谷歌图书api改造

Question

我正在尝试将谷歌图书 API 与Retrofit一起使用，它返回一个空结果。

这是网址：https : //www.googleapis.com/books/v1/volumes? q
=9781451648546

在改造中，我有一个界面：

public interface IServiceEndPoint {
  @GET("https://www.googleapis.com/books/v1/volumes?q=9781451648546")
  Call<BookList> getBooks();
}

在我webservice class我有以下方法：

public void getBooks(final Callback<BookList> callback){
  IServiceEndPoint endPoint = mRetrofit.create(IServiceEndPoint.class);
  Call<BookList> call = endPoint.getBooks();
  call.enqueue(callback);
}

在activity class我有方法：

private void getBooks(){
  WebserviceHelper.getmInstance().getBooks(new Callback<BookList>() {
    @Override
    public void onResponse(Call<BookList> call, Response<BookList> response) {
      mBooks = response.body().getResults();
      mBookAdapter.update(mBooks);
    }

    @Override
    public void onFailure(Call<BookList> call, Throwable t) {

    }
  });
}

我有一个 Java 类Book和BookList。

public class Book implements Serializable {

    @SerializedName("id")
    private String id;
    @SerializedName("title")
    private String title;
public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

public class BookList extends Book implements Serializable {
    @SerializedName("results")
    private List<Book> results;

    public List<Book> getResults() {
        return results;
    }

    public void setResults(List<Book> results) {
        this.results = results;
    }
}

在我添加的清单文件中

使用权限 android:name="android.permission.INTERNET

mBooks返回空值，我该如何解决？
谢谢你。

编辑： shuvro的回答帮助我纠正了这个问题。我还忘记在我的 Book 类中包含 volumeInfo。我的书类现在看起来如下：

public class Book implements Serializable {

    @SerializedName("id")
    private String id;

    private VolumeInfo volumeInfo;

    public VolumeInfo getVolumeInfo() {
        return volumeInfo;
    }

    public void setVolumeInfo(VolumeInfo volumeInfo) {
        this.volumeInfo = volumeInfo;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

}

另外我创建了类volumeInfo：

public class VolumeInfo {
    private String title;
    private String subtitle;
    private String publisher;
    private String description;

    public String getSubtitle() {
        return subtitle;
    }

    public void setSubtitle(String subtitle) {
        this.subtitle = subtitle;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

感谢大家的帮助！

Answer 1

在您的 gradle 文件中添加两个依赖项。

compile 'com.squareup.retrofit2:retrofit:2.1.0'
compile 'com.squareup.retrofit2:converter-gson:2.1.0'

创建一个类，让我们使用ServiceGenerator，你的类应该是这样的

public class ServiceGenerator {


    private static OkHttpClient.Builder httpClient = new OkHttpClient.Builder();

    private static Retrofit.Builder builder =
            new Retrofit.Builder()
                    .baseUrl("https://www.googleapis.com/books/v1/")
                    .addConverterFactory(GsonConverterFactory.create());

    public static <S> S createService(Class<S> serviceClass) {
        Retrofit retrofit = builder.client(httpClient.build()).build();
        return retrofit.create(serviceClass);
    }
}

现在你像这样声明你的界面

public interface IServiceEndPoint {
  @GET("volumes")
  Call<BookList> getBooks(@Query("q") String id);
}

现在在 Activity 或 Fragment 中，以这种方式使用 Retrofit

IServiceEndPoint serviceEndPoint = ServiceGenerator.createService(IServiceEndPoint.class)

Call<BookList> call = serviceEndPoint.getBooks("9781451648546");

 call.enqueue(new Callback<BookList>() {
        @Override
        public void onResponse(Call<BookList> call, Response<BookList> response) {
         //do whatever you want to do 
        }

        @Override
        public void onFailure(Call<BookList> call, Throwable t) {

        }
    });