Basic authentication for REST API using spring restTemplate

I am completely new in RestTemplate and basically in the REST APIs also. I want to retrieve some data in my application via Jira REST API, but getting back 401 Unauthorised. Found and article on jira rest api documentation but don't really know how to rewrite this into java as the example uses the command line way with curl. I would appreciate any suggestion or advice how to rewrite:

curl -D- -X GET -H "Authorization: Basic ZnJlZDpmcmVk" -H "Content-Type: application/json" "http://kelpie9:8081/rest/api/2/issue/QA-31"

into java using spring rest template. Where the ZnJlZDpmcmVk is a base64 encoded string of username:password. Thank you very much.

Taken from the example on this site, I think this would be the most natural way of doing it, by filling in the header value and passing the header to the template.

This is to fill in the header Authorization:

String plainCreds = "willie:p@ssword";
byte[] plainCredsBytes = plainCreds.getBytes();
byte[] base64CredsBytes = Base64.encodeBase64(plainCredsBytes);
String base64Creds = new String(base64CredsBytes);

HttpHeaders headers = new HttpHeaders();
headers.add("Authorization", "Basic " + base64Creds);

And this is to pass the header to the REST template:

HttpEntity<String> request = new HttpEntity<String>(headers);
ResponseEntity<Account> response = restTemplate.exchange(url, HttpMethod.GET, request, Account.class);
Account account = response.getBody();

You may use spring-boot RestTemplateBuilder

@Bean
RestOperations rest(RestTemplateBuilder restTemplateBuilder) {
    return restTemplateBuilder.basicAuthentication("user", "password").build();
}

See documentation

(before SB 2.1.0 it was #basicAuthorization)

There are multiple ways to add the basic HTTP authentication to the RestTemplate.

1. For a single request

try {
    // request url
    String url = "https://jsonplaceholder.typicode.com/posts";

    // create auth credentials
    String authStr = "username:password";
    String base64Creds = Base64.getEncoder().encodeToString(authStr.getBytes());

    // create headers
    HttpHeaders headers = new HttpHeaders();
    headers.add("Authorization", "Basic " + base64Creds);

    // create request
    HttpEntity request = new HttpEntity(headers);

    // make a request
    ResponseEntity<String> response = new RestTemplate().exchange(url, HttpMethod.GET, request, String.class);

    // get JSON response
    String json = response.getBody();

} catch (Exception ex) {
    ex.printStackTrace();
}

If you are using Spring 5.1 or higher, it is no longer required to manually set the authorization header. Use headers.setBasicAuth() method instead:

// create headers
HttpHeaders headers = new HttpHeaders();
headers.setBasicAuth("username", "password");

2. For a group of requests

@Service
public class RestService {

    private final RestTemplate restTemplate;

    public RestService(RestTemplateBuilder restTemplateBuilder) {
        this.restTemplate = restTemplateBuilder
                .basicAuthentication("username", "password")
                .build();
    }

   // use `restTemplate` instance here
}

3. For each and every request

@Bean
RestOperations restTemplateBuilder(RestTemplateBuilder restTemplateBuilder) {
    return restTemplateBuilder.basicAuthentication("username", "password").build();
}

I hope it helps!

As of Spring 5.1 you can use HttpHeaders.setBasicAuth

Create Basic Authorization header:

String username = "willie";
String password = ":p@ssword";
HttpHeaders headers = new HttpHeaders();
headers.setBasicAuth(username, password);
...other headers goes here...

Pass the headers to the RestTemplate:

HttpEntity<String> request = new HttpEntity<String>(headers);
ResponseEntity<Account> response = restTemplate.exchange(url, HttpMethod.GET, request, Account.class);
Account account = response.getBody();

Documentation: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/http/HttpHeaders.html#setBasicAuth-java.lang.String-java.lang.String-

(maybe) the easiest way without importing spring-boot.

restTemplate.getInterceptors().add(new BasicAuthorizationInterceptor("user", "password"));

Reference Spring Boot's TestRestTemplate implementation as follows:

https://github.com/spring-projects/spring-boot/blob/v1.2.2.RELEASE/spring-boot/src/main/java/org/springframework/boot/test/TestRestTemplate.java

Especially, see the addAuthentication() method as follows:

private void addAuthentication(String username, String password) {
	if (username == null) {
		return;
	}
	List<ClientHttpRequestInterceptor> interceptors = Collections
			.<ClientHttpRequestInterceptor> singletonList(new BasicAuthorizationInterceptor(
					username, password));
	setRequestFactory(new InterceptingClientHttpRequestFactory(getRequestFactory(),
			interceptors));
}

Similarly, you can make your own RestTemplate easily

by inheritance like TestRestTemplate as follows:

https://github.com/izeye/samples-spring-boot-branches/blob/rest-and-actuator-with-security/src/main/java/samples/springboot/util/BasicAuthRestTemplate.java

Instead of instantiating as follows:

TestRestTemplate restTemplate = new TestRestTemplate();

Just do it like this:

TestRestTemplate restTemplate = new TestRestTemplate(user, password);

It works for me, I hope it helps!

Use setBasicAuth to define credentials

HttpHeaders headers = new HttpHeaders();
headers.setBasicAuth("myUsername", myPassword);

Then create the request like you prefer.

Example:

HttpEntity<String> request = new HttpEntity<String>(headers);
ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.GET, 
request, String.class);
String body = response.getBody();

HttpHeaders headers = new HttpHeaders();
        headers.setBasicAuth(username, password);

then continue with the same procedure mentioned by the others here:

HttpEntity<String> request = new HttpEntity<String>(headers);
ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.GET, 
request, String.class);

I'm using spring version 5.3.15 for my unit test environment. I used withBasicAuth for my tests :

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class MyTestClass {
    ...
    @Autowired
    private TestRestTemplate restTemplate;
    ...
    @Test
    @SneakyThrows
    public void TestGetSettings(){
        DtoClass dtoClass  = this.restTemplate
                           .withBasicAuth(UserServices.DEFAULT_USER, UserServices.DEFAULT_PASSWORD)
                           .getForObject(String.format("http://localhost:%d/setting",
                port), DtoClass.class);
        assertThat(dtoClass.getClientAddress()).isNotEmpty();
    }
   ...
}

As you see this method only work for basic authentication. If you look at the details of the withBasicAuth method, you will find that the method source will be like this:

// TestRestTemplate.java file: 
...
public class TestRestTemplate {
    ... 
    private final RestTemplateBuilder builder;
    ...
    public TestRestTemplate withBasicAuth(String username, String password) {
      TestRestTemplate template = new TestRestTemplate(this.builder, username, password, this.httpClientOptions);
      ...
    }
}

As a result, for other types of authentication you can use the RestTemplateBuilder as a builder which is mentioned in other answers.