The simple way of calling authenticated requests in retrofit style

Dependencies

• Retrofit 1.9.0
• RxJava 1.0.15
• appcompat-v7: 23.1.0

Min SDK Version: 9

Example:

Your services using retrofit:

public interface SomeService {
    @GET("/some/path")
    Observable<ResultObject> someRxJavaCall();
}

Your services using retroauth:

@Authentication(accountType = R.string.auth_account_type, tokenType = R.string.auth_token_type)
public interface SomeService {
    @Authenticated
    @GET("/some/path")
    Observable<ResultObject> someAuthenticatedRxJavaCall();
}

What does it do?

If you call a request method, annotated with the authenticated annotation, it'll do the following steps:

• Step 1: Checks if there already is an account in the Android AccountManager. If not, it'll open a LoginActivity (you choose which). If there already is an account, go on with step 2, If there's more than one account open an Dialog to pick an account.
• Step 2: Tries to get the authentication token from the (choosen) account to add it to the request header. If there is no valid token, your LoginActivity could open with the pre-filled accounts username. After login go to Step 1.
• Step 3: Sends the actual request
• Step 4: If the request fails with an 401 (by default, but changeable) it invalidates the used token in the Android AccountManager and continues with step 1.

Sequence Diagrams can be found in the DIAGRAMS.md file

How to use it?

Add it as dependency:

compile 'eu.unicate.android:retroauth:1.0.4'

1. Create 3 strings in your strings.xml

i.e.

<resources>
    ...
	<!-- String for the account type you want to use in your app -->
	<string name="auth_account_type">eu.unicate.retroauth.demo.account</string>
	<!-- String for the type of token you're using. -->
	<string name="auth_token_type">eu.unicate.retroauth.demo.token</string>
	<!-- String for the Action to open the activity to login if necessary -->
	<string name="authentication_action">eu.unicate.auth.action.AUTH</string>
	...
</resources>

2. Create an Activity (or use one you already have) where the user can login. This Activity must extend from AuthenticationActivity and call finalizeAuthentication when the authentication finished

i.e. (see Demo for an example)

public class LoginActivity extends AuthenticationActivity {
   ...
   private void someLoginMethod() {
        String user;
        String token;
        ... // do login work here and make sure, that you provide at least a user and a token String
        // the Token type is the one you defined in Step 1
        Account account = createOrGetAccount(user);
        storeToken(account, getString(R.string.auth_token_type), token);
        // add multiple tokens: storeToken(account, getString(R.string.auth_token_type2), token2);
        // store some additional userdata (optionally)
        storeUserData(account, "key_for_some_user_data", "very-important-userdata");
        // finishes the activity and set this account to the "current-active" one
        finalizeAuthentication(account);
   }
   ...
}

Make sure your LoginActivity has the intent filter in the manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest>
...
       <activity android:name=".LoginActivity">
           <intent-filter>
               <!-- THIS MUST BE THE SAME STRING AS DEFINED IN STEP 1 (sadly the resource string cannot be used for that) -->
               <action android:name="eu.unicate.auth.action.AUTH"/>
               <category android:name="android.intent.category.DEFAULT"/>
           </intent-filter>
       </activity>
...
</manifest>

3. Implement a very basic AuthenticationService

public class SomeAuthenticationService extends AuthenticationService {
	@Override
	public String getLoginAction(Context context) {
	    // this is used only to provide the action for the LoginActivity to open
		return context.getString(R.string.authentication_action); // <=  This is the String provided in Step 1
	}
}

Provide a authenticator.xml:

<account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"
					   android:accountType="@string/auth_account_type"  <= This is the String provided in Step 1
					   android:icon="@mipmap/ic_launcher"
					   android:smallIcon="@mipmap/ic_launcher"
					   android:label="@string/app_name" />

Add the Service to the Manifest:

        ...
        <service
            android:name=".SomeAuthenticationService"
            android:process=":auth"
            android:exported="false">
            <intent-filter>
                <action android:name="android.accounts.AccountAuthenticator"/>
            </intent-filter>
            <meta-data
                android:name="android.accounts.AccountAuthenticator"
                android:resource="@xml/authenticator"/>
        </service>
        ...
    </application>
</manifest>

4. Create your REST interface

• Add authentication information to it:

@Authentication(accountType = R.string.auth_account_type, tokenType = R.string.auth_token_type)
public interface SomeAuthenticatedService {
    @GET("/some/path")
    Observable<ResultObject> someUnauthenticatedCall();

    @Authenticated
    @GET("/some/path")
    Observable<ResultObject> someAuthenticatedRxJavaCall();

    // or
    @Authenticated
    @GET("/some/path")
    JsonElement someAuthenticatedBlockingCall();

    // or
    @Authenticated
    @GET("/some/path")
    void someAuthenticatedAsyncCall(Callback<JsonElement> callback);
}

5. Create your Service

// create your RestAdapter just use AuthRestAdapter instead of RestAdapter
// it provides all functionality as the original one
AuthRestAdapter restAdapter = new AuthRestAdapter.Builder()
   .setEndpoint("http://some.api.endpoint")
   .setLogLevel(RestAdapter.LogLevel.FULL)
   .build();
...
service = restAdapter.create(context, TokenInterceptor.BEARER_TOKENINTERCEPTOR, SomeAuthenticatedService.class);
// If you want the Login to open, make sure your context is an activity. If you're calling this
// from a service with a Service-context or even with the application context, the login won't open.
// This is because the addAccount Method requires an Activity to be able to open the (Login)Activity

That's it.

Have fun with it!

Pull requests are welcome

Since I am the only one working on that, I would like to know your opinion and/or your suggestions. Please feel free to create Pull requests!

LICENSE

Copyrights 2015 André Tietz

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

<http://www.apache.org/licenses/LICENSE-2.0>

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.