I have API which returns JSON in this format:
[
{ "shrtName": "abc", "validFrom": "2016-10-23", "name": "aaa", "version": 1 },
{ "shrtName": "def", "validFrom": "2016-11-20", "name": "bbb", "version": 1 },
{ "shrtName": "ghi", "validFrom": "2016-11-22", "name": "ccc", "version": 1 }
]
I have this code which reads API and returns it as a String. But I want to read this API and map it into the Java POJO class.
public String downloadAPI(){
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.set("API-Key", "4444444-3333-2222-1111-88888888");
HttpEntity<?> requestEntity = new HttpEntity<Object>(headers);
String URL = "https://aaaaaaa.io/api/v1/aaaaaaaaa?date=2015-04-04;
restTemplate.getMessageConverters().add(new StringHttpMessageConverter());
ResponseEntity<String> response = restTemplate.exchange(URL, HttpMethod.GET, requestEntity, String.class);
return response.getBody();
}
My questions:
1) Format of POJO?
2) Changes in my method (return type POJO instead of String)
Your JSON is an array that's why []
Create POJO
public class MyPOJO {
private String shrtName;
private Date validFrom;
private String name;
private int version;
}
Remove message converter and refactor restTemplate exchange method to
ResponseEntity<MyPOJO[].class> response = restTemplate.exchange(URL, HttpMethod.GET, requestEntity, MyPOJO[].class);
This is generic function that I use for GET requests
public <T> T getRequestAndCheckStatus(final String url, final Class<T> returnTypeClass,
final List<MediaType> mediaTypes,
final Map<String, String> headerParams,
final Map<String, Object> queryParams) throws Exception {
final HttpHeaders headers = new HttpHeaders();
headers.setAccept(mediaTypes);
setHeaderParamsIfExists(headers, headerParams);
final HttpEntity<String> requestEntity = new HttpEntity<>(headers);
UriComponentsBuilder uriBuilder = UriComponentsBuilder.fromHttpUrl(url);
setQueryParamsIfExists(uriBuilder, queryParams);
final ResponseEntity<T> entity = restTemplate
.exchange(getUrl(uriBuilder),
HttpMethod.GET,
requestEntity,
returnTypeClass);
Assert.assertEquals(HttpStatus.OK, entity.getStatusCode());
return entity.getBody();
}
private void setHeaderParamsIfExists(HttpHeaders headers, Map<String, String> headerParams) {
if(headerParams != null && !headerParams.isEmpty())
headerParams.entrySet()
.forEach(entry -> headers.set(entry.getKey(), entry.getValue()));
}
private void setQueryParamsIfExists(UriComponentsBuilder uriBuilder, Map<String, Object> queryParams) {
if(queryParams != null && !queryParams.isEmpty())
queryParams.entrySet()
.forEach(entry -> uriBuilder.queryParam(entry.getKey(), entry.getValue()));
}
private URI getUrl(UriComponentsBuilder uriBuilder) {
return uriBuilder.build().encode().toUri();
}
In your case you would call it by
getRequestAndCheckStatus("https://aaaaaaa.io/api/v1/aaaaaaaaa", MyPOJO[].class,
Collections.singletonList(MediaType.APPLICATION_JSON_UTF8),
new HashMap<String, String>(){{ put("API-Key", "4444444-3333-2222-1111-88888888"); }}),
new HashMap<String, Object>(){{ put("Date", "2015-04-04"); }});