DeepLinkDispatch

DeepLinkDispatch provides a declarative, annotation-based API to define application deep links.

You can register an Activity to handle specific deep links by annotating it with @DeepLink and a URI. DeepLinkDispatch will parse the URI and dispatch the deep link to the appropriate Activity, along with any parameters specified in the URI.

Example

Here's an example where we register SampleActivity to pull out an ID from a deep link like example://example.com/deepLink/123. We annotated with @DeepLink and specify there will be a parameter that we'll identify with id.

@DeepLink("example://example.com/deepLink/{id}")
public class SampleActivity extends Activity {
  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Intent intent = getIntent();
    if (intent.getBooleanExtra(DeepLink.IS_DEEP_LINK, false)) {
      Bundle parameters = intent.getExtras();
      String idString = parameters.getString("id");
      // Do something with idString
    }
  }
}

Multiple Deep Links

Sometimes you'll have an Activity that handles several kinds of deep links:

@DeepLink({"foo://example.com/deepLink/{id}", "foo://example.com/anotherDeepLink"})
public class MainActivity extends Activity {
  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Intent intent = getIntent();
    if (intent.getBooleanExtra(DeepLink.IS_DEEP_LINK, false)) {
      Bundle parameters = intent.getExtras();
      String idString = parameters.getString("id");
      // Do something with idString
    }
  }
}

DeepLinkHandler Annotations

You can annotate a Kotlin object that is extending com.airbnb.deeplinkdispatch.handler.DeepLinkHandler with an @DeepLink annotation.

@DeepLink("foo://example.com/handlerDeepLink/{param1}?query1={queryParameter}")
object ProjectDeepLinkHandler : DeepLinkHandler<ProjectDeepLinkHandlerArgs>() {
    override fun handleDeepLink(parameters: ProjectDeepLinkHandlerArgs) {
        /**
         * From here any internal/3rd party navigation framework can be called the provided args.
         */
    }
}

data class ProjectDeepLinkHandlerArgs(
    @DeeplinkParam("param1", DeepLinkParamType.Path) val number: Int,
    @DeeplinkParam("query1", DeepLinkParamType.Query) val flag: Boolean?,
)

DeepLinkDispatch will then call the handleDeepLink function in your handler with the path placeholders and queryParameters converted into an instance of the specified type class.

Query parameter conversion is supported for nullable and non nullable versions of Boolean,Int, Long,Short,Byte,Double,Float and String as well as the same types in Java. For other types see: Type conversion

This will give compile time safety, as all placeholders and query parameters specified in the template inside the @DeepLink annotation must be present in the arguments class for the processor to pass. This is also true the other way around as all fields in the arguments class must be annotated and must be present in the template inside the annotation.

From this function you can now call into any internal or 3rd party navigation system without any Intent being fired at all and with type safety for your arguments.

Note: Even though they must be listed in the template and annotation, argument values annotated with DeepLinkParamType.Query can be null as they are allowed to not be present in the matched url.

Type conversion

If you want to support the automatic conversions of types other than Boolean,Int,Long,Short,Byte, Double,Float and String in deep link argument classes you can add support by adding your own type converters in the DeepLinkDelegate class that you are instantiating.

Type conversion is handled via a lambda that you can set in the DeepLinkDelegate constructor.

All type converters you want to add get added to an instance of TypeConverters which then in turn gets returned by the lambda. This way you can add type converters on the fly while the app is running (e.g. if you just downloaded a dynamic feature which supports additional types).

There is an example of this in the sample app for this. Here is a brief overview:

TypeConverters typeConverters = new TypeConverters();
typeConverters.put(ColorDrawable.class, value -> {
  switch (value.toLowerCase()) {
    case "red":
      return new ColorDrawable(0xff0000ff);
  }
});

Function0<TypeConverters> typeConvertersLambda = () -> typeConverters;

DeepLinkDelegate deepLinkDelegate = new DeepLinkDelegate(
  ...
  typeConvertersLambda,
  ...);

Type conversion errors

If a url parameter cannot be converted to the specified type, the system will -- by default -- set the value to 0 or null, depending on if the type is nullable. However this behavior can be overwritten by implementing a lambda Function3<DeepLinkUri, Type, String, Integer> and setting it to typeConversionErrorNullable and/or typeConversionErrorNonNullable via the DeepLinkDelegate constructor. When called, the lambda will let you know about the matching DeepLinkUri template, the type and the value that was tried to type convert so you can also log these events.

