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Spring : ResponseEntity<String> return empty value

I'm working with a small module with Spring (5.0.8) and i'm looking to make some logs for debugging purposes.
My ResponseEntity return an empty value and after some research, I can't figure out why.
I've been going through some post like this one Spring: Returning empty HTTP Responses with ResponseEntity<Void> doesn't work but i haven't found a suitable solution for my case.
private RestTemplate buildRestTemplate() {
RestTemplate restTemplate = buildBasicRestTemplate();
restTemplate.getInterceptors().add(new BasicAuthorizationInterceptor(
REST_ADMIN_USERNAME,
REST_ADMIN_PASSWORD));
return restTemplate;
}
RestTemplate restTemplate = buildRestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<ActivityLogBean> entity = new HttpEntity<ActivityLogBean>(headers);
String resourceUrl = "http://localhost:8080/rest/data/timestamp"
ResponseEntity<String> response = restTemplate.exchange(uriWithParams, HttpMethod.GET, entity, String.class);

How to Mock REST API in unit testing?

I am using RestTemplate exchange HttpMethod.POST method to POST to an endpoint. In my test file I am testing for success of the POST method. However with my current tests I am getting 401 Unauthorized error when POST request is made. I need help to Mock the API while making POST request in test file
Here is my main file
#Component
public class DataTestRepo {
private final RestTemplate restTemplate;
private final String url;
private final AllBuilder headersBuilder;
public DataTestRepo(
#Qualifier(Oauth.BEAN_NAME) AllBuilder headersBuilder,
RestTemplate restTemplate, String url) {
this.headersBuilder = headersBuilder;
this.restTemplate = restTemplate;
this.url = url;
}
public ResponseEntity<String> postJson(Set<String> results) {
ResponseEntity<String> result = null;
try {
JSONObject jsonObject = new JSONObject(body);
HttpEntity<String> request = new HttpEntity<String>(jsonObject.toString(), null);
restTemplate.getMessageConverters().add(stringConvertor);
result = restTemplate.exchange(url, HttpMethod.POST,
new HttpEntity<>(request, getHttpHeaders()), String.class);
}
return result;
}
}
Here is my test file
#RunWith(MockitoJUnitRunner.class)
#TestPropertySource
public class DataTestRepoTest {
private static final String url = "http://localhost:8080/data/name";
#Mock
private DataTestRepo DataTestRepo;
RestTemplate restTemplate = new RestTemplate();
#Test
public void restTemplateHttpPost_success() throws URISyntaxException {
URI uri = new URI(url);
Set<String> mockData = Stream.of("A","B").collect(Collectors.toSet());
Map<String, String> body = new HashMap<>();
body.put("Name", "Aws");
JSONObject jsonObject = new JSONObject(body);
HttpEntity<String> request = new HttpEntity<>(jsonObject.toString(), null);
ResponseEntity<String> result = restTemplate.exchange(uri, HttpMethod.POST,
new HttpEntity<>(request, DataTestRepo.getHttpHeaders()), String.class);
Assert.assertEquals(201, result.getStatusCodeValue());
}
}

You are testing the logic inside DataTestRepo class, so you should not mock it.
RestTemplate is a dependency inside DataTestRepo, so this is exactly what you need to mock.
In general it should look like this inside your test:
#InjectMocks
private DataTestRepo DataTestRepo;
#Mock
RestTemplate restTemplate;
Also, you will have to provide a return value for your mocked dependency, like this:
Mockito.when(restTemplate.exchange(ArgumentMatchers.any(), ArgumentMatchers.any(), ArgumentMatchers.any(), ArgumentMatchers.any())).thenReturn(new ResponseEntity<>(yourExpectedDataHere, HttpStatus.OK));
enter code here
This is just a simple example. A good practice would be to check that the arguments passed to your mock equal to the expected ones. One way would be to replace ArgumentMatchers.any() with the real expected data. Another is to verify it separately, like this:
Mockito.verify(restTemplate, Mockito.times(1)).exchange(ArgumentsMatchers.eq(yourExpectedDataHere), ArgumentsMatchers.eq(yourExpectedDataHere), ArgumentsMatchers.eq(yourExpectedDataHere), ArgumentsMatchers.eq(yourExpectedDataHere));

