Develop Reference

Adding retrofit into android project

I want to try using Retrofit in a new Android project.
I have added the following to my build.gradle:
compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'
compile 'com.google.code.gson:gson:2.8.0'
I have a POJO called 'Turbine' which looks as follows:
public class Turbine {
String name;
}
I have my Endpoint service class:
import java.util.List;
import greenapps.objects.Turbine;
import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Path;
public interface GreenAppService {
#GET("turbines/{id}")
Call<List<Turbine>> turbine(#Path("id") String id);
}
In my main activity in android I have the following code (this is where I want to execute the call and get back my Turbine pojo object filled with data from the backend:
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
...
...
...
//Relevant snippet starts here
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(Constants.API_V1_ENDPOINT)
.build();
GreenAppService service = retrofit.create(GreenAppService.class);
Call<List<Turbine>> turbine = service.turbine("1");
turbine.enqueue(new Callback<Turbine>() {
#Override
public void onResponse(Call<Turbine> call, Response<Turbine> response) {
}
#Override
public void onFailure(Call<Turbine> call, Throwable t) {
}
});//Relevant snippet ends here
On the turbine.enqueue line I am getting the following error:
I presume the syntax here is wrong somehow, but I don't quite see what is causing the issue.
Also, once this works, how do I get my Turbine object? Is it a case of doing Turbine t = response.body();

Because you defined that you are waiting an Array of Turbine.
turbine.enqueue(new Callback<Turbine>()
to
turbine.enqueue(new Callback<ArrayList<Turbine>>()
also you need to update onResponse and onFailure methods with arraylist.
I strongly suggest you to apply singleton pattern for your GreenAppService object.
UPDATE
Here is an example of singleton pattern.
public final class WebService {
private static GreenAppService sInstance;
public static GreenAppService getInstance() {
if (sInstance == null) {
sInstance = new Retrofit
.Builder()
.baseUrl(Constants.API_V1_ENDPOINT)
.build();
}
return sInstance;
}
}
After that we call like
WebService
.getInstance()
.yourmethod()
.enqueue()

Easy way to add retrofit in your project with just one click. (one-time setup)
Retrofit zip
Extract the file and you will get the “Retrofit” folder inside.
Copy this folder following the Android Studio path
Android\Android Studio\plugins\android\lib\templates\other
Restart your Android Studio.
Select your project in which you want to add retrofit and find an option below.
Project > New > Other> Retrofit
You can see full blog here
https://medium.com/#mestri.vinayak.n/quick-install-retrofit-in-your-android-project-custom-template-a14a6adc77c2

Set the time out on Rest end points

I am trying to impose time limit on http end points.
In the example below, I am aiming that this method shall be executed before 5 seconds. If it is taking more time, I would like to throw exception and return error to client.
Spring : 4.1.7
Jersey 1.1.9
Code
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Response;
#Path("/pets")
#Component
public class PetsController {
#GET
#Produces({MediaTypeApi.JSON, MediaTypeApi.XML})
//Timeout of 5 secs
public List<Pet> getPets() {
//Return
}
}
Any idea to handle this in better way considering optimum utilization of threads.

EDIT
When writing this answer I didn't notice the version of Jersey OP is using. The async API was added in Jersey 2 therefore this answer is not an answer given OP's constraints.
EDIT 2
Apart from upgrading your Jersey libs you might consider migrating your api to Spring MVC and using their async API (available from Spring 3.2). Handling timeouts the Spring way (using the DeferredResult object):
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.context.request.async.DeferredResult;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
#RestController
#RequestMapping("/api")
public class AsyncController {
private static final TIMEOUT = 5000L;
private final AService aService;
#Inject
public AsyncController(final AService aService) {
this.aService = aService;
}
#RequestMapping(value = "/async-endpoint", method = RequestMethod.GET)
public DeferredResult<ResponseEntity<ADto>> asyncEndpoint() {
DeferredResult<ResponseEntity<ADto>> deferredResult = new DeferredResult<>(TIMEOUT);
CompletableFuture
.supplyAsync(() -> aService.aVeryExpensiveOperation())
.thenAccept(result -> {
deferredResult.setResult(new ResponseEntity<>(result, HttpStatus.OK));
})
.exceptionally(throwable -> {
deferredResult.setErrorResult(
throwable instanceof CompletionException ? throwable.getCause() : throwable);
return null;
});
return deferredResult;
}
}
ORIGINAL ANSWER:
There is an example in Jersey Asynchronous Server API Documentation doing exactly what you want:
import javax.ws.rs.container.Suspended;
import javax.ws.rs.container.TimeoutHandler;
import javax.ws.rs.core.Response;
import java.util.concurrent.TimeUnit;
#Path("/resource")
public class AsyncResource {
#GET
#Path("/timeoutAsync")
public void asyncGetWithTimeout(#Suspended final AsyncResponse asyncResponse) {
asyncResponse.setTimeoutHandler(new TimeoutHandler() {
#Override
public void handleTimeout(AsyncResponse asyncResponse) {
asyncResponse.resume(Response.status(Response.Status.SERVICE_UNAVAILABLE).entity("Operation time out.").build());
}
});
asyncResponse.setTimeout(5, TimeUnit.SECONDS);
new Thread(new Runnable() {
#Override
public void run() {
String result = veryExpensiveOperation();
asyncResponse.resume(result);
}
private String veryExpensiveOperation() {
return "Very Expensive Operation with Timeout";
}
}).start();
}
}
Please note that in a real life scenario you'd probably use a threadpool thread instead of creating it yourself like in this Jersey example

