BAEL-4564 Sample code for article filters vs spring handler interceptor

spring-boot-modules/spring-boot-mvc-3/README.md

@@ -9,4 +9,5 @@ This module contains articles about Spring Web MVC in Spring Boot projects.
 - [Spring MVC Async vs Spring WebFlux](https://www.baeldung.com/spring-mvc-async-vs-webflux)
 - [Differences in @Valid and @Validated Annotations in Spring](https://www.baeldung.com/spring-valid-vs-validated)
 - [CharacterEncodingFilter In SpringBoot](https://www.baeldung.com/spring-boot-characterencodingfilter)
+ [Difference Between Interceptors and Filters in Spring MVC](https://www.baeldung.com/difference-between-interceptors-and-filters-in-spring-mvc/)
 - More articles: [[prev -->]](/spring-boot-modules/spring-boot-mvc-2)

spring-boot-modules/spring-boot-mvc-3/src/main/java/com/baeldung/filtersinterceptors/FilterInterceptorApp.java

@@ -0,0 +1,12 @@
+package com.baeldung.filtersinterceptors;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.scheduling.annotation.EnableAsync;
+
+@SpringBootApplication(scanBasePackages = "com.baeldung.filtersinterceptors")
+public class FilterInterceptorApp {
+    public static void main(String[] args) {
+        SpringApplication.run(FilterInterceptorApp.class, args);
+    }
+}

spring-boot-modules/spring-boot-mvc-3/src/main/java/com/baeldung/filtersinterceptors/HelloConroller.java

@@ -0,0 +1,19 @@
+package com.baeldung.filtersinterceptors;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+
+@Controller
+public class HelloConroller {
+	
+	private Logger logger = LoggerFactory.getLogger(HelloConroller.class);
+	
+	@GetMapping("/hello")
+	public String hello() {
+		logger.info("Hello from the controller");
+		return "hello";
+	}
+	
+}

spring-boot-modules/spring-boot-mvc-3/src/main/java/com/baeldung/filtersinterceptors/LogFilter.java

@@ -0,0 +1,27 @@
+package com.baeldung.filtersinterceptors;
+
+import java.io.IOException;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+@Component
+public class LogFilter implements Filter {
+
+	private Logger logger = LoggerFactory.getLogger(LogFilter.class);
+	
+	@Override
+	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+			throws IOException, ServletException {
+		logger.info("Hello from: "+request.getLocalAddr());
+		chain.doFilter(request, response);
+	}
+
+}

spring-boot-modules/spring-boot-mvc-3/src/main/java/com/baeldung/filtersinterceptors/LogInterceptor.java

@@ -0,0 +1,36 @@
+package com.baeldung.filtersinterceptors;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+import org.springframework.web.servlet.HandlerInterceptor;
+import org.springframework.web.servlet.ModelAndView;
+
+@Component
+public class LogInterceptor implements HandlerInterceptor{
+
+	private Logger logger = LoggerFactory.getLogger(LogInterceptor.class);
+	
+	@Override
+	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
+			throws Exception {
+		logger.info("preHandle");
+		return true;
+	}
+	
+	@Override
+	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
+			ModelAndView modelAndView) throws Exception {
+		logger.info("postHandle");
+	}
+	
+	@Override
+	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
+			throws Exception {
+		logger.info("afterCompletion");
+	}
+	
+}

spring-boot-modules/spring-boot-mvc-3/src/main/java/com/baeldung/filtersinterceptors/WebMvcConfig.java

@@ -0,0 +1,21 @@
+package com.baeldung.filtersinterceptors;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+public class WebMvcConfig implements WebMvcConfigurer   {
+
+	private final LogInterceptor logInterceptor;
+	
+	public WebMvcConfig(LogInterceptor logInterceptor) {
+		this.logInterceptor = new LogInterceptor();
+	}
+	
+	@Override
+	public void addInterceptors(InterceptorRegistry registry) {
+		registry.addInterceptor(logInterceptor).addPathPatterns("/**");
+	}
+	
+}

spring-boot-modules/spring-boot-mvc-3/src/main/resources/templates/hello.html

@@ -0,0 +1,10 @@
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+<title>Spring Filters vs Interceptors</title>
+</head>
+
+<body>
+	<h3>Hello</h3>
+</body>
+</html>