如何在Retrofit库中使用Gson？

Question

我使用Retrofit发送请求并在android中收到响应，但是当我想要来自服务器的转换响应时它有问题总是给我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 （模特班）：

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配置：

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

你甚至不需要在这里制作自定义反序列化器。

完全摆脱UserDeserializer ，不需要它。 您的查询正在返回电影列表，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类将是：

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); 

问题不在于你没有错误地编写Deserializer （虽然你有，但它没关系，因为你不需要它， JsonParser 不是你怎么做的），但是默认的反序列化行为对你来说应该没问题。 使用上面的代码，它会工作得很好。

Answer 2

在Retrofit 2中它甚至更简单。 你的GitMovieApi课程：

interface MoviesApi {
    @GET("/3/movie/{movie}")
    Call<MovieList> getMovies(@Path("movie") String typeMovie,
                              @Query("api_key") String keyApi);
}

而且您只需要创建一个Retrofit对象，然后进行回调：

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(MOVIES_BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();
service = retrofit.create(MoviesApi.class);

Call<MovieList> mlc = service.getMovies(getArguments().getString(ARG_MOVIE_TYPE), getString(R.string.THE_MOVIE_DB_API_TOKEN));
mlc.enqueue(new Callback<MovieList>() {
        @Override
        public void onResponse(Call<MovieList> call, Response<MovieList> response) {
            movies = response.body().movieList;
        }

        @Override
        public void onFailure(Call<MovieList> call, Throwable t) {}
});