I'm trying to create an Interceptor in the event that the API I'm using goes down, which has happened when I tried to make an API call on Postman only for it to return a 504 error.
This is the OkHttpClient I have for now. I set it to 5 seconds only for testing purposes.
val client = OkHttpClient.Builder()
.connectTimeout(5, TimeUnit.SECONDS)
.writeTimeout(5, TimeUnit.SECONDS)
.readTimeout(5, TimeUnit.SECONDS)
.addInterceptor(object : Interceptor {
override fun intercept(chain: Interceptor.Chain): okhttp3.Response {
val response = chain.proceed(chain.request())
when (response.code()) {
504 -> {
//Show Bad Request Error Message
}
}
return response
}
})
.build()
searchRetrofit = Retrofit.Builder()
.addConverterFactory(MoshiConverterFactory.create(moshi))
.baseUrl(URL)
.client(client)
.build()
Later in the code, I use Retrofit's execute() method to make a synchronous call to the API. The execute() line and val response = chain.proceed(chain.request()) crashes my app if the API service is down or if it's taking too long to retrieve results. I get the java.net.SocketTimeoutException error.
What can I do to prevent my app from crashing when the API service I'm using is down? What can I add to the Interceptor or should I surround my execute() call in a try catch statement?
Proper solution would be to use enqueue instead of execute. synchronous network calls are almost always a bad idea, because you don't want to block the calling thread. to use enqueue you should do
call.enqueue(object : Callback<SomeResponse> {
override fun onFailure(call: Call<SomeResponse>?, t: Throwable?) {
// This code will be called when your network call fails with some exception
// SocketTimeOutException etc
}
override fun onResponse(call: Call<SomeResponse>?, response: Response<SomeResponse>?) {
// This code will be called when response is received from network
// response can be anything 200, 504 etc
}
})
If you must use execute then at the very least you will have to enclose your execute call in try catch
try{
call.execute()
}
catch(e: Exception){
// Process any received exception (SocketTimeOutEtc)
}
Related
I am writing an android application using Kotlin ,Retrofit ,OKHttp and Rxjava when make a call to my API in order to add a new user to database i get the following message in logcat:
I/system_server: oneway function results will be dropped but finished with status OK and parcel size 4
The problem is that nothing happens no user is added in fact the API does not receive any requests from my app even thought i have the appropriate permissions and a android:usesCleartextTraffic="true" annotation in my AndroidManifest.xml.
By putting println() in various places in the code I was able to confirm that the function responsible for making the call is in fact executed but code responsible for handling response is never called and no error is reported.
Here is the code of above mentioned function:
private fun addUser(user: UserDataObject) {
val client = OkHttpClient.Builder()
.addInterceptor(BasicAuthInterceptor("admin", "admin")) // temporarily hardcoded
.build()
val requestInterface = Retrofit.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.addCallAdapterFactory(RxJava3CallAdapterFactory.create())
.client(client)
.build().create(GetData::class.java)
myCompositeDisposable?.add(
requestInterface.addUser(user)
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(Schedulers.io())
.subscribe(this::handleResponse, this::onError)
)
}
and the code of the interface:
interface GetData {
#POST("/api/some/API/URL")
fun addUser(#Body user: UserDataClass) : Completable}
also ( just in case ) the code of interceptor:
class BasicAuthInterceptor(username: String, password: String): Interceptor {
private var credentials: String = Credentials.basic(username, password)
override fun intercept(chain: Interceptor.Chain): okhttp3.Response {
var request = chain.request()
request = request.newBuilder().header("Authorization", credentials).build()
return chain.proceed(request)
}
}
Can you please tell me why is my app not able to communicate with API ?
While searching for answer on the internet i found this question so I gather that it has something to do with selinux permissions but this doesn't help me at all since I'm just a beginner.
I'm using Retrofit with OkHttp Interceptor to work with API.
Interceptor adding cookie header to each request.
