BAEL-9319: Parsing the Response Body When the HTTP Request Has Return… (#18628)

* BAEL-9319: Parsing the Response Body When the HTTP Request Has Return Status 401 in Java

* BAEL-9319: Parsing the Response Body When the HTTP Request Has Return Status 401 in Java

* BAEL-9319: Parsing the Response Body When the HTTP Request Has Return Status 401 in Java

Author: achraftt

spring-web-modules/spring-resttemplate/src/main/java/com/baeldung/resttemplate/web/exception/UnauthorizedException.java

@@ -0,0 +1,7 @@
+package com.baeldung.resttemplate.web.exception;
+
+public class UnauthorizedException extends RuntimeException {
+    public UnauthorizedException(String message) {
+        super(message);
+    }
+}

spring-web-modules/spring-resttemplate/src/main/java/com/baeldung/resttemplate/web/service/BarConsumerService.java

@@ -1,10 +1,13 @@
 package com.baeldung.resttemplate.web.service;
 
+import com.baeldung.resttemplate.web.exception.UnauthorizedException;
 import com.baeldung.resttemplate.web.handler.RestTemplateResponseErrorHandler;
 import com.baeldung.resttemplate.web.model.Bar;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Service;
+import org.springframework.web.client.HttpStatusCodeException;
 import org.springframework.web.client.RestTemplate;
 
 @Service
@@ -15,12 +18,20 @@ public class BarConsumerService {
     @Autowired
     public BarConsumerService(RestTemplateBuilder restTemplateBuilder) {
         restTemplate = restTemplateBuilder
-          .errorHandler(new RestTemplateResponseErrorHandler())
-          .build();
+                .errorHandler(new RestTemplateResponseErrorHandler())
+                .build();
     }
 
     public Bar fetchBarById(String barId) {
-        return restTemplate.getForObject("/bars/4242", Bar.class);
+        try {
+            return restTemplate.getForObject("/bars/" + barId, Bar.class);
+        } catch (HttpStatusCodeException e) {
+            if (HttpStatus.UNAUTHORIZED == e.getStatusCode()) {
+                String responseBody = e.getResponseBodyAsString();
+                throw new UnauthorizedException("Unauthorized access: " + responseBody);
+            }
+            throw e;
+        }
     }
 
 }

spring-web-modules/spring-resttemplate/src/test/java/com/baeldung/resttemplate/web/service/BarConsumerServiceUnitTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.resttemplate.web.service;
+
+import com.baeldung.resttemplate.web.exception.UnauthorizedException;
+import com.baeldung.resttemplate.web.model.Bar;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.client.HttpClientErrorException;
+import org.springframework.web.client.RestTemplate;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+public class BarConsumerServiceUnitTest {
+
+    @Mock
+    private RestTemplateBuilder restTemplateBuilder;
+
+    @Mock
+    private RestTemplate restTemplate;
+
+    private BarConsumerService barConsumerService;
+
+    @BeforeEach
+    public void setup() {
+        when(restTemplateBuilder.errorHandler(any())).thenReturn(restTemplateBuilder);
+        when(restTemplateBuilder.build()).thenReturn(restTemplate);
+
+        barConsumerService = new BarConsumerService(restTemplateBuilder);
+    }
+
+    @Test
+    public void givenValidId_whenFetchingBar_thenReturnsBar() {
+        Bar expectedBar = new Bar();
+        expectedBar.setId("123");
+        expectedBar.setName("Test Bar");
+
+        when(restTemplate.getForObject(any(String.class), eq(Bar.class))).thenReturn(expectedBar);
+
+        Bar result = barConsumerService.fetchBarById("123");
+        assertEquals(expectedBar, result);
+    }
+
+    @Test
+    public void givenUnauthorizedResponse_whenFetchingBar_thenThrowsUnauthorizedException() {
+        String errorBody = "{\"error\": \"Invalid token\"}";
+        HttpClientErrorException exception = HttpClientErrorException.create(
+                HttpStatus.UNAUTHORIZED,
+                "Unauthorized",
+                null,
+                errorBody.getBytes(),
+                null
+        );
+
+        when(restTemplate.getForObject(any(String.class), eq(Bar.class))).thenThrow(exception);
+
+        UnauthorizedException thrown = assertThrows(
+                UnauthorizedException.class,
+                () -> barConsumerService.fetchBarById("123")
+        );
+
+        assertTrue(thrown.getMessage().contains(errorBody));
+    }
+}