Method Annotations

You can also annotate any public static method with @DeepLink. DeepLinkDispatch will call that method to create the Intent and will use it when starting your Activity via that registered deep link:

@DeepLink("foo://example.com/methodDeepLink/{param1}")
public static Intent intentForDeepLinkMethod(Context context) {
  return new Intent(context, MainActivity.class)
      .setAction(ACTION_DEEP_LINK_METHOD);
}

If you need access to the Intent extras, just add a Bundle parameter to your method, for example:

@DeepLink("foo://example.com/methodDeepLink/{param1}")
public static Intent intentForDeepLinkMethod(Context context, Bundle extras) {
  Uri.Builder uri = Uri.parse(extras.getString(DeepLink.URI)).buildUpon();
  return new Intent(context, MainActivity.class)
      .setData(uri.appendQueryParameter("bar", "baz").build())
      .setAction(ACTION_DEEP_LINK_METHOD);
}

If you're using Kotlin, make sure you also annotate your method with @JvmStatic. companion objects will not work, so you can use an object declaration instead:

object DeeplinkIntents {
  @JvmStatic 
  @DeepLink("https://example.com")
  fun defaultIntent(context: Context, extras: Bundle): Intent {
    return Intent(context, MyActivity::class.java)
  }
}

If you need to customize your Activity backstack, you can return a TaskStackBuilder instead of an Intent. DeepLinkDispatch will call that method to create the Intent from the TaskStackBuilder last Intent and use it when starting your Activity via that registered deep link:

@DeepLink("http://example.com/deepLink/{id}/{name}")
public static TaskStackBuilder intentForTaskStackBuilderMethods(Context context) {
  Intent detailsIntent =  new Intent(context, SecondActivity.class).setAction(ACTION_DEEP_LINK_COMPLEX);
  Intent parentIntent =  new Intent(context, MainActivity.class).setAction(ACTION_DEEP_LINK_COMPLEX);
  TaskStackBuilder  taskStackBuilder = TaskStackBuilder.create(context);
  taskStackBuilder.addNextIntent(parentIntent);
  taskStackBuilder.addNextIntent(detailsIntent);
  return taskStackBuilder;
}

If, depending on app state or parameter values you have to either just start an Intent or a TaskStackBuilder, you can return an instance of DeepLinkMethodResult, which can have any. The system will pick whichever value is not null but will prefer the TaskStackBuilder if both are not null.

@DeepLink("dld://host/methodResult/intent")
public static DeepLinkMethodResult intentOrTaskStackBuilderViaDeeplinkMethodResult(Context context) {
  TaskStackBuilder taskStackBuilder = null;
  Intent intent = null;
  if (someState) {
    Intent detailsIntent = new Intent(context, SecondActivity.class);
    Intent parentIntent = new Intent(context, MainActivity.class);
    taskStackBuilder = TaskStackBuilder.create(context);
    taskStackBuilder.addNextIntent(parentIntent);
    taskStackBuilder.addNextIntent(detailsIntent);
  } else {
    intent = new Intent(context, MainActivity.class);
  }
  return new DeepLinkMethodResult(intent, taskStackBuilder);
}

Query Parameters

Query parameters are parsed and passed along automatically, and are retrievable like any other parameter. For example, we could retrieve the query parameter passed along in the URI foo://example.com/deepLink?qp=123:

@DeepLink("foo://example.com/deepLink")
public class MainActivity extends Activity {
  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Intent intent = getIntent();
    if (intent.getBooleanExtra(DeepLink.IS_DEEP_LINK, false)) {
      Bundle parameters = intent.getExtras();
      if (parameters != null && parameters.getString("qp") != null) {
        String queryParameter = parameters.getString("qp");
        // Do something with the query parameter...
      }
    }
  }
}

