如何在Retrofit库中使用Gson？

Question

我使用Retrofit发送请求并在android中接收响应但是当我想要来自服务器的转换响应它有问题它总是给我Exception:

retrofit.RetrofitError: com.google.gson.JsonSyntaxException: 
               java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING

当服务器的响应应该给我电影列表,所以我需要把所有这些电影放在列表中.

Movie (型号类):

public class Movie {
    public Movie() {}
    @SerializedName("original_title")
    private String movieTitle;
    @SerializedName("vote_average")
    private String movieVoteAverage;
    @SerializedName("overview")
    private String movieOverview;
    ............  
}

GitMovieApi 类:

public interface GitMovieApi {
    @GET("/3/movie/{movie}")  
    public void getMovie(@Path("movie") String typeMovie,@Query("api_key") String  keyApi, Callback<Movie> response);    
}

RestAdapter 组态:

RestAdapter restAdapter = new RestAdapter.Builder()
                    .setLogLevel(RestAdapter.LogLevel.FULL)
                    .setConverter(new GsonConverter(new GsonBuilder().registerTypeAdapter(Movie.class, new UserDeserializer()).create()))
                    .setEndpoint("http://api.themoviedb.org")
                    .build(); 
                     GitMovieApi git = restAdapter.create(GitMovieApi.class);  
                git.getMovie("popular", "Keyapi", new Callback<Movie>() {
                @Override
                public void success(Movie movie, Response response) {
                    Toast.makeText(getActivity(), "s", Toast.LENGTH_LONG).show();
                }
                @Override
                public void failure(RetrofitError error) {
                    Toast.makeText(getActivity(), error.getMessage(), Toast.LENGTH_LONG).show();
                }
            });

UserDeserializer:

public class UserDeserializer implements JsonDeserializer<Movie> {
        @Override
        public Movie deserialize(JsonElement jsonElement, Type typeOF,
                                 JsonDeserializationContext context)
                throws JsonParseException {
            JsonElement userJson = new JsonParser().parse("results");
            return new Gson().fromJson(userJson, Movie.class);
        }
    }    

JSON(响应):

{
  "page": 1,
  "results": [
    {
      "adult": false,
      "backdrop_path": "/tbhdm8UJAb4ViCTsulYFL3lxMCd.jpg",
      "genre_ids": [
        53,
        28,
        12
      ],
      "id": 76341,
      "original_language": "en",
      "original_title": "Mad Max: Fury Road",
      "overview": "An apocalyptic story set in the furthest.",
      "release_date": "2015-05-15",
      "poster_path": "/kqjL17yufvn9OVLyXYpvtyrFfak.jpg",
      "popularity": 48.399601,
      "title": "Mad Max: Fury Road",
      "video": false,
      "vote_average": 7.6,
      "vote_count": 2114
    },
    {
      "adult": false,
      "backdrop_path": "/sLbXneTErDvS3HIjqRWQJPiZ4Ci.jpg",
      "genre_ids": [
        10751,
        16,
        12,
        35
      ],
      "id": 211672,
      "original_language": "en",
      "original_title": "Minions",
      "overview": "Minions Stuart.",
      "release_date": "2015-06-25",
      "poster_path": "/s5uMY8ooGRZOL0oe4sIvnlTsYQO.jpg",
      "popularity": 31.272707,
      "title": "Minions",
      "video": false,
      "vote_average": 6.8,
      "vote_count": 1206
    },     
],
  "total_pages": 11871,
  "total_results": 237415
}  

Answer 1

您甚至不需要在这里制作自定义解串器。

彻底摆脱UserDeserializer，没有必要。您的查询返回电影列表，因此请回调实际读取电影列表的对象：

public class MovieList {
    @SerializedName("results")
    List<Movie> movieList;
    // you can also add page, total_pages, and total_results here if you want
}

那么你的GitMovieApi课程将是：

public interface GitMovieApi {
    @GET("/3/movie/{movie}")  
    public void getMovie(@Path("movie") String typeMovie,
                @Query("api_key") String keyApi,
                Callback<MovieList> response);    
}

你的RestAdapter：

RestAdapter restAdapter = new RestAdapter.Builder()
                .setLogLevel(RestAdapter.LogLevel.FULL)
                .setConverter(new GsonConverter(new GsonBuilder()).create()))
                .setEndpoint("http://api.themoviedb.org")
                .build(); 
                 GitMovieApi git = restAdapter.create(GitMovieApi.class); 

问题不在于您写错了Deserializer（虽然，您写错了，但没关系，因为您不需要它，JsonParser不是您这样做的方式），而是默认的反序列化行为应该适合您。使用上面的代码，它会正常工作。