This is a great read on this topic: https://reflectoring.io/spring-boot-web-controller-test/

Multipart files http request with Spring Rest Template arrives without the files

I have this client for sending multipart file http requests with Rest Template
#Component
public class RestTemplatePost {
#Bean
public RestTemplate restTemplate() {
return new RestTemplate();
}
#PostConstruct
public void prepareMessage() throws Exception {
File file = new File("****");
File file2 = new File("****");
HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);
MultiValueMap<String, Object> form = new LinkedMultiValueMap<>();
form.add("files", file);
form.add("files", file2);
form.add("usertoken", "test");
form.add("sendTo", "test);
form.add("subject", "test");
form.add("content", "test");
HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(form, httpHeaders);
String serverUrl = "http://localhost:8080/api/mails/send";
List<HttpMessageConverter<?>> httpMessageConverters = new ArrayList<>();
httpMessageConverters.add(new FormHttpMessageConverter());
httpMessageConverters.add(new MappingJackson2HttpMessageConverter());
restTemplate().setMessageConverters(httpMessageConverters);
restTemplate().postForEntity(serverUrl, requestEntity, String.class);
}
}
Then I have this server side that should receive the request:
#RestController
#RequestMapping("/api")
public class MainConroller {
private static final Logger log = LoggerFactory.getLogger(MainConroller.class);
#Autowired
private MainService mainService;
public MainConroller(MainService mainService) {
this.mainService = mainService;
}
#PostMapping("/mails/send")
public void send(
#RequestParam("usertoken") String usertoken,
#RequestParam("sendTo") String sendTo,
#RequestParam("subject") String subject,
#RequestParam("content") String content,
#RequestParam(required = false, name = "files") List<MultipartFile> multipartFiles) {
log.debug("{}, {}, {}, {}", usertoken, sendTo, subject, content);
mainService.processMessage(usertoken, sendTo, subject, content, multipartFiles);
}
}
When I send this request from the client side, everything arrives on the server side except the files.
The RequestParam files is empty after receiving the request.
Update
Message converters explicitly removed as recommended, nothing changed.

No files are sent because there is no HttpMessageConverter capable of converting a java.io.File.
On the other hand, there is a ResourceHttpMessageConverter which converts all kinds of Resource, including FileSystemResource.
PS FormHttpMessageConverter is added by default when RestTemplate is created and FormHttpMessageConverter also uses it under the hood.

How to send JSON as a Input parameter from one Microservice to another using RestTemplate in Spring Boot

I want to send JSON as an input from Microservice M1 to a Microservice M2.
M1 and M2 both are on different machines.
I am new to Spring Boot,
I found some code but I am unable to get it.
Please help.

make a class on both microservices or make a jar of that class and add to both microservices so that they both can access the same data.
Lets say the class is
class TestData{
private String name;
private String id;
// getters and setters
}
Now you can send data from M1 to M2 as following
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
TestData data = new TestData();
HttpEntity<?> entity = new HttpEntity<Object>(data,headers);
ResponseEntity<Object> responseEntity = restTemplate.exchange("url", HttpMethod.POST, entity, Object.class);
In Microservice M2 you can write a controller to get the data and process it as follows
#RequestMapping(value="/url",method=RequestMethod.POST)
public Object do(#RequestBody TestData data){
// do something
return //something
}