Configurable path segment placeholders

Configurable path segment placeholders allow your to change configured elements of the URL path at runtime without changing the source of the library where the deeplink is defined. That way a library can be used in multiple apps that are still uniquely addressable via deeplinks. They are defined by encapsulating an id like this <some_id> and are only allowed as a path segment (between two slashes. /:

@DeepLink("foo://cereal.com/<type_of_cereal>/nutritional_info")
public static Intent intentForNutritionalDeepLinkMethod(Context context) {
  return new Intent(context, MainActivity.class)
      .setAction(ACTION_DEEP_LINK_METHOD);
}

If you do this you do have to provide a mapping (at runtime) for which values are allowed for creating a match. This is done when you new the DeeplinkDelegate class like:

@DeepLinkHandler({ AppDeepLinkModule.class, LibraryDeepLinkModule.class })
public class DeepLinkActivity extends Activity {
  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Configure a map for configurable placeholders if you are using any. If you do a mapping
    // has to be provided for that are used
    Map configurablePlaceholdersMap = new HashMap();
    configurablePlaceholdersMap.put("type_of_cereal", "obamaos");
    // DeepLinkDelegate, LibraryDeepLinkModuleRegistry and AppDeepLinkModuleRegistry
    // are generated at compile-time.
    DeepLinkDelegate deepLinkDelegate = 
        new DeepLinkDelegate(new AppDeepLinkModuleRegistry(), new LibraryDeepLinkModuleRegistry(), configurablePlaceholdersMap);
    // Delegate the deep link handling to DeepLinkDispatch. 
    // It will start the correct Activity based on the incoming Intent URI
    deepLinkDelegate.dispatchFrom(this);
    // Finish this Activity since the correct one has been just started
    finish();
  }
}

This app will now match the Url foo://cereal.com/obamaos/nutritional_info to the intentForNutritionalDeepLinkMethod method for that app. If you build another app and set type_of_cereal to captnmaccains that apps version of the intentForNutritionalDeepLinkMethod would be called when when opening foo://cereal.com/captnmaccains/nutritional_info

If you are using configurable path segment placeholders, a mapping has to be provided for every placeholder used. If you are missing one the app will crash at runtime.

Empty configurable path segment placeholders mapping

A mapping can be to an empty string, in that case the element is just ignored. In the above example if configurablePlaceholdersMap.put("type_of_cereal", ""); is defined foo://cereal.com/nutritional_info would map to calling the intentForNutritionalDeepLinkMethod method. An empty configurable path segment placeholder is not allowed as the last path element in an URL!

Callbacks

You can optionally register a BroadcastReceiver to be called on any incoming deep link into your app. DeepLinkDispatch will use LocalBroadcastManager to broadcast an Intent with any success or failure when deep linking. The intent will be populated with these extras:

• DeepLinkHandler.EXTRA_URI: The URI of the deep link.
• DeepLinkHandler.EXTRA_SUCCESSFUL: Whether the deep link was fired successfully.
• DeepLinkHandler.EXTRA_ERROR_MESSAGE: If there was an error, the appropriate error message.

You can register a receiver to receive this intent. An example of such a use is below:

public class DeepLinkReceiver extends BroadcastReceiver {
  private static final String TAG = "DeepLinkReceiver";

  @Override public void onReceive(Context context, Intent intent) {
    String deepLinkUri = intent.getStringExtra(DeepLinkHandler.EXTRA_URI);
    if (intent.getBooleanExtra(DeepLinkHandler.EXTRA_SUCCESSFUL, false)) {
      Log.i(TAG, "Success deep linking: " + deepLinkUri);
    } else {
      String errorMessage = intent.getStringExtra(DeepLinkHandler.EXTRA_ERROR_MESSAGE);
      Log.e(TAG, "Error deep linking: " + deepLinkUri + " with error message +" + errorMessage);
    }
  }
}

public class YourApplication extends Application {
  @Override public void onCreate() {
    super.onCreate();
    IntentFilter intentFilter = new IntentFilter(DeepLinkHandler.ACTION);
    LocalBroadcastManager.getInstance(this).registerReceiver(new DeepLinkReceiver(), intentFilter);
  }
}