Fatal exception. Using Retrofit2-beta3 cannot retrieve data from apiUrl using retrofit2

Ive been doing this tutorial using Android Studio IDE.
The problem I have is that the tutorial was done with older libraries of gson and retrofit 1.8.0...
I was following along well with retrofit2.0-beta3 until I came upon this error that I cant seem to resolve..
It has something to do with this line...(this line is in my MainActivity.Java under onCreate())
SCService scService = SoundCloud.getService();
scService.getRecentTracks(new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date()), new Callback<List<Track>>() {
#Override
public void onResponse(Response<List<Track>> tracks) {
Log.d("TAG", "ONRESPONSE() - -- - some else wrong");
// response.isSuccess() is true if the response code is 2xx
if (tracks.isSuccess()) {
Log.d("TAG", "ONRESPONSE()_isSuccess? - -- - some else wrong");
List<Track> track = tracks.body();
loadTracks(track);
} else {
Log.d("TAG", "some else wrong");
}
}
#Override
public void onFailure(Throwable t) {
// handle execution failures like no internet connectivity
Log.d("Error", t.getMessage());
}
});
so I think that the problem starts with scService Interface..
import java.util.List;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.http.GET;
import retrofit2.http.Query;
interface SCService {
#GET("tracks?client_id=" + Config.CLIENT_ID)
public void getRecentTracks(#Query("created_at[from]") String date, Callback<List<Track>> cb);
}
Here is my Soundcloud class....
import retrofit2.Retrofit;
import retrofit2.Retrofit;
public class SoundCloud {
private static final Retrofit REST_ADAPTER = new Retrofit.Builder().baseUrl(Config.API_URL).build();
private static final SCService SERVICE = REST_ADAPTER.create(SCService.class);
public static SCService getService() {
return SERVICE;
}
}
This is the Config class didnt think it would be needed...
public class Config {
public static final String CLIENT_ID = "c85f6828ae5eaf5981937ead09ef1b45";
public static final String API_URL = "https://api.soundcloud.com/";
}
I have been at this the whole day, Any help would be much appreciated..

It could be few things, but most likely the problem is that Gson converter is no longer automatically registered with retrofit and thus your code doesn't know how to get you object from Json. I.e. in retrofit2 you need to register Gson like:
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("http://api.nuuneoi.com/base/")
.addConverterFactory(GsonConverterFactory.create(gson))
.build();
Take a look at this article: Retrofit 2 changes, Custom Gson Object (in the middle of the page)

