added missing code which are mentioned in article

spring-boot-rest/src/main/java/com/baeldung/web/controller/FooController.java

@@ -4,6 +4,8 @@ import java.util.List;
 
 import javax.servlet.http.HttpServletResponse;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.data.domain.Page;
@@ -11,6 +13,7 @@ import org.springframework.data.domain.Pageable;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -25,6 +28,8 @@ import org.springframework.web.util.UriComponentsBuilder;
 
 import com.baeldung.persistence.model.Foo;
 import com.baeldung.persistence.service.IFooService;
+import com.baeldung.web.exception.CustomException1;
+import com.baeldung.web.exception.CustomException2;
 import com.baeldung.web.exception.MyResourceNotFoundException;
 import com.baeldung.web.hateoas.event.PaginatedResultsRetrievedEvent;
 import com.baeldung.web.hateoas.event.ResourceCreatedEvent;
@@ -36,6 +41,8 @@ import com.google.common.base.Preconditions;
 @RequestMapping(value = "/foos")
 public class FooController {
 
+    private static final Logger logger = LoggerFactory.getLogger(FooController.class);
+    
     @Autowired
     private ApplicationEventPublisher eventPublisher;
 
@@ -137,4 +144,10 @@ public class FooController {
     public void delete(@PathVariable("id") final Long id) {
         service.deleteById(id);
     }
+    
+    @ExceptionHandler({ CustomException1.class, CustomException2.class })
+    public void handleException(final Exception ex) {
+        final String error = "Application specific error handling";
+        logger.error(error, ex);
+    }
 }

spring-boot-rest/src/main/java/com/baeldung/web/error/RestResponseStatusExceptionResolver.java

@@ -0,0 +1,73 @@
+package com.baeldung.web.error;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Component;
+import org.springframework.web.servlet.ModelAndView;
+import org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.dataformat.xml.XmlMapper;
+
+@Component
+public class RestResponseStatusExceptionResolver extends AbstractHandlerExceptionResolver {
+
+    private static final Logger logger = LoggerFactory.getLogger(RestResponseStatusExceptionResolver.class);
+    
+    @Override
+    protected ModelAndView doResolveException(HttpServletRequest request, 
+        HttpServletResponse response, Object handler, Exception ex) {
+        try {
+            if (ex instanceof IllegalArgumentException) {
+                return handleIllegalArgument(
+                  (IllegalArgumentException) ex, request, response, handler);
+            }
+        } catch (Exception handlerException) {
+            logger.warn("Handling of [{}] resulted in Exception", ex.getClass().getName(), handlerException);
+        }
+        return null;
+    }
+
+    private ModelAndView handleIllegalArgument(IllegalArgumentException ex, 
+        final HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
+        final String accept = request.getHeader(HttpHeaders.ACCEPT);
+        
+        response.sendError(HttpServletResponse.SC_CONFLICT);
+        response.setHeader("ContentType", accept);
+        
+        final ModelAndView modelAndView = new ModelAndView("error");
+        modelAndView.addObject("error", prepareErrorResponse(accept));
+        return modelAndView;
+    }
+    
+    /** Prepares error object based on the provided accept type.
+     * @param accept The Accept header present in the request.
+     * @return The response to return
+     * @throws JsonProcessingException
+     */
+    private String prepareErrorResponse(String accept) throws JsonProcessingException {
+        final Map<String, String> error = new HashMap<>();
+        error.put("Error", "Application specific error message");
+        
+        final String response;
+        if(MediaType.APPLICATION_JSON_VALUE.equals(accept)) {
+            response = new ObjectMapper().writeValueAsString(error);
+        } else {
+            response = new XmlMapper().writeValueAsString(error);
+        }
+        
+        return response;
+    }
+    
+    
+
+}

spring-boot-rest/src/main/java/com/baeldung/web/exception/CustomException1.java

@@ -0,0 +1,7 @@
+package com.baeldung.web.exception;
+
+public class CustomException1 extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+}

spring-boot-rest/src/main/java/com/baeldung/web/exception/CustomException2.java

@@ -0,0 +1,7 @@
+package com.baeldung.web.exception;
+
+public class CustomException2 extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+}

spring-boot-rest/src/main/java/com/baeldung/web/exception/MyResourceNotFoundException.java

@@ -1,5 +1,9 @@
 package com.baeldung.web.exception;
 
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(value = HttpStatus.NOT_FOUND)
 public final class MyResourceNotFoundException extends RuntimeException {
 
     public MyResourceNotFoundException() {

spring-boot-rest/src/test/java/com/baeldung/web/FooControllerWebLayerIntegrationTest.java

@@ -10,8 +10,10 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import java.util.Collections;
 
 import org.hamcrest.Matchers;
+import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.Mockito;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
 import org.springframework.boot.test.mock.mockito.MockBean;
@@ -24,6 +26,7 @@ import org.springframework.test.web.servlet.MockMvc;
 import com.baeldung.persistence.model.Foo;
 import com.baeldung.persistence.service.IFooService;
 import com.baeldung.web.controller.FooController;
+import com.baeldung.web.exception.CustomException1;
 import com.baeldung.web.hateoas.event.PaginatedResultsRetrievedEvent;
 
 /**
@@ -56,5 +59,15 @@ public class FooControllerWebLayerIntegrationTest {
             .andExpect(status().isOk())
             .andExpect(jsonPath("$",Matchers.hasSize(1)));
     }
-
+    
+    @Test
+    public void delete_forException_fromService() throws Exception {
+        Mockito.when(service.findAll()).thenThrow(new CustomException1());
+        this.mockMvc.perform(get("/foos")).andDo(h ->  {
+            final Exception expectedException = h.getResolvedException();
+            Assert.assertTrue(expectedException instanceof CustomException1);
+            
+        });
+    }
+    
 }