Retrofit 分析

先上一个RetrofitHelper 使用kotlin的默认单例模式

object RetrofitHelper {
    private var mOkHttpClient: OkHttpClient? = null
    fun getGankApiService() = createApi(GankApi::class.java, "http://gank.io/")
    private fun  createApi(clazz: Class, baseUrl: String): T {
        if (mOkHttpClient == null)
            initOkHttpClient()
        val retrofit = Retrofit.Builder()
            .baseUrl(baseUrl)
            .client(mOkHttpClient!!)
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        return retrofit.create(clazz)
    }

    private fun initOkHttpClient() {
        val httpLoggingInterceptor = HttpLoggingInterceptor()
        httpLoggingInterceptor.level = HttpLoggingInterceptor.Level.BODY
        if (mOkHttpClient == null) {
            synchronized(RetrofitHelper::class.java) {
                if (mOkHttpClient == null) {
                    //val cache = Cache(File(.getCacheDir(), "HttpCache"), 1024 * 1024 * 1)
                    mOkHttpClient = OkHttpClient.Builder()
                        //.cache(cache)
                        .addInterceptor(httpLoggingInterceptor)
                        .retryOnConnectionFailure(true)
                        .connectTimeout(30, TimeUnit.SECONDS)
                        .writeTimeout(20, TimeUnit.SECONDS)
                        .readTimeout(20, TimeUnit.SECONDS)
                        .build()
                }
            }
        }
    }
}

Retrofit.java中create方法

 public  T create(final Class service) {
    Utils.validateServiceInterface(service);
    if (validateEagerly) {
      eagerlyValidateMethods(service);
    }
    return (T) Proxy.newProxyInstance(service.getClassLoader(), new Class[] { service },
        new InvocationHandler() {
          private final Platform platform = Platform.get();

          @Override public Object invoke(Object proxy, Method method, @Nullable Object[] args)
              throws Throwable {
            // If the method is a method from Object then defer to normal invocation.
            if (method.getDeclaringClass() == Object.class) {
              return method.invoke(this, args);
            }
            if (platform.isDefaultMethod(method)) {
              return platform.invokeDefaultMethod(method, service, proxy, args);
            }
            ServiceMethod serviceMethod =
                (ServiceMethod) loadServiceMethod(method);
            OkHttpCall