**用于 Retrofit 2 **

在Web服务示例中定义监听程序：

public interface OnConnectionTimeoutListener {
    void onConnectionTimeout();
}

将拦截器添加到Web服务：

public WebServiceClient() {
    OkHttpClient client = new OkHttpClient();
    client.setConnectTimeout(10, TimeUnit.SECONDS);
    client.setReadTimeout(30, TimeUnit.SECONDS);
    client.interceptors().add(new Interceptor() {
        @Override
        public Response intercept(Chain chain) throws IOException {
            return onOnIntercept(chain);
        }
    });
    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .client(client)
            .build();
    webService = retrofit.create(WebService.class);
}

用try-catch块封装拦截代码，并在异常发生时通知侦听器：

private Response onOnIntercept(Chain chain) throws IOException {
    try {
        Response response = chain.proceed(chain.request());
        String content = UtilityMethods.convertResponseToString(response);
        Log.d(TAG, lastCalledMethodName + " - " + content);
        return response.newBuilder().body(ResponseBody.create(response.body().contentType(), content)).build();
    }
    catch (SocketTimeoutException exception) {
        exception.printStackTrace();
        if(listener != null)
            listener.onConnectionTimeout();
    }

    return chain.proceed(chain.request());
}

@Override
public void onFailure(Call call, Throwable t) {
    if(t instanceof SocketTimeoutException){
        message = "Socket Time out. Please try again.";
    }
}

如果有人带着Kotlin/Coroutines来到这里，面临同样的问题，请在您的协程作用域中添加一个错误处理程序：

CoroutineScope(Dispatchers.IO).launch(handler) {

而处理程序本身看起来像：

val handler = CoroutineExceptionHandler { _, exception ->
    Log.t("Network", "Caught $exception")
}

没有一个答案对我很有效，但它们把我引向了正确的方向。请看下面我在Kotlin是如何做到的。
您可以在ErrorInterceptor中抛出异常，然后在api调用函数中捕获它们：

class ErrorInterceptor : Interceptor {

    override fun intercept(chain: Chain): Response {

        val request = chain.request()

        try {
            val response = chain.proceed(request)
            val bodyString = response.body!!.string()

            return response.newBuilder()
                .body(bodyString.toResponseBody(response.body?.contentType()))
                .build()
        } catch (e: Exception) {
            when (e) {
                is SocketTimeoutException -> {
                    throw SocketTimeoutException()
                }

               // Add additional errors... //

            }
        }
    }

或者将异常与响应对象捆绑在一起;就像这样：

class ErrorInterceptor : Interceptor {

    override fun intercept(chain: Chain): Response {

        val request = chain.request()

        try {
            val response = chain.proceed(request)
            val bodyString = response.body!!.string()

            return response.newBuilder()
                .body(bodyString.toResponseBody(response.body?.contentType()))
                .build()
        } catch (e: Exception) {
            var msg = ""
            val interceptorCode: Int

            when (e) {
                is SocketTimeoutException -> {

                    msg = "Socket timeout error"
                    interceptorCode = 408

                }

               // Add additional errors... //

            }

             return Response.Builder()
                .request(request)
                .protocol(Protocol.HTTP_1_1)
                .code(interceptorCode)
                .message(msg)
                .body("{${e}}".toResponseBody(null)).build()
        }
    }
}

将ErrorInterceptor添加到您的okHttpClient：

okHttpClient.newBuilder()
                .addInterceptor(ErrorInterceptor())
                .connectTimeout(10, TimeUnit.SECONDS)
                 // ... //
                .build()

然后在存储库层中显示如下内容：

suspend fun makeAPIRequest(): Resource<ApiResponse> {

        return withContext(ioDispatcher) {

            var response: Response<ApiResponse>? = null

            try {
                response = getResponse()

                // Do additional ops on response here //

            } catch (e: Exception) {

                // Exceptions thrown in ErrorInterceptor will propagate here

            }
        }
    }

显然，异常确实被 Package 到RetrofitException中，以便您可以在失败方法中处理它。

这有点复杂，使用Retrofit你可以进行同步或异步的API调用。
如果你的端点返回void并且有回调，那么它是异步的;如果它返回了一些东西并且没有回调，那么它是同步的。
对于异步调用，在回调的onFailure(...)方法中会出现此异常。
对于同步调用，除非您将调用 Package 在try/catch中，否则您根本无法获得它。

try {
   // your synchronous call goes here  
} catch (RetrofitError error) {
   // handle errors
}

• 更新：以上答案适用于Retrofit 1.9。Retrofit 2.0已经改变了很多。如果你想知道现在的事情在Retrofit 2.0中是如何工作的，本文提供了一些指针http://inthecheesefactory.com/blog/retrofit-2.0/en *

