android - 服务生成器改造

Question

谁能帮我理解下面代码中的 createService 方法。我需要深入了解什么是方法的参数类 S 和底层代码

public class ServiceGenerator {

public static final String API_BASE_URL = Constant.BASE_URL;

private static OkHttpClient httpClient = new OkHttpClient();

private static Retrofit.Builder builder =
        new Retrofit.Builder()
                .baseUrl(API_BASE_URL)
                .addConverterFactory(GsonConverterFactory.create());

public static <S> S createService(Class<S> serviceClass) {
    httpClient.interceptors().add(new Interceptor() {
        @Override
        public Response intercept(Chain chain) throws IOException {
            Request original = chain.request();

            Request.Builder requestBuilder = original.newBuilder()
                    .header("cache-control","no-cache")
                    .method(original.method(), original.body());

            Request request = requestBuilder.build();
            return chain.proceed(request);
        }
    });

    Retrofit retrofit = builder.client(httpClient).build();
    return retrofit.create(serviceClass);
}

Answer 1

我自己找到了答案。整个 createservice 方法在此代码中并不是绝对必要的，没有 interceptor 声明也可以存在，如下所示。如果有人想为httpClient设置拦截器方法，比如cache-control、authorization token等，可以使用完整的代码块来设置它们。最简单的 createService 版本是

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

这里的“S”是类类型参数。它用于指定输出类型类与输入类相同。然后您可以在任何 Activity/fragment 中简单地使用此代码创建您自己的 api 接口(interface)

MyApiService myapiservice = ServiceGenerator.createService(MyApiServiceInterface.class)
Call<YourDataResponseClass> call = myapiService.getMyData(YourDataRequestClass);
call.enqueue ({.....remaining code})

定义你的MyApiService如下

public interface MyApiServiceInterface {
        /*Base url is already defined in service generator class*/
        @GET("/your/api/endpoint/")
        /*YourDataResponseClass and YourDataRequestClass are 
        pojo object notation of your request and response json*/
        YouDataResponseClass getMyData(
                @Body YourDataRequestClass request
        );
    }