Set up app links for Android
Deep linking is a mechanism for launching an app with a URI. This URI contains scheme, host, and path, and opens the app to a specific screen.
A app link is a type of deep link that uses http
or https
and
is exclusive to Android devices.
Setting up app links requires one to own a web domain. Otherwise, consider using Firebase Hosting or GitHub Pages as a temporary solution.
1. Customize a Flutter application
Write a Flutter app that can handle an incoming URL.
This example uses the go_router package to handle the routing.
The Flutter team maintains the go_router
package.
It provides a simple API to handle complex routing scenarios.
-
To create a new application, type
flutter create <app-name>
.$ flutter create deeplink_cookbook
-
To include
go_router
package in your app, add a dependency forgo_router
in thepubspec.yaml
file.dependencies: flutter: sdk: flutter go_router: ^6.0.9
-
To handle the routing, create a
GoRouter
object in themain.dart
file:import 'package:flutter/material.dart'; import 'package:go_router/go_router.dart'; void main() => runApp(MaterialApp.router(routerConfig: router)); /// This handles '/' and '/details'. final router = GoRouter( routes: [ GoRoute( path: '/', builder: (_, __) => Scaffold( appBar: AppBar(title: const Text('Home Screen')), ), routes: [ GoRoute( path: 'details', builder: (_, __) => Scaffold( appBar: AppBar(title: const Text('Details Screen')), ), ), ], ), ], );
2. Modify AndroidManifest.xml
- Open the Flutter project with Android Studio or VSCode.
- Navigate to
android/app/src/main/AndroidManifest.xml
file -
Add the following metadata tag and intent filter inside the
<activity>
tag with.MainActivity
Replace
example.com
with your own web domain.<meta-data android:name="flutter_deeplinking_enabled" android:value="true" /> <intent-filter android:autoVerify="true"> <action android:name="android.intent.action.VIEW" /> <category android:name="android.intent.category.DEFAULT" /> <category android:name="android.intent.category.BROWSABLE" /> <data android:scheme="http" android:host="example.com" /> <data android:scheme="https" /> </intent-filter>
3. Hosting assetlinks.json file
Host an assetlinks.json
file in using a web server with a domain that you own.
This file tells the mobile browser which Android application to open instead of the browser.
To create the file, get the package name of the Flutter app you created in the previous step and
the sha256 fingerprint of the signing key you will be using to build the APK.
Package name
Locate the package name in AndroidManifest.xml
, the package
property under <manifest>
tag.
Package names are usually in the format of com.example.*
.
sha256 fingerprint
Process may differ depending on the way apk is signed.
Using google play app signing
You can find the sha256 fingerprint directly from play developer console. Open your app in the play
console, under Release> Setup > App Integrity> App Signing tab
Using local keystore
If you are storing the key locally, you can generate sha256 using the following command.
keytool -list -v -keystore <path-to-keystore>
assetlinks.json
The hosted file should look similar to this:
[{
"relation": ["delegate_permission/common.handle_all_urls"],
"target": {
"namespace": "android_app",
"package_name": "com.example.deeplink_cookbook",
"sha256_cert_fingerprints":
["FF:2A:CF:7B:DD:CC:F1:03:3E:E8:B2:27:7C:A2:E3:3C:DE:13:DB:AC:8E:EB:3A:B9:72:A1:0E:26:8A:F5:EC:AF"]
}
}]
-
Set the
package_name
value to your Android application ID. -
Set sha256_cert_fingerprints to the value you got from the previous step.
-
Host the file at a URL that resembles the following:
<webdomain>/.well-known/assetlinks.json
-
Verify that your browser can access this file.
Testing
You can use a real device or the Emulator to test a app link,
but first make sure you have executed flutter run
at least once on
the devices. This ensures that the Flutter application is installed.
To test only the app setup, use the adb command:
adb shell 'am start -a android.intent.action.VIEW \
-c android.intent.category.BROWSABLE \
-d "http://<web-domain>/details"' \
<package name>
To test both web and app setup, you need to click on a link directly through web browser or other apps. One way is to create a Google Doc, add the link, and tap on it.
If everything is set up correctly, the Flutter application launches and displays the details screen:
Appendix
Source code: deeplink_cookbook