Merge pull request #5019 from kartiksingla/BAEL-1302

[BAEL-1302] - Overview and Need of DelegatingFilterProxy in spring

spring-5-mvc/src/main/java/com/baeldung/Spring5Application.java

@@ -1,7 +1,11 @@
 package com.baeldung;
 
+import javax.servlet.Filter;
+
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.web.filter.DelegatingFilterProxy;
+import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
 
 @SpringBootApplication
 public class Spring5Application {
@@ -10,4 +14,31 @@ public class Spring5Application {
         SpringApplication.run(Spring5Application.class, args);
     }
 
+    public static class ApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
+
+        @Override
+        protected Class<?>[] getRootConfigClasses() {
+            return null;
+        }
+
+        @Override
+        protected Class<?>[] getServletConfigClasses() {
+            // TODO Auto-generated method stub
+            return null;
+        }
+
+        @Override
+        protected String[] getServletMappings() {
+            // TODO Auto-generated method stub
+            return null;
+        }
+
+        @Override
+        protected javax.servlet.Filter[] getServletFilters() {
+            DelegatingFilterProxy delegateFilterProxy = new DelegatingFilterProxy();
+            delegateFilterProxy.setTargetBeanName("loggingFilter");
+            return new Filter[] { delegateFilterProxy };
+        }
+    }
+
 }

spring-5-mvc/src/main/java/com/baeldung/spring/filter/CustomFilter.java

@@ -0,0 +1,38 @@
+package com.baeldung.spring.filter;
+
+import java.io.IOException;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+@Component("loggingFilter")
+public class CustomFilter implements Filter {
+    
+    private static Logger LOGGER = LoggerFactory.getLogger(CustomFilter.class);
+
+    @Override
+    public void init(FilterConfig config) throws ServletException {
+    }
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response, 
+            FilterChain chain) throws IOException, ServletException {
+        HttpServletRequest req = (HttpServletRequest) request;
+        LOGGER.info("Request Info : " + req);
+        chain.doFilter(request, response);
+    }
+
+    @Override
+    public void destroy() {
+        // cleanup code, if necessary
+    }
+}

spring-5-mvc/src/main/webapp/WEB-INF/web.xml

@@ -16,6 +16,14 @@
         <servlet-name>functional</servlet-name>
         <url-pattern>/</url-pattern>
     </servlet-mapping>
+	<filter>
+		<filter-name>loggingFilter</filter-name>
+		<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
+	</filter>
 
+	<filter-mapping>
+		<filter-name>loggingFilter</filter-name>
+		<url-pattern>/*</url-pattern>
+	</filter-mapping>
 
 </web-app>