Can't verify mock method call from RxJava Subscriber

I'm trying to unit test presenter in my Android app. Method I'm trying to test looks like this:
#Override
public boolean loadNextPage() {
if (!mIsLoading) {
mIsLoading = true;
if (mViewReference.get() != null) {
mViewReference.get().showProgress();
}
mService.search(mSearchQuery, ++mCurrentPage)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(itemsPage -> {
mIsLoading = false;
mTotalPages = itemsPage.getPagination().getTotalPages();
if (mViewReference.get() != null) {
mViewReference.get().showMovies(itemsPage.getItems());
}
},
error -> {
mIsLoading = false;
Log.d(LOG_TAG, error.toString());
});
}
return mTotalPages == 0 || mCurrentPage < mTotalPages;
}
mService is Retrofit interface and mService.search() method returns RxJava's Observable<SearchResults>. My unit test code looks like this:
package mobi.zona.presenters;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.runners.MockitoJUnitRunner;
import java.util.ArrayList;
import java.util.List;
import com.example.api.Service;
import com.example.model.Movie;
import com.example.model.SearchResults;
import com.example.views.MoviesListView;
import rx.Observable;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;
#RunWith(MockitoJUnitRunner.class)
public class SearchPresenterTest {
#Mock
Service mService;
#Mock
MoviesListView mMoviesListView;
#Test
public void testLoadNextPage() throws Exception {
String searchQuery = "the hunger games";
SearchResults searchResults = new SearchResults();
List<Movie> movies = new ArrayList<>();
searchResults.setItems(movies);
when(mService.search(searchQuery, 1)).thenReturn(Observable.just(new SearchResults()));
MoviesListPresenter presenter = new SearchPresenter(mZonaService, mMoviesListView, searchQuery);
presenter.loadNextPage();
verify(mService, times(1)).search(searchQuery, 1);
verify(mMoviesListView, times(1)).showProgress();
verify(mMoviesListView, times(1)).showMovies(movies);
}
}
The problem is the third verify(mMoviesListView, times(1)).showMovies(movies); line - it allways fails. Whem I'm trying to debug this test I see that control flow never goes into .subscribe(itemPage - {.... I think that it's something related to the fact that I'm subscribing on Schedulers.io() thread, but have no idea on how to fix this. Any ideas?
EDIT 1:
Changed the presenter to take Scheduler's as constructor parameters. Changed test to look like this:
#Test
public void testLoadNextPage() throws Exception {
String searchQuery = "the hunger games";
SearchResults searchResults = new SearchResults();
List<Movie> movies = new ArrayList<>();
searchResults.setItems(movies);
when(mZonaService.search(searchQuery, 1)).thenReturn(Observable.just(new SearchResults()));
MoviesListPresenter presenter = new SearchPresenter(mZonaService, mMoviesListView, searchQuery,
Schedulers.test(), Schedulers.test());
presenter.loadNextPage();
verify(mZonaService, times(1)).search(searchQuery, 1);
verify(mMoviesListView, times(1)).showProgress();
verify(mMoviesListView, times(1)).showMovies(movies);
}
Still getting this test failure message:
Wanted but not invoked:
mMoviesListView.showMovies([]);
-> at com.example.presenters.SearchPresenterTest.testLoadNextPage(SearchPresenterTest.java:46)
However, there were other interactions with this mock:
mMoviesListView.showProgress();
-> at com.example.presenters.SearchPresenter.loadNextPage(SearchPresenter.java:41)

In my apps interactors/use-cases/model (mService in your case) is responsible for specifying Scheduler for the operation (since it knows better what kind of operation it does).
So, move your subscribeOn to mService. After that your mock will work fine.
Going deeper, if now you'll want to test mService I would recommend you to make it "dependent" on Scheduler. In other words - add Sheduler as a constructor parameter.
public class MyService {
private final Scheduler taskScheduler;
public MyService(Scheduler taskScheduler) {
this.taskScheduler = taskScheduler;
}
// ...
public Observable<Something> query() {
return someObservable.subscribeOn(taskScheduler);
}
}
Then, in tests you can use Schedulers.immediate() and for actual app Schedulers.io() (or whatever you like, really).

How to use custom PolicySpi

I'm trying to implement a custom java.security.Permission type, which should be checked at runtime (so no policy file, but in code). This checking is done by a java.security.Policy. I understood I should implement my own java.security.PolicySpi for this.
I cannot find any explanation on how to initialise and use a PolicySpi, or is there a better way to do this?

Checking permissions
In your question you stated that you then want to check the permission with java.security.Policy, but without using a spi.policy file.
From the PolicySpi API, you can see that a PolicySpi object features 4 methods:
engineGetPermissions(CodeSource codesource)
engineGetPermissions(ProtectionDomain domain)
engineImplies(ProtectionDomain domain, Permission permission)
engineRefresh()
However, you might not need PolicySpi as there are easier solutions to check permissions.
See:
Security Manager vs Access Controller
AccessController usage
Since you haven't specified what kind of permission you will grant, I will assume it is a permission concerning a java.security.CodeSource object.
To check all current permissions for a file:
public static void main(String[] args) {
CodeSource source;
try {
source = new CodeSource(new URL("file:/c:/*"), (java.security.cert.Certificate[]) null);
Policy policy = Policy.getPolicy();
System.out.println(policy.getPermissions(source));
} catch (IOException e) {
e.printStackTrace();
}
}
A nice example for the SecurityManager checkPermission() is this tutorial.
For checking specific FilePermissions, you can use:
FilePermission perm = new FilePermission("path/file", "read");
AccessController.checkPermission(perm);
Granting permissions
Granting permissions at runtime can be done with java.lang.RuntimePermission.
For other examples of how to grant permissions to a file, I suggest you read the following:
Access Control Mechanisms and Algorithms
Configuring spi.policy files
Security Managers and Permissions
That should bring you a long way! Good luck!

