set autorization basic with username and password + resttemplate
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();
}