RestTemplate PATCH request

For cases where RestTemplate is built from a RestTemplateBuilder, constructor for the custom RestClient can be written as,

public PersonRestClient(RestTemplateBuilder restTemplateBuilder) {
  this.restTemplate = restTemplateBuilder.requestFactory(new HttpComponentsClientHttpRequestFactory()).build();
}

Also, the org.apache.httpcomponents.httpclient dependency needs to added to pom.

I solved this problem just adding a new HttpRequestFactory to my restTemplate instance. Like this

RestTemplate restTemplate = new RestTemplate();

HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
requestFactory.setConnectTimeout(TIMEOUT);
requestFactory.setReadTimeout(TIMEOUT);

restTemplate.setRequestFactory(requestFactory);

For TestRestTemplate, add

@Autowired
private TestRestTemplate restTemplate;

@Before
public void setup() {
    restTemplate.getRestTemplate().setRequestFactory(new HttpComponentsClientHttpRequestFactory());
}

PS: You will need add httpClient component in your project

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.4.1</version>
</dependency>

For me solved by adding below line:

restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());

I have added the below code in the java file. It worked for me.

String url="Your API URL";
RestTemplate restTemplate = new RestTemplate();
HttpClient httpClient = HttpClientBuilder.create().build();
restTemplate.setRequestFactory(new 
HttpComponentsClientHttpRequestFactory(httpClient));    
HttpHeaders reqHeaders = new HttpHeaders();
reqHeaders.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> requestEntity = new HttpEntity<String>(requestJson, reqHeaders);
ResponseEntity<String> responseEntity=restTemplate.exchange(url, HttpMethod.PATCH, 
requestEntity, String.class);

Also, need to add the below dependency in the pom.xml file.

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
</dependency>