Let's Say Your Have MicroService1 which needs to send JSONObject => JsonObject to another MicroService2 which is on different Machine but on same network .
Sender Side:
RestTemplate restTemplate = new RestTemplate();
String jsonString = restTemplate.postForObject("http://10.177.7.128:8080/user/insertJsonObject",jsonObject,String.class);
Syntax for restTemplate.postForObject is:
ResponseType var1 = restTemplate.postForObject("network ip Address:portnumber/path",JSONObject,ResponseType)
To Know the URI go to System Preferences > Network
To Receive the object at the receiver Side
#RequestMapping(value="/user/insertJsonObject", method=RequestMethod.POST)
public String updateProductSold(#RequestBody JSONObject jsonObject) {
...Body
...
...
return responseStatus;

Here is the sample code
public class Test {
public static void main(String[] args) {
String jsonString = "{\"id\" : \"123\",\"name\" : \"Tom\",\"class\" : {\"subject\" : \"Math\",\"teacher\" : \"Jack\"}}";
RestTemplate restTemplate = new RestTemplate();
String url = "http://192.1168.1.190:8080/test" // url for second service
System.out.println(responserEntityValue(jsonString,restTemplate,url,HttpMethod.POST,String.class));
}
public ResponseEntity<String> responserEntityValue(final String body, final RestTemplate restTemplate,
final String uRL, final HttpMethod requestMethod, final Class<String> stringClass) {
HttpHeaders headers = new HttpHeaders();
// Set all headers
headers.add(DatabaseConstants.CONTENT_TYPE, "application/json");
HttpEntity<String> request = new HttpEntity<>(body, headers);
return restTemplate.exchange(uRL, requestMethod, request, stringClass);
}

How to extract HTTP status code from the RestTemplate call to a URL?

I am using RestTemplate to make an HTTP call to our service which returns a simple JSON response. I don't need to parse that JSON at all. I just need to return whatever I am getting back from that service.
So I am mapping that to String.class and returning the actual JSON response as a string.
RestTemplate restTemplate = new RestTemplate();
String response = restTemplate.getForObject(url, String.class);
return response;
Now the question is -
I am trying to extract HTTP Status codes after hitting the URL. How can I extract HTTP Status code from the above code? Do I need to make any change into that in the way I doing it currently?
Update:-
This is what I have tried and I am able to get the response back and status code as well. But do I always need to set HttpHeaders and Entity object like below I am doing it?
RestTemplate restTemplate = new RestTemplate();
//and do I need this JSON media type for my use case?
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
//set my entity
HttpEntity<Object> entity = new HttpEntity<Object>(headers);
ResponseEntity<String> out = restTemplate.exchange(url, HttpMethod.GET, entity, String.class);
System.out.println(out.getBody());
System.out.println(out.getStatusCode());
Couple of question - Do I need to have MediaType.APPLICATION_JSON as I am just making a call to url which returns a response back, it can return either JSON or XML or simple string.

Use the RestTemplate#exchange(..) methods that return a ResponseEntity. This gives you access to the status line and headers (and the body obviously).
getStatusCode()
getHeaders()

If you don´t want to leave the nice abstraction around RestTemplate.get/postForObject... methods behind like me and dislike to fiddle around with the boilerplate stuff needed when using RestTemplate.exchange... (Request- and ResponseEntity, HttpHeaders, etc), there´s another option to gain access to the HttpStatus codes.
Just surround the usual RestTemplate.get/postForObject... with a try/catch for org.springframework.web.client.HttpClientErrorException and org.springframework.web.client.HttpServerErrorException, like in this example:
try {
return restTemplate.postForObject("http://your.url.here", "YourRequestObjectForPostBodyHere", YourResponse.class);
} catch (HttpClientErrorException | HttpServerErrorException httpClientOrServerExc) {
if(HttpStatus.NOT_FOUND.equals(httpClientOrServerExc.getStatusCode())) {
// your handling of "NOT FOUND" here
// e.g. throw new RuntimeException("Your Error Message here", httpClientOrServerExc);
}
else {
// your handling of other errors here
}
The org.springframework.web.client.HttpServerErrorException is added here for the errors with a 50x.
Now you´re able to simple react to all the StatusCodes you want - except the appropriate one, that matches your HTTP method - like GET and 200, which won´t be handled as exception, as it is the matching one. But this should be straight forward, if you´re implementing/consuming RESTful services :)

