@ControllerAdvice is a specialization of @Component which can be used to define methods with @ExceptionHandler, @InitBinder, and @ModelAttribute annotations. Such methods are applied to all @RequestMapping methods across multiple @Controller classes instead of just local @Controller class.
Following example shows how to use @ModelAttribute in @ControllerAdvice class to globally apply module attributes.
Example
We are going to populate module attributes with the page counter and the request URI in the @ControllerAdvice class.
package com.logicbig.example;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ModelAttribute;
import javax.servlet.http.HttpServletRequest;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.LongAdder;
@ControllerAdvice
public class PageCountersControllerAdvice {
//uri to counter map
private ConcurrentHashMap<String, LongAdder> counterMap = new ConcurrentHashMap<>();
@ModelAttribute
public void handleRequest(HttpServletRequest request, Model model) {
String requestURI = request.getRequestURI();
//counter increment for each access to a particular uri
counterMap.computeIfAbsent(requestURI, key -> new LongAdder())
.increment();
//populating counter in the model
model.addAttribute("counter", counterMap.get(requestURI).sum());
//populating request URI in the model
model.addAttribute("uri", requestURI);
}
}
The Controllers
@Controller
public class ProductsController {
@RequestMapping("/products/**")
public String handleRequest(){
//todo:prepare page content
return "app-page";
}
}
@Controller
public class ServicesController {
@RequestMapping("/services/**")
public String handleRequest() {
//todo:prepare page content
return "app-page";
}
}
The view
src/main/webapp/WEB-INF/views/app-page.jsp<html>
<body>
<p>Page counter: ${counter}</p>
<p>App content .... at ${uri}</p>
</body>
</html>
Output
To try examples, run embedded tomcat (configured in pom.xml of example project below):
mvn tomcat7:run-war Accessing and refreshing pages multiple times:
As seen above, page counter is maintained and supplied as module attribute for both of our controllers.
Example ProjectDependencies and Technologies Used: - spring-webmvc 5.0.5.RELEASE: Spring Web MVC.
- javax.servlet-api 3.0.1 Java Servlet API
- JDK 1.8
- Maven 3.3.9
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