There is the part of the UI Controller

@Controller
public class UiController {
										
    ...
										
    @RequestMapping("/")
    public String summary(HttpServletRequest request, HttpServletResponse response) {
        return "index";
    }
										
    @RequestMapping("/contacts")
        public String contacts(HttpServletRequest request, HttpServletResponse response) {
        return "contacts";
    }
										
    @RequestMapping("/about")
    public String about(HttpServletRequest request, HttpServletResp
        return "about";
    }
    ...
}

We need to check for every endpoint (methods): if a request comes from the ip which is contained in “blacklist” then error403.html (or what ever you want) should be returned.

@Controller
public class UiController {
										
    @Resource
    BlackList blackList;
    ...
										
    @RequestMapping("/")
    public String summary(HttpServletRequest request, HttpServletResponse response) {
        if (blackList.isIpInBlackList(request.getRemoteAddr()) {
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return "errors/error403";
        }
        return "index";
    }
										
    @RequestMapping("/contacts")
    public String contacts(HttpServletRequest request, HttpServletResponse response) {
        if (blackList.isIpInBlackList(request.getRemoteAddr()) {
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return "errors/error403";
        }
        return "contacts";
    }
										
    @RequestMapping("/about")
    public String about(HttpServletRequest request, HttpServletResponse response) {
        if (blackList.isIpInBlackList(request.getRemoteAddr()) {
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return "errors/error403";
        }
        return "about";
    }
										
    ...
}

AspectJ lets us to remove repeated “non business code” and place it to the “aspect”.

@Aspect
@Component
public class BlackListAspect {
										
    @Resource
    BlackList blackList;
										
    @Around("execution(* web.ui.UiController.*(..))")
    public String blackListFiltering(ProceedingJoinPoint jp) throws Throwable {
        Object[] args = jp.getArgs();
        HttpServletRequest request = (HttpServletRequest) args[0];
        HttpServletResponse response = (HttpServletResponse) args[1];
										
        if (blackList.isIpInBlackList(request.getRemoteAddr())) {
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return "errors/error403";
        }
        Object result = jp.proceed(args);
        return result.toString();
    }
}

Aspect weaving

The last thing we need to setup is pom.xml to properly weave our aspects.

There are some differences between Spring and non-Spring projects so carefully read this - Aspect weaving in Spring and non-Spring projects

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