post.java

 public void httpPostRequestWithHeadersAndBody() 
 {
        String url = "http://localhost:8080/users";
        String username = "chathuranga";
        String password = "123";

        //set up the basic authentication header 
        String authorizationHeader = "Basic " + DatatypeConverter.printBase64Binary((username + ":" + password).getBytes());
  
        //setting up the request headers
        HttpHeaders requestHeaders = new HttpHeaders();
        requestHeaders.setContentType(MediaType.APPLICATION_JSON);
        requestHeaders.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        requestHeaders.add("Authorization", authorizationHeader);

        //setting up the request body
        User user = new User();
        user.setName("Sample User");
        user.setUsername("user1");
        user.setPassword("pass123");

        //request entity is created with request body and headers
        HttpEntity<User> requestEntity = new HttpEntity<>(user, requestHeaders);

        ResponseEntity<UserResponse> responseEntity = restTemplate.exchange(
                url,
                HttpMethod.POST,
                requestEntity,
                UserResponse.class
        );

        if(responseEntity.getStatusCode() == HttpStatus.OK){
           UserResponse user = responseEntity.getBody();
           System.out.println("user response retrieved ");
        }
    }