Red Hat Summit Red Hat Summit지원콘솔개발자평가판 시작연락처

이 콘텐츠는 선택한 언어로 제공되지 않습니다.

45.4. Returning entities with generic type information

Overview
링크 복사

There are occasions where the application needs more control over the MIME type of the returned object or the entity provider used to serialize the response. The JAX-RS javax.ws.rs.core.GenericEntity<T> class provides finer control over the serializing of entities by providing a mechanism for specifying the generic type of the object representing the entity.

Using a GenericEntity object
링크 복사

One of the criteria used for selecting the entity provider that serializes a response is the generic type of the object. The generic type of an object represents the Java type of the object. When a common Java type or a JAXB object is returned, the runtime can use Java reflection to determine the generic type. However, when a JAX-RS Response object is returned, the runtime cannot determine the generic type of the wrapped entity and the actual Java class of the object is used as the Java type.
To ensure that the entity provider is provided with correct generic type information, the entity can be wrapped in a GenericEntity<T> object before being added to the Response object being returned.
Resource methods can also directly return a GenericEntity<T> object. In practice, this approach is rarely used. The generic type information determined by reflection of an unwrapped entity and the generic type information stored for an entity wrapped in a GenericEntity<T> object are typically the same.

Creating a GenericEntity object
링크 복사

There are two ways to create a GenericEntity<T> object:
  1. Create a subclass of the GenericEntity<T> class using the entity being wrapped. Example 45.11, “Creating a GenericEntity<T> object using a subclass” shows how to create a GenericEntity<T> object containing an entity of type List<String> whose generic type will be available at runtime.

    Example 45.11. Creating a GenericEntity<T> object using a subclass

    import javax.ws.rs.core.GenericEntity;

List<String> list = new ArrayList<String>();
...
GenericEntity<List<String>> entity = 
  new GenericEntity<List<String>>(list) {};
Response response = Response.ok(entity).build();
    Copy to Clipboard Toggle word wrap
    Tip
    The subclass used to create a GenericEntity<T> object is typically anonymous.
  2. Create an instance directly by supplying the generic type information with the entity. Example 45.12, “Directly instantiating a GenericEntity<T> object” shows how to create a response containing an entity of type AtomicInteger.

    Example 45.12. Directly instantiating a GenericEntity<T> object

    import javax.ws.rs.core.GenericEntity;

AtomicInteger result = new AtomicInteger(12);
GenericEntity<AtomicInteger> entity = 
  new GenericEntity<AtomicInteger>(result, 
                                      result.getClass().getGenericSuperclass());
Response response = Response.ok(entity).build();
    Copy to Clipboard Toggle word wrap
맨 위로 이동
Red Hat logoGithubredditYoutubeTwitter

자세한 정보

평가판, 구매 및 판매

커뮤니티

Red Hat 문서 정보

Red Hat을 사용하는 고객은 신뢰할 수 있는 콘텐츠가 포함된 제품과 서비스를 통해 혁신하고 목표를 달성할 수 있습니다. 최신 업데이트를 확인하세요.

보다 포괄적 수용을 위한 오픈 소스 용어 교체

Red Hat은 코드, 문서, 웹 속성에서 문제가 있는 언어를 교체하기 위해 최선을 다하고 있습니다. 자세한 내용은 다음을 참조하세요.Red Hat 블로그.

Red Hat 소개

Red Hat은 기업이 핵심 데이터 센터에서 네트워크 에지에 이르기까지 플랫폼과 환경 전반에서 더 쉽게 작업할 수 있도록 강화된 솔루션을 제공합니다.

Theme

© 2025 Red Hat