Custom Annotations

You can reduce the repetition in your deep links by creating custom annotations that provide common prefixes that are automatically applied to every class or method annotated with your custom annotation. A popular use case for this is with web versus app deep links:

// Prefix all app deep link URIs with "app://airbnb"
@DeepLinkSpec(prefix = { "app://airbnb" })
// When using tools like Dexguard we require these annotations to still be inside the .dex files
// produced by D8 but because of this bug https://issuetracker.google.com/issues/168524920 they
// are not so we need to mark them as RetentionPolicy.RUNTIME.
@Retention(RetentionPolicy.RUNTIME)
public @interface AppDeepLink {
  String[] value();
}

You can use placeholders (like in paths) in the scheme and host section of prefixes listed in the DeepLinkSpec. e.g. if you want to match both http and https you can define it like this:

// Match all deeplinks which a scheme staring with "http".
@DeepLinkSpec(prefix = { "http{url_scheme_suffix}://airbnb.com")
@Retention(RetentionPolicy.CLASS)
public @interface WebDeepLink {
  String[] value();
}

You will get the value of url_scheme_suffix which -- in this case would be "" for http and "s" when https is used -- in the extras bundle of your annotated method. If you want to limit which values are accepted, you can do that directly within the placeholder by defining it with allowed values like this: http{url_scheme_suffix(|s)}://airbnb.com. In this case valid values would be "" and "s" (http and https). Values are pipe(|) separated, there can only be one (...) section per placeholder and it has to be at the end of the placeholder.

// Match all deeplinks which a scheme staring with "http".
@DeepLinkSpec(prefix = { "http{url_scheme_suffix(|s)}://{prefix(|www.)}airbnb.{domain(com|de)}")
@Retention(RetentionPolicy.CLASS)
public @interface WebDeepLink {
  String[] value();
}

The above code would match URLs that start with http or https, are for airbnb.com or airbnb.de or www.airbnb.com and www.airbnb.de. They would e.g. not match airbnb.ro.

// This activity is gonna handle the following deep links:
// "app://airbnb/view_users"
// "http://airbnb.com/users"
// "http://airbnb.com/user/{id}"
// "https://airbnb.com/users"
// "https://airbnb.com/user/{id}"
@AppDeepLink({ "/view_users" })
@WebDeepLink({ "/users", "/user/{id}" })
public class CustomPrefixesActivity extends AppCompatActivity {
    //...
}

This can be very useful if you want to use it with country prefxes in hostnames e.g.

// Match all deeplinks that have a scheme starting with http and also match any deeplink that
// starts with .airbnb.com as well as ones that are only airbnb.com
@DeepLinkSpec(prefix = { "http{url_scheme_suffix}://{country_prefix}.airbnb.com",
 "http{url_scheme_suffix}://airbnb.com")
@Retention(RetentionPolicy.CLASS)
public @interface WebDeepLink {
  String[] value();
}

which saves you from defining a lot prefixes.

Usage

Add to your project build.gradle file (Latest version is ):

dependencies {
  implementation 'com.airbnb:deeplinkdispatch:x.x.x'
}

DeeplinkDispatch supports three ways to run the annotation processor dependin on which one you choose the setup is slightly different.

KSP

When using Kotlin we strongly suggest to use KSP as it can bring major speed improvements.

