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POSpring - Intercepting bean creation and injecting custom proxy
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copied!<p>I have a <code>@Controller</code> with <code>@Autowired</code> fields and handler methods that I want to annotate with custom annotations. </p> <p>For example,</p> <pre><code>@Controller public class MyController{ @Autowired public MyDao myDao; @RequestMapping("/home") @OnlyIfXYZ public String onlyForXYZ() { // do something return "xyz"; } } </code></pre> <p>Where <code>@OnlyIfXYZ</code> is an example of a custom annotation. I was thinking I would intercept the Controller bean creation, pass my own CGLIB proxy on which Spring can then set properties, like the autowired field.</p> <p>I tried using a <code>InstantiationAwareBeanPostProcessor</code> but that solution doesn't work great because <code>postProcessBeforeInstantiation()</code> short-circuits the rest of the process. I tried with <code>postProcessAfterInitialization()</code>, like below</p> <pre><code>public class MyProcessor implements BeanPostProcessor { @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { // Here the bean autowired fields are already set return bean; } @Override public Object postProcessAfterInitialization(Object aBean, String aBeanName) throws BeansException { Class<?> clazz = aBean.getClass(); // only for Controllers, possibly only those with my custom annotation on them if (!clazz.isAnnotationPresent(Controller.class)) return aBean; Object proxy = Enhancer.create(clazz, new MyMethodInterceptor()); Field[] fields = clazz.getDeclaredFields(); for (Field field : fields) { field.setAccessible(true); try { // get the field and copy it over to the proxy Object objectToCopy = field.get(aBean); field.set(proxy, objectToCopy); } catch (IllegalArgumentException | IllegalAccessException e) { return aBean; } } return proxy; } } </code></pre> <p>This solution uses reflection to copy over all the fields of the target bean to the proxy bean (kind of hacky for my taste). But I don't have access to the <code>HttpServletRequest</code> and <code>HttpServletResponse</code> objects if those aren't arguments in the method I'm intercepting.</p> <p>Is there another callback I can inject into Spring bean creation logic to inject my own Proxy Controller before Spring populates its properties? <strong>I need to be able to access the <code>HttpServletRequest</code> and <code>HttpServletResponse</code> objects regardless of if the Controller handler method has it in its definition, ie. as arguments.</strong></p> <p><strong>N.B</strong> The <code>@Autowired</code> field is also a proxy, it is annotated with <code>@Transactional</code> so Spring proxies it up.</p> <p><strong>EDIT:</strong> The AOP solution works nicely for intercepting the method invocation, but I can't find a way to access the <code>HttpServletRequest</code> and <code>HttpServletResponse</code> objects, if they aren't already method arguments.</p> <p>I'm probably going to end up using HandlerInterceptorAdapter, but I was hoping I can do it with OOP so as to not add the overhead to methods that don't need it.</p>

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