Spring RestTemplate and generic types ParameterizedTypeReference collections like List

An Abstract controller class requires List of objects from REST. While using Spring RestTemplate its not mapping it to required class instead it returns Linked HashMAp

 public List<T> restFindAll() {

    RestTemplate restTemplate = RestClient.build().restTemplate();
    ParameterizedTypeReference<List<T>>  parameterizedTypeReference = new ParameterizedTypeReference<List<T>>(){};
    String uri= BASE_URI +"/"+ getPath();

    ResponseEntity<List<T>> exchange = restTemplate.exchange(uri, HttpMethod.GET, null,parameterizedTypeReference);
    List<T> entities = exchange.getBody();
    // here entities are List<LinkedHashMap>
    return entities;


If I use,

ParameterizedTypeReference<List<AttributeInfo>>  parameterizedTypeReference = 
    new ParameterizedTypeReference<List<AttributeInfo>>(){};
    ResponseEntity<List<AttributeInfo>> exchange =
  restTemplate.exchange(uri, HttpMethod.GET, null,parameterizedTypeReference);

It works fine. But can not put in all subclasses, any other solution.


I worked around this using the following generic method:

public <T> List<T> exchangeAsList(String uri, ParameterizedTypeReference<List<T>> responseType) {
    return restTemplate.exchange(uri, HttpMethod.GET, null, responseType).getBody();

Then I could call:

List<MyDto> dtoList = this.exchangeAsList("http://my/url", new ParameterizedTypeReference<List<MyDto>>() {});

This did burden my callers with having to specify the ParameterizedTypeReference when calling, but meant that I did not have to keep a static mapping of types like in vels4j’s answer 

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