Bytecode

One of the things that Spring 2.5 introduced back in 2007 was component scanning, a feature which removed the need for XML bean configuration and instead allowed developers to declare their beans using Java annotations. Rather than this: We can do this: It’s a pretty simple idea since Java makes it very easy to introspectively check a class’s annotations at runtime through its reflection API. Spring’s component scan feature also allows you to specify the base package(s) to scan for beans. ...

Earlier, I discussed the use of dynamic proxies and how they can be implemented in Java. As we saw, a necessary part of proxying classes is bytecode generation. From its onset, something I wanted to include in Infinitum was lazy loading. I also wanted to provide support for AOP down the road. Consequently, it was essential to include some way to generate bytecode at runtime. ...

I wanted to write about lazy loading, but doing so requires some background on proxies. Proxies are such an interesting and useful concept that I decided it would be worthwhile to write a separate post discussing them. I’ve talked about them in the past, for instance on StackOverflow, so this will be a bit of a rehash, but I will go into a little more depth here. What is a proxy? Fundamentally, it’s a broker, or mediator, between an object and that object’s user, which I will refer to as its client. Specifically, a proxy intercepts calls to the object, performs some logic, and then (typically) passes the call on to the object itself. I say typically because the proxy could simply intercept without ever calling the object. ...