Retrofit 创建

不错的rxjava＋retrofit文章
Retrofit + OkHttp3 自定义全局Header和Cookie管理
RxJava 与 Retrofit 结合的最佳实践
RxJava+Retrofit
扔物线

（1）module里build.gradle需要引用：

compile 'io.reactivex:rxandroid:1.1.0'
compile 'io.reactivex:rxjava:1.1.2'
compile 'com.squareup.retrofit2:retrofit:2.0.1'
compile 'com.squareup.retrofit2:converter-gson:2.0.1'
compile 'com.squareup.retrofit2:adapter-rxjava:2.0.1'
compile 'com.squareup.okhttp3:logging-interceptor:3.0.0-RC1'

log拦截器

HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.setLevel(HttpLoggingInterceptor.Level.HEADERS).setLevel(HttpLoggingInterceptor.Level.BODY);

** header 拦截器**

   Interceptor headerInterceptor = new Interceptor() 
{
           @Override
      
  public Response intercept(Chain chain) throws IOException {
  
                     Request original = chain.request();

           
  Request request = original.newBuilder()
  
                .addHeader("**", "**")
     
                .addHeader("**", "**")

                .method(original.method(), original.body())
                    .build();

            
return chain.proceed(request);
   
     }
    };

public interface UserInterface {  
  @GET("top250") 
   Observable<HttpResult<List<Subject>>> getTopMovie(@Query("start") int start, @Query("count") int count);}

Retrofit retrofit = new Retrofit.Builder()        
.baseUrl("https://baidu.com/")        
.addConverterFactory(GsonConverterFactory.create(gson))        
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())        
.client(okHttpClient())    
.build();
UserInterface uesrinterface = retrofit.create(UserInterface.class);

** NetworkInterceptor Interceptor 讲解**
如果你没有使用缓存，用哪种都一样。 NetworkInterceptor是针对需要真实请求网络的请求的拦截器 Interceptor则会拦截所有请求，包括读取缓存的请求