Ramki Technical Blog

This is Fourth  part of CDI discussion.Please visit   part one ,  part two  and    part three Interceptors Interceptors is one feature of CDI. Using this feature we can intercept the method call. Its counterpart technique for Aspect Oriented Programming (AOP) in Spring. Its helps to analysis the business methods and these interceptors are disabled by default. so we can enable/disable the interceptor in deployment time through beans.xml  file. Create interceptor      To create interceptor involves two step process. first to create interceptor binding and  implement the interceptors. here we create Log Interceptor, so we need to create Log Interceptor Binding(its  like qualifier) Log.java here @InterceptorBinding is represent that the annotation 'Log' is interceptor second, we need to implement the interceptors LogImpl.java here @Interceptor represent that it...

This is Third  part of CDI discussion.Please visit   first part  and part two , @Alternative In part two  we seen @qualifier 's to resolve the unambiguous problem for one interface and more than on implementation. In qualifier helps to solve in development time. (i.e all meta information is stored in class files). Another solution is @Alternative annotation solve the problem in  deployment  time. all configuration is stored in beans.xml in WEB-INF folder We take same example what we discussed in last part  one interface (Hello) and two implementation(HelloImplOne, HelloImplTwo) here i marked @Alternative in both implementation Hello Interface HelloImplOne Implementation HelloImplTwo Implementation and go and modify the beans.xml in WEB_INF folder In <alternatives> tag in beans.xml we need specify which one need to inject. See the screen cast for demo...

This is second part of CDI discussion. If u r not visited, Please visit first part , Qualifier            Its annotation, its helps to create our qualifier annotation. We already seen if we have more than one implementation of particular interface then we can't inject, because ambiguity issues are arise. so we need to define own qualifiers and marked the annotation with that qualifier. When inject we need to mention the qualifier. For Example We have one interface and two implementation Hello Interface HelloImplOne Implementation HelloImplTwo Implementation  In Injection  Point (i.e where u inject the class, i.e where u use @inject key word) if u try to inject using interface like this u get AmbiguousResolutionException. but we can still use like this @javax.inject.Inject HelloImplOne hello; @javax.inject.Inject HelloImplTwo hello; so we need use qualifier we can create own qulaifier li...