The previous answer lists alternatives to using PolicySpi (and more generally custom Policy implementations ). This answer will instead give a simplistic example on how a PolicySpi implementation can actually be used as a replacement of the system-default Policy.
Author a JCA Provider.
package com.example;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.Provider;
public final class TestProvider extends Provider {
private static final long serialVersionUID = 5544432861418770903L;
public TestProvider() {
super("TestProvider", 1, "TestProvider 1.0");
AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
putService(new TestPolicySpiService(this));
return null;
});
}
}
Author the sole Service descriptor encapsulated by the provider.
package com.example;
import java.security.Policy.Parameters;
import java.security.PolicySpi;
import java.security.Provider;
import java.security.Provider.Service;
import java.util.Collections;
final class TestPolicySpiService extends Service {
TestPolicySpiService(Provider p) {
super(p, "Policy", "TestPolicy", PolicySpi.class.getName(), Collections.emptyList(), Collections.emptyMap());
}
#Override
public PolicySpi newInstance(Object constructorParameter) {
Parameters policyParams = null;
if (constructorParameter instanceof Parameters) {
policyParams = (Parameters) constructorParameter;
}
return new TestPolicySpi(policyParams);
}
#Override
public boolean supportsParameter(Object parameter) {
return parameter instanceof Parameters;
}
}
Author the actual service (the PolicySpi implementation in this case) that the service descriptor produces.
package com.example;
import java.security.Permission;
import java.security.Policy.Parameters;
import java.security.PolicySpi;
import java.security.ProtectionDomain;
final class TestPolicySpi extends PolicySpi {
TestPolicySpi(Parameters policyParams) {}
#Override
protected boolean engineImplies(ProtectionDomain domain, Permission permission) {
// deny unconditionally
return false;
}
}
Register the provider either statically, by modifying the security.provider.n properties in JAVA_HOME/lib/security/java.security, or programmatically, via java.security.Security.addProvider(Provider) / java.security.Security.insertProviderAt(Provider, int).
Replace the default Policy.
package com.example;
import java.security.NoSuchAlgorithmException;
import java.security.Policy;
public class Main {
public static void main(String... args) throws NoSuchAlgorithmException {
// the following assumes that the provider has been statically registered
Policy.setPolicy(Policy.getInstance("TestPolicy", null));
System.setSecurityManager(new SecurityManager());
// test
System.out.println(System.getProperty("user.home")); // should raise AccessControlException
}
}
Is there a better way to do this?
There certainly is a less involved way, as long as the consequent tight coupling between application and policy does not irk you too badly: Just subclass Policy directly and pass an instance of your implementation to Policy.setPolicy(Policy).
Further reading:
Java Cryptography Architecture (JCA) Reference Guide
How to Implement a Provider in the Java Cryptography Architecture
Standard Algorithm Name Documentation for JDK 8
Troubleshooting Security

As of Java 6, the default implementation for PolicySpi is sun.security.provider.PolicySpiFile. You can get inspired from the source code of PolicySpiFile:
package sun.security.provider;
import java.security.CodeSource;
import java.security.Permission;
import java.security.PermissionCollection;
import java.security.Policy;
import java.security.PolicySpi;
import java.security.ProtectionDomain;
import java.security.URIParameter;
import java.net.MalformedURLException;
/**
* This class wraps the PolicyFile subclass implementation of Policy
* inside a PolicySpi implementation that is available from the SUN provider
* via the Policy.getInstance calls.
*
*/
public final class PolicySpiFile extends PolicySpi {
private PolicyFile pf;
public PolicySpiFile(Policy.Parameters params) {
if (params == null) {
pf = new PolicyFile();
} else {
if (!(params instanceof URIParameter)) {
throw new IllegalArgumentException
("Unrecognized policy parameter: " + params);
}
URIParameter uriParam = (URIParameter)params;
try {
pf = new PolicyFile(uriParam.getURI().toURL());
} catch (MalformedURLException mue) {
throw new IllegalArgumentException("Invalid URIParameter", mue);
}
}
}
protected PermissionCollection engineGetPermissions(CodeSource codesource) {
return pf.getPermissions(codesource);
}
protected PermissionCollection engineGetPermissions(ProtectionDomain d) {
return pf.getPermissions(d);
}
protected boolean engineImplies(ProtectionDomain d, Permission p) {
return pf.implies(d, p);
}
protected void engineRefresh() {
pf.refresh();
}
}