我发布这个有两个原因：
1.我个人尝试过增加连接超时，但是，事实上，它并没有真正从根本上解决问题。此外，根据this post，用户不应该等待超过10秒。
1.在真实的应用程序中，我们宁愿尽最大努力以尽可能干净的方式实现解决方案。
这是我在Kotlin中提出的一个解决方案，它的灵感来自于@Olcay Ertaš提供的the answer，并结合了Google's recommended architecture用于Android应用程序。
1.创建TimeoutInterceptor接口：

interface TimeoutInterceptor : Interceptor

1.实现TimeoutInterceptor接口：

class TimeoutInterceptorImpl : TimeoutInterceptor {

     override fun intercept(chain: Interceptor.Chain): Response {
         if (isConnectionTimedOut(chain))
             throw SocketTimeoutException()
         return chain.proceed(chain.request())
     }

     private fun isConnectionTimedOut(chain: Interceptor.Chain): Boolean {
         try {
             val response = chain.proceed(chain.request())
             val content = response.toString()
             response.close()
             Log.d(tag, "isConnectionTimedOut() => $content")
         } catch (e: SocketTimeoutException) {
             return true
         }
         return false
     }
 }

1.在ApiService界面中，将TimeoutInterceptor添加到OkHttpClient构建器：

val okHttpClient = OkHttpClient.Builder()
         .addInterceptor(requestInterceptor)
         // Add timeout interceptor
         .addInterceptor(timeoutInterceptor)
         // Set a 5s custom connect timout
         .connectTimeout(5, TimeUnit.SECONDS)
         .build()

你可能已经注意到了，你可以设置一个自定义的连接超时，否则，根据documentation，它会被设置为10秒的默认值。
1.创建一个枚举类ConnectionState，它将提供一个枚举常量对象CONNECTION_TIMEOUT，该对象将进一步用于将适当的连接（或API调用）状态从EntityNetworkDataSource类传递到View类（如果您遵循Google的MVVM模式）：

enum class ConnectionState {
     CONNECTED, NOT_CONNECTED, CONNECTION_TIMEOUT
 }

1.假设您的EntityNetworkDataSource接口如下所示：

interface EntityNetworkDataSource {
     val fetchedEntity: LiveData<Entity>

     // Wrap your ConnectionState object in LiveData in order to be able to observe it in the View
     val connectionState: LiveData<ConnectionState>

     // Fetch `Entity` object from the network
     suspend fun fetchEntity(id: Int)
 }

1.在EntityNetworkDataSource实现类中，您可以在fetchEntity(id: Int)实现中正确捕获SocketTimeoutException，如下所示：

class EntityNetworkDataSourceImpl(
         private val apiService: ApiService
 ) : EntityNetworkDataSource {

     private val _fetchedEntity = MutableLiveData<Entity>()

     override val fetchedEntity: LiveData<Entity>
         get() = _fetchedEntity

     // We want to keep our MutableLiveData private because they can be changed.
     // So we want to be able to update them only from the inside of this class
     private val _connectionState = MutableLiveData<ConnectionState>()

     override val connectionState: LiveData<ConnectionState>
         get() = _connectionState

     override suspend fun fetchEntity(id: Int) {
         try {
             val fetchedEntity = apiService
                     .getEntity(id)
                     .await()

             // Convey the updated connection state to the observer View
             _connectionState.postValue(ConnectionState.CONNECTED)

             _fetchedEntity.postValue(fetchedEntity)
         } catch (e: SocketTimeoutException) {
             Log.e(tag, "Connection timeout. ", e)
             // Catch the SocketTimeoutException and post the updated connection state to the observer View
             _connectionState.postValue(ConnectionState.CONNECTION_TIMEOUT)
         }
     }
 }

同样的原则也适用于您想要拦截和捕获的任何连接异常。

Kotlin

如果要在Kotlin中使用Retrofit，请执行以下步骤：
定义Retrofit界面：

interface GitHubApi {

    @GET("/users/{userName}/repos")
    fun repos(@Path("userName") userName: String): Call<List<Repo>>
}

实施您的服务：

class Api(...) {

    private val baseUrl = "https://api.github.com"
    private val api: GitHubApi

    private fun loggingInterceptor(...): HttpLoggingInterceptor {...}

    private fun okHttpBuilder(): OkHttpClient {...}

    init {...}

    fun repos(
        userName: String,
        onSuccess: (list: List<Repo>?) -> Unit,
        onFailure: (message: String?) -> Unit): Future<Unit> {
        return runAsync(api.repos(userName), onSuccess, onFailure)
    }

    private fun <T> runAsync(
        call: retrofit2.Call<T>,
        onSuccess: (T?) -> Unit,
        onFailure: (message: String?) -> Unit) : Future<Unit> {
        return doAsync {
            try {
                val response = call.execute()
                when {
                    response.isSuccessful -> response.body()?.let {
                        onSuccess(it)
                    }
                    else -> {
                        onFailure(response.raw().message())
                    }
                }
            } catch (e: IOException) {
                if (e is SocketTimeoutException) {
                    onFailure("Response time out!")
                } else {
                    onFailure(e.message)
                }
            }
        }
    }
}

在您需要的位置呼叫您的服务：

Api().repos("olcayertas",
    onSuccess = {
        Log.d("MainActivity", "Response:\n" + toJson(it))
    },
    onFailure = {
        Log.e("MainActivity", "Error: $it")
    })

您可以在runAsync函数中处理任何您想要的异常。
您可以获得完整的工作示例here。