To run the processor via KSP you first have to apply the KSP plugin. Add the dependency to the build.gradle file of your main project:

buildscript {

    apply from: rootProject.file("dependencies.gradle")

    repositories {
        google()
        gradlePluginPortal()
    }
    dependencies {
        classpath "com.google.devtools.ksp:com.google.devtools.ksp.gradle.plugin:<ksp-version>"
    }
}

Apply the plugin in the build.gradle file of the project you want to use it:

plugins {
  id("com.google.devtools.ksp")
}

and don't forget the dependency to the annotation procesor and DeepLinkDispatch itself:

dependencies {
  implementation 'com.airbnb:deeplinkdispatch:x.x.x'
  ksp 'com.airbnb:deeplinkdispatch-processor:x.x.x'
}

Note: When using KSP (you have ksp 'com.airbnb:deeplinkdispatch-processor:x.x.x' in your dependencies) at least one Kotlin source file must be present in the project or no output will be generated!

As an example the main sample app is set up using KSP.

Kapt

If your project is already setup for Kotlin the only thing you have to add is the plugin:

plugins {
  id("kotlin-kapt")
}

and don't forget the dependency to the annotation procesor and DeepLinkDispatch itself:

dependencies {
  implementation 'com.airbnb:deeplinkdispatch:x.x.x'
  kapt 'com.airbnb:deeplinkdispatch-processor:x.x.x'
}

As an example the sample-kapt-library is set up using Kapt

Java annotation processor

Just add the dependency to DeepLinkDispatch and to the annotation processor:

dependencies {
  implementation 'com.airbnb:deeplinkdispatch:x.x.x'
  annotationProcessor 'com.airbnb:deeplinkdispatch-processor:x.x.x'
}

As an example the sample-library is set up using the Java annotation processor

When this is done, create your deep link module(s) (new on DeepLinkDispatch v3). For every class you annotate with @DeepLinkModule, DeepLinkDispatch will generate a "Registry" class, which contains a registry of all your @DeepLink annotations.

/** This will generate a AppDeepLinkModuleRegistry class */
@DeepLinkModule
public class AppDeepLinkModule {
}

Optional: If your Android application contains multiple modules (eg. separated Android library projects), you'll want to add one @DeepLinkModule class for every module in your application, so that DeepLinkDispatch can collect all your annotations in one "Registry" class per module:

/** This will generate a LibraryDeepLinkModuleRegistry class */
@DeepLinkModule
public class LibraryDeepLinkModule {
}

Create any Activity (eg. DeepLinkActivity) with the scheme you'd like to handle in your AndroidManifest.xml file (using foo as an example):

<activity
    android:name="com.example.DeepLinkActivity"
    android:theme="@android:style/Theme.NoDisplay">
    <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />
        <data android:scheme="foo" />
    </intent-filter>
</activity>

Annotate your DeepLinkActivity with @DeepLinkHandler and provide it a list of @DeepLinkModule annotated class(es):

@DeepLinkHandler({ AppDeepLinkModule.class, LibraryDeepLinkModule.class })
public class DeepLinkActivity extends Activity {
  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // DeepLinkDelegate, LibraryDeepLinkModuleRegistry and AppDeepLinkModuleRegistry
    // are generated at compile-time.
    DeepLinkDelegate deepLinkDelegate = 
        new DeepLinkDelegate(new AppDeepLinkModuleRegistry(), new LibraryDeepLinkModuleRegistry());
    // Delegate the deep link handling to DeepLinkDispatch. 
    // It will start the correct Activity based on the incoming Intent URI
    deepLinkDelegate.dispatchFrom(this);
    // Finish this Activity since the correct one has been just started
    finish();
  }
}

of

@DeepLinkHandler({ AppDeepLinkModule.class, LibraryDeepLinkModule.class })
public class DeepLinkActivity extends Activity {
  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Configure a map for configurable placeholders if you are using any. If you do a mapping
    // has to be provided for that are used
    Map configurablePlaceholdersMap = new HashMap();
    configurablePlaceholdersMap.put("your_values", "what should match");
    // DeepLinkDelegate, LibraryDeepLinkModuleRegistry and AppDeepLinkModuleRegistry
    // are generated at compile-time.
    DeepLinkDelegate deepLinkDelegate = 
        new DeepLinkDelegate(new AppDeepLinkModuleRegistry(), new LibraryDeepLinkModuleRegistry(), configurablePlaceholdersMap);
    // Delegate the deep link handling to DeepLinkDispatch. 
    // It will start the correct Activity based on the incoming Intent URI
    deepLinkDelegate.dispatchFrom(this);
    // Finish this Activity since the correct one has been just started
    finish();
  }
}

if you use configurable path segments

Upgrading

When upgrading to 5.x+ you may experience some breaking API changes. Read about them here.