Interceptors code:
class AddCookiesInterceptor: Interceptor {
#Inject
lateinit var cookiesDao: CookiesDao
init {
App.getAppComponent().inject(this)
}
#SuppressLint("CheckResult")
override fun intercept(chain: Interceptor.Chain): Response {
val builder = chain.request().newBuilder()
cookiesDao.getAll()
.subscribeOn(Schedulers.io())
.subscribe { cookies ->
builder.addHeader("Cookie", "JWT=" + cookies.jwt)
}
return chain.proceed(builder.build())
}
}
While debuging i see, that interceptor updates request and adds cookie header with value, but when server reachs the request it returns an error (400 http code auth again).
if i manualy add Header into request like this
#GET("/api.tree/get_element/")
#Headers("Content-type: application/json", "X-requested-with: XMLHttpRequest", "Cookie: jwt_value")
fun getElementId(): Maybe<ResponseBody>
Api returns 200 http code and it works.
Your code is not working because you are adding the header asynchronously, this is a "timeline" of what's happening in your flow:
init builder -> ask for cookies -> proceed with chain -> receive cookies dao callback -> add header to builder which has been already used
What you need to do is retrieve the cookies synchronously, to accomplish this you can use the BlockingObseervable and get something like this.
Using a synchronous function won't cause any trouble since the interceptor is already running on a background thread.
#SuppressLint("CheckResult")
override fun intercept(chain: Interceptor.Chain): Response {
val builder = chain.request().newBuilder()
val cookies = cookiesDao.getAll().toBlocking().first()
builder.addHeader("Cookie", "JWT=" + cookies.jwt)
return chain.proceed(builder.build())
}
I have the following code where I'm making a PUT request to Sendgrid. Unfortunately, the code is not working. It's using OkHttpClient. Can someone please help?
val client = OkHttpClient()
val body: RequestBody = RequestBody.create(
"application/json; charset=utf-8".toMediaTypeOrNull(),
"{\"list_ids\":[\"X\"]}"
)
val request: Request = Request.Builder()
.url("https://api.sendgrid.com/v3/marketing/contacts")
.put(body)
.addHeader("authorization", "Bearer SG.X")
.addHeader("content-type", "application/json")
.build()
val response = client.newCall(request).execute()
I get the following error
FATAL EXCEPTION: main
Process: com.sumizeit.sumizeit, PID: 9738
android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1598)
at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:115)
at java.net.Inet6AddressImpl.lookupAllHostAddr(Inet6AddressImpl.java:103)
at java.net.InetAddress.getAllByName(InetAddress.java:1152)
at okhttp3.Dns$Companion$DnsSystem.lookup(Dns.kt:49)
This exception is thrown when application attempts to perform a networking operation in the main thread. Use below code in your onCreate to avoid this error then put your code
val policy = StrictMode.ThreadPolicy.Builder()
.permitAll().build()
StrictMode.setThreadPolicy(policy)
As the NetworkOnMainThreadException says, you're trying to perform a network request on the UI thread, which is not allowed.
You must do this in a background thread. Following your code, you could make some small changes:
client.newCall(request).enqueue(object : Callback {
override fun onFailure(call: Call, e: IOException) {
// Handle error
}
override fun onResponse(call: Call, response: Response) {
if (response.isSuccessful) {
// Success!
} else {
// Handle response not successful
}
}
})
If you are going to update your UI, just be sure to go back to main thread when updating the views, by calling for example
runOnUiThread { /* update views safely */ }
in the case your code is being executed in a Activity.
I'm using a custom Interceptor along with Retrofit client in my Android app, that throws an Exception under some specific circumstances. I'm trying to make it work using Kotlin coroutines.
The problem is that I'm unable to handle the before mentioned error, since in the moment the exception is thrown from within the Interceptor instance, it crashes the whole app instead of being caught in the coroutine's try/catch statement. While I was using the Rx implementation, the exception was flawlessly propagated to the onError callback where I was able to handle it the way I needed.
I guess this is somehow related to the underlying threads that are being used for the network call, please see the logs below from the place where the call is made, from the interceptor just before throwing the exception, and the stacktrace:
2019-11-04 17:17:34.515 29549-29729/com.app W/TAG: Running thread: DefaultDispatcher-worker-1
2019-11-04 17:17:45.911 29549-29834/com.app W/TAG: Interceptor thread: OkHttp https://some.endpoint.com/...
2019-11-04 17:17:45.917 29549-29834/com.app E/AndroidRuntime: FATAL EXCEPTION: OkHttp Dispatcher
Process: com.app, PID: 29549
com.app.IllegalStateException: Passed refresh token can\'t be used for refreshing the token.
at com.app.net.AuthInterceptor.intercept(AuthInterceptor.kt:33)
What am I supposed to do in order to be able to catch and handle this exception from the Interceptor correctly? Am I missing something?
