1. Create project from “Spring initialz” with 3 dependencies:

a. Web

b. Actuator (Optional)

2. A REST Controller.

@RestController
public class EmployeeController {
    
    @RequestMapping(path = "/employee")
    public @ResponseBody Map<String, String> getEmployee(@RequestBody JsonNode jsonNode){
        String name = jsonNode.get("name").asText();
        System.err.println("[Calling][getEmployee][name]"+name);
        Map<String, String> namefEmployee = new HashMap<>();
        namefEmployee.put("Name of Employee", name);
        return namefEmployee;
    }
}

3. Run mvn spring-boot:run to start the service.

4. Testing with Postman client.

1. Create project from “Spring initialz” with 3 dependencies:

a. Web

b. Actuator (Optional)

2. Additional maven dependencies.

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
</dependency>

see full pom.xml
3. RestTemplate sample usage

import java.net.URISyntaxException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.client.RestTemplate;

public class SpringRestClient {

    private final RestTemplate restTemplate;

    public SpringRestClient() {
        ClientHttpRequestFactory requestFactory = getClientHttpRequestFactory();
        this.restTemplate = new RestTemplate(requestFactory);
        restTemplate.getMessageConverters().add(new StringHttpMessageConverter());
    }

    public void sendRequest2() throws URISyntaxException {
        String requestJsonString = "{ \"name\": \"user1\"}";

        String requestUrl = "http://localhost:8080/employee";

        // set headers
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);
        HttpEntity<String> entity = new HttpEntity<String>(requestJsonString, headers);

        // send request and parse result
        ResponseEntity<String> restResponse = restTemplate
                .exchange(requestUrl, HttpMethod.POST, entity, String.class);

        System.err.println("response string: " + restResponse.getBody());
    }

    private ClientHttpRequestFactory getClientHttpRequestFactory() {
        int timeout = 60000;
        RequestConfig config = RequestConfig.custom()
                .setConnectTimeout(timeout)
                .setConnectionRequestTimeout(timeout)
                .setSocketTimeout(timeout)
                .build();
        CloseableHttpClient client = HttpClientBuilder
                .create()
                .setDefaultRequestConfig(config)
                .build();
        return new HttpComponentsClientHttpRequestFactory(client);
    }
}

3. Run mvn spring-boot:run to test the project.

Confession:

1. I don’t know how spring security really works. I’m just sharing a attempt which worked for me. If you find any better approach to achieve this, please do share. I would love to know.

References:

1. Spring Security:
   1. boot-features-security
2. Authentication Provider:
   1. www.baeldung.com/spring-security-authentication-provider
   2. dzone.com/articles/spring-security-custom