If you want all the HTTPStatus from a RestTemplate including 4XX and 5XX, you will have to provide an ResponseErrorHandler to the restTemplate, since the default handler will throw an exception in case of 4XX or 5XX
We could do something like that :
RestTemplate restTemplate = new RestTemplate();
restTemplate.setErrorHandler(new DefaultResponseErrorHandler() {
#Override
public boolean hasError(HttpStatus statusCode) {
return false;
}
});
ResponseEntity<YourResponse> responseEntity =
restTemplate.getForEntity("http://your.url.here", YourResponse.class);
assertThat(responseEntity.getStatusCode()).isEqualTo(HttpStatus.XXXX);

private RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> response = restTemplate.exchange(url,HttpMethod.GET, requestEntity,String.class);
response contains 'body', 'headers' and 'statusCode'
to get statusCode : response.getStatusCode();

exchange(...) works but if you want less code, you can use
org.springframework.boot.test.web.client.TestRestTemplate.getForEntity(...)
which returns an Entity containing StatusCode. Change your example code to this:
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
HttpStatus statusCode = response.getStatusCode();
To test it you can use this snippet from my unit test:
ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
assertResponseHeaderIsCorrect(response, HttpStatus.OK);
/**
* Test the basics of the response, non-null, status expected, etc...
*/
private void assertResponseHeaderIsCorrect(ResponseEntity<String> response, HttpStatus expectedStatus) {
assertThat(response).isNotNull();
assertThat(response.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_JSON_UTF8);
assertThat(response.getStatusCode()).isEqualTo(expectedStatus);
}

There can be some slightly trickier use cases someone might fall in (as I did). Consider the following:
Supporting a Page object in order to use it with RestTemplate and ParameterizedTypeReference:
RestPageResponse:
import java.util.ArrayList;
import java.util.List;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.Pageable;
public class RestResponsePage<T> extends PageImpl<T>{
private static final long serialVersionUID = 3248189030448292002L;
public RestResponsePage(List<T> content, Pageable pageable, long total) {
super(content, pageable, total);
}
public RestResponsePage(List<T> content) {
super(content);
}
public RestResponsePage() {
super(new ArrayList<T>());
}
}
Using ParameterizedTypeReference will yield the following:
ParameterizedTypeReference<RestResponsePage<MyObject>> responseType =
new ParameterizedTypeReference<RestResponsePage<MyObject>>() {};
HttpEntity<RestResponsePage<MyObject>> response = restTemplate.exchange(oauthUrl, HttpMethod.GET, entity, responseType);
Calling #exchange:
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);
HttpEntity<?> entity = new HttpEntity<>(headers);
response = restTemplate.exchange("localhost:8080/example", HttpMethod.GET, entity, responseType);
Now here is the "tricky" part.
Trying to call exchange's getStatusCode will be impossible because the compiler, unfortunately, will be unaware of the "intended" type of response.
That is because generics are implemented via type erasure which removes all information regarding generic types during compilation (read more - source)
((ResponseEntity<RestResponsePage<MyObject>>) response).getStatusCode()
In this case, you have to explicitly cast the variable to the desired Class to get the statusCode (and/or other attributes)!

Putting this much of code is enough for me
HttpStatus statusCode = ((ResponseEntity<Object>) responseOfEsoft).getStatusCode();

You can use this solution
RestTemplate restTemplate = new RestTemplate();
final String baseUrl = "http://www.myexampleurl.com";
URI uri = new URI(baseUrl);
ResponseEntity<String> result = restTemplate.getForEntity(uri, String.class);
//get status code
int statuCode = result.getStatusCodeValue();

Was able to solve this through:
HttpEntity<Object> entity = restTemplate.getForEntity(uri, Object.class);
ResponseEntity<String> result = restTemplate.exchange(uri, HttpMethod.GET, entity, String.class);
System.out.println(result.getStatusCode());