.getInstance().getBean(clazz);
if (bean != null) {
return bean;
}
return super.newInstance(clazz);
}
}
That would offer much better integration between stripes and
spring / other DI frameworks. This could also eliminate the
@SpringBean annotation and allow action beans to use normal setter
injection. Thoughts?
-John
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