You should subclass IOException and use that to send information from your interceptors to your calling code.
We consider other exceptions like IllegalStateException to be application crashes and do not send them over thread boundaries because we don’t want to burden most callers with catching them.
You may catch the exception in your custom Interceptor and return an empty response with some specific message and code. I have implemented a custom Interceptor to handle the situation like when you do not have or slow internet connection etc... Actually coroutine's suspend functions throws exception when dealing with network calls. In my experience, you can follow 2 approaches. 1. wrap your all network call in try...catch or 2. create a custom Interceptor and handle exceptions there and return some specific response.
Approach 1:
try {
webservice.login(username, password)
} catch (e: Exception) {
//...
}
Approach 2:
Create a custom Interceptor and handle exception there.
class LoggingInterceptor : Interceptor {
#Throws(Exception::class)
override fun intercept(chain: Interceptor.Chain): Response {
val request = chain.request()
try {
val response = chain.proceed(request)
val bodyString = response.body()!!.string()
return response.newBuilder()
.body(ResponseBody.create(response.body()?.contentType(), bodyString))
.build()
} catch (e: Exception) {
e.printStackTrace()
var msg = ""
when (e) {
is SocketTimeoutException -> {
msg = "Timeout - Please check your internet connection"
}
is UnknownHostException -> {
msg = "Unable to make a connection. Please check your internet"
}
is ConnectionShutdownException -> {
msg = "Connection shutdown. Please check your internet"
}
is IOException -> {
msg = "Server is unreachable, please try again later."
}
is IllegalStateException -> {
msg = "${e.message}"
}
else -> {
msg = "${e.message}"
}
}
return Response.Builder()
.request(request)
.protocol(Protocol.HTTP_1_1)
.code(999)
.message(msg)
.body(ResponseBody.create(null, "{${e}}")).build()
}
}
}
I have created gist for complete implementation of LoggingInterceptor with print logs of request and response. LoggingInterceptor
I dont know what exactly you need, but understood like this:
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.addInterceptor(new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request request = chain.request();
okhttp3.Response response = chain.proceed(request);
// todo deal with the issues the way you need to
if (response.code() == SomeCode) {
//do something
return response;
}
return response;
}
})
.build();
Retrofit.Builder builder = new Retrofit.Builder()
.baseUrl(url)
.client(okHttpClient)
.addConverterFactory(GsonConverterFactory.create());
Retrofit retrofit = builder.build();
I have an API which returns 200, 202, 4xx based on different scenarios. When I get a 202, I am supposed to make the same API until I get a 200 or 4xx. I tried using doOnErrorNext, onError, onNext. I was not able to crack the problem
Observable<MyPOJO> makeAPI();
Observable<MyPOJO> makeAPIImpl(){
makeAPI().doOnErrorNext(/*how to I access the error code here*/);
makeAPI().doOnNext(/*given that 202 is a success code, I expected it to come here, but it goes to Error because of JSON Mapping*/);
}
doOnErrorNext -> I was able to make the API call again but then it would happen for all the error scenarios which I dont want
I have checked multiple answers regarding this, but nobody has solved this combination specifically and am unable to incorporate other answers to my use case.
I would suggest you use OkHttp and use an interceptor to retry your request, something along these lines (this is from one of my apps in Kotlin, but it should give you the idea):
inner class ExpiredSessionInterceptor : Interceptor {
override fun intercept(chain: Interceptor.Chain): Response {
val request = chain.request()
val response = chain.proceed(request)
if (response.code() == 202) {
val newRequest = request.newBuilder().build()
return chain.proceed(newRequest)
} else {
return response;
}
}
}
then
val httpClientBuilder = OkHttpClient.Builder()
httpClientBuilder.addInterceptor(ExpiredSessionInterceptor())
val retrofit: Retrofit = Retrofit.Builder()
.baseUrl(SERVER_ENDPOINT_URL)
.addConverterFactory(GsonConverterFactory.create(gson))
.addCallAdapterFactory(RxJava2CallAdapterFactory.createWithScheduler(Schedulers.io()))
.client(httpClientBuilder.build())
.build()