Incremental annotation processing

You must update your build.gradle to opt into incremental annotation processing. When enabled, all custom deep link annotations must be registered in the build.gradle (pipe (|) separated), otherwise they will be silently ignored.

Examples of this configuration are as follows:

Standard

javaCompileOptions {
  annotationProcessorOptions {
    arguments = [
      'deepLink.incremental': 'true',
      'deepLink.customAnnotations': 'com.airbnb.AppDeepLink|com.airbnb.WebDeepLink'
    ]
  }
}

Kotlin kapt

kapt {
  arguments {
    arg("deepLink.incremental", "true")
    arg("deepLink.customAnnotations", "com.airbnb.AppDeepLink|com.airbnb.WebDeepLink")
  }
}

KSP

KSP is always incremental and you always have to provide the list of deepLink.customAnnotation if you have any or they will not be processed.

ksp {
  arg("deepLink.incremental", "true")
  arg("deepLink.customAnnotations", "com.airbnb.AppDeepLink|com.airbnb.WebDeepLink")
}

Performance

Starting with v5 DeeplinkDispatch is designed to be very fast in resolving deep links even if there are a lot of them. To ensure we do not regress from this benchmark tests using androidx.benchmark were added.

It is testing the ScaleTestActivity in the sample-benchmarkable-library which has 2000 deep links. For those on a Pixel 2 running Android 11 we expect the following results:

Started running tests

benchmark:        11,716 ns DeeplinkBenchmarks.match1
benchmark:       139,375 ns DeeplinkBenchmarks.match500
benchmark:     2,163,907 ns DeeplinkBenchmarks.newRegistry
benchmark:        23,035 ns DeeplinkBenchmarks.match1000
benchmark:       152,969 ns DeeplinkBenchmarks.match1500
benchmark:       278,906 ns DeeplinkBenchmarks.match2000
benchmark:       162,604 ns DeeplinkBenchmarks.createResultDeeplink1
benchmark:        11,774 ns DeeplinkBenchmarks.parseDeeplinkUrl
Tests ran to completion.

As you can see it takes us about 2ms to create the registry with 2000 entries. A lookup can be done in sub 1ms usually and createResult, which includes the lookup for the match1 case plus actually calling the method that was annotated, can be done in under 0.2ms.

The performance tests can be run from Android Studio or via gradle by running ./gradlew sample-benchmark:connectedCheck (with a device connected). The outoput can be found in sample-benchmark/build/outputs/connected_android_test_additional_output/.

Notes

• Starting with DeepLinkDispatch v3, you have to always provide your own Activity class and annotate it with @DeepLinkHandler. It's no longer automatically generated by the annotation processor.
• Intent filters may only contain a single data element for a URI pattern. Create separate intent filters to capture additional URI patterns.
• Please refer to the sample app for an example of how to use the library.

Snapshots of the development version are available in Sonatype's snapshots repository.

To access the snapshots add this to your build.gradle file:

repositories {
    maven {
        url "https://oss.sonatype.org/content/repositories/snapshots/"
    }
}

Generated deep links Documentation

You can tell DeepLinkDispatch to generate text a document with all your deep link annotations, which you can use for further processing and/or reference. Note: Passing a fully qualified file path string as an argument to any compilation task will cause the cache key to be non-relocateable from one machine to another. In order to do that, add to your build.gradle file:

tasks.withType(JavaCompile) {
  options.compilerArgs << "-AdeepLinkDoc.output=${buildDir}/doc/deeplinks.txt"
}

When using Kotlin Kapt

kapt {
  arguments {
    arg("deepLinkDoc.output", "${buildDir}/doc/deeplinks.txt")
  }
}

and if you are using KSP

ksp {
  arg("deepLinkDoc.output", "${buildDir}/doc/deeplinks.txt")
}

The documentation will be generated in the following format:

* {DeepLink1}\n|#|\n[Description part of javadoc]\n|#|\n{ClassName}#[MethodName]\n|##|\n
* {DeepLink2}\n|#|\n[Description part of javadoc]\n|#|\n{ClassName}#[MethodName]\n|##|\n

You can also generate the output in a much more readable Markdown format by naming the output file *.md (e.g. deeplinks.md). Make sure that your Markdown viewer understands tables.

Matching and edge cases

Deeplink Dispatchs matching algo is designed to match non ambiguous structured URI style data very fast but because of the supported featureset it comes with some edge cases.

We organize the URI data (of all URIs that are in your app) in a tree structure that is created per module. The URI is dissolved into that tree structure and inserted into that graph at build time. We do not allow duplicates inside the tree at built time and having them will fail the build. However this is currently only guaranteed for each module not across modules.)

At runtime we traverse the graph for each module to find the correct action to undertake. The algo just walks the input URI until the last element and never backtracks inside the graph. The children of each element are checked for matches in alphabetic order:

elements without any variable element -> elements containing placeholders -> elements that are a configurable path segment

Edge cases

• Duplicates can exist between modules. Only the first one found will be reported as a match. Modules are processed in the order the module registries are listed in your DeepLinkDelegate creation.
• Placeholders can lead to duplications at runtime e.g. dld://airbnb/dontdupeme will match both @Deeplink('dld://airbnb/{qualifier}dupeme') and @Deeplink('dld://airbnb/dontdupeme'). They can both be defined in the same module as they are not identical. If they are defined in the same module the algo will match @Deeplink('dld://airbnb/dontdupeme') as it would check litereal matches before looking at elements containing placeholders. If they are not defined in the same module the one defined in the registry listed first in DeeplinkDelegate will be matched.
• Configurable path segments can lead to duplicates. e.g. dld://airbnb/obamaos/cereal will match both @Deeplink('dld://airbnb/obamaos/cereal/') and @Deeplink('dld://airbnb/<brand>/cereal') if <brand> is configured to be obamaos. The same match rules as mentioned before apply here.
• Configurable path segments can have empty values e.g. <brand> can be set to "" in the previous example. Which would then match dld://airbnb/cereal. If a deeplink like that is defined already somewhere else the same match rules as mentioned before apply to which match actually gets found.
• Because of limitations of the algo the last path element (the item behind the last slash) cannot be a configurable path segment with it's value set to "". Currently the system will allow you to do this but will not correctly match in that case.

Proguard/R8 Rules

The Proguard/R8 rules mandatory for teh lib are defined in the proguard-rules.pro in deeplinkdispatch. However they are already included via consumerProguardFiles so there is nothing you have to do to include them.

Please note however that you must add your own Proguard/R8 rules to keep Custom annotations you have used. For example:

-keep @interface your.package.path.deeplink.<annotation class name>
-keepclasseswithmembers class * {
    @your.package.path.deeplink.<annotation class name> <methods>;
}

Testing the sample app

Use adb to launch deep links (in the terminal type: adb shell).

This fires a standard deep link. Source annotation @DeepLink("dld://example.com/deepLink")

am start -W -a android.intent.action.VIEW -d "dld://example.com/deepLink" com.airbnb.deeplinkdispatch.sample

This fires a deep link associated with a method, and also passes along a path parameter. Source annotation @DeepLink("dld://methodDeepLink/{param1}")

am start -W -a android.intent.action.VIEW -d "dld://methodDeepLink/abc123" com.airbnb.deeplinkdispatch.sample

You can include multiple path parameters (also you don't have to include the sample app's package name). Source annotation @DeepLink("http://example.com/deepLink/{id}/{name}")

am start -W -a android.intent.action.VIEW -d "http://example.com/deepLink/123abc/myname"

Note it is possible to call directly adb shell am ... however this seems to miss the URI sometimes so better to call from within shell.

License

Copyright 2015-2020 Airbnb, Inc.

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.
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