I’ve created a sample code for building autofill services. This guide walks you through the implementation and provides an overview of the necessary changes.
For setup instructions, please refer to this document: Chrome on Android to support third-party autofill services natively.
The implementation presented here simply shows autofill suggestions for the username text field.
Below are the modifications and newly created files from this project in Android Studio:
app
|---manifests
| |---- AndroidManifest.xml
|
|---kotlin+java
| |---- com.example.myautofillapplication
| |----- MyAutofillService.kt
|
|------res
| |---- values
| | |---- string.xml
| |
| |---- xml
| | |---- autofill_service_config.xml
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" >
<application
android:allowBackup="true"
android:dataExtractionRules="@xml/data_extraction_rules"
android:fullBackupContent="@xml/backup_rules"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.MyAutofillApplication"
tools:targetApi="31" >
<activity
android:name=".MainActivity"
android:exported="true"
android:label="@string/app_name"
android:theme="@style/Theme.MyAutofillApplication" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- Added autofill service element -->
<service
android:name=".MyAutofillService"
android:exported="true"
android:label="My Autofill Service"
android:permission="android.permission.BIND_AUTOFILL_SERVICE">
<intent-filter>
<action android:name="android.service.autofill.AutofillService" />
</intent-filter>
<meta-data
android:name="android.autofill"
android:resource="@xml/autofill_service_config" />
</service>
</application>
</manifest>
MyAutofillService.kt
The core of the autofill functionality is implemented in MyAutofillService.kt. This new file provides the logic for processing autofill requests and suggesting autofill data.
package com.example.myautofillapplication
import android.app.assist.AssistStructure
import android.os.CancellationSignal
import android.service.autofill.*
import android.util.Log
import android.view.autofill.AutofillId
import android.view.autofill.AutofillValue
import android.widget.RemoteViews
class MyAutofillService : AutofillService() {
override fun onFillRequest(
request: FillRequest,
cancellationSignal: CancellationSignal,
callback: FillCallback
) {
Log.d(TAG, "onFillRequest called")
val structure = request.fillContexts.last().structure
Log.d(TAG, "AssistStructure: windowNodeCount = ${structure.windowNodeCount}")
val targetFields = extractAutofillIds(structure)
if (targetFields.isEmpty()) {
Log.d(TAG, "No username fields found")
callback.onFailure("No fields to autofill")
return
}
callback.onSuccess(
FillResponse.Builder()
.addDataset(buildDataset(targetFields, "example_user"))
.build()
)
}
private fun extractAutofillIds(structure: AssistStructure): List<AutofillId> {
return (0 until structure.windowNodeCount).flatMap { index ->
val windowNode = structure.getWindowNodeAt(index)
Log.d(TAG, "Traversing windowNode $index: title = ${windowNode.title}")
findUsernameFields(windowNode.rootViewNode)
}
}
private fun findUsernameFields(node: AssistStructure.ViewNode): List<AutofillId> {
val matches = mutableListOf<AutofillId>()
node.htmlInfo?.attributes?.forEach { attribute ->
val key = attribute.first
val value = attribute.second
if (key == "name" && value == "username") {
Log.d(TAG, "Match found: idEntry=${node.idEntry}, hint=${node.hint}")
node.autofillId?.let { matches.add(it) }
}
}
repeat(node.childCount) { index ->
Log.d(TAG, "Traversing child $index of node: idEntry=${node.idEntry}")
matches += findUsernameFields(node.getChildAt(index))
}
return matches
}
private fun buildDataset(fields: List<AutofillId>, username: String): Dataset {
val presentation = RemoteViews(packageName, android.R.layout.simple_list_item_1).apply {
setTextViewText(android.R.id.text1, "Autofill Username")
}
return Dataset.Builder().apply {
fields.forEach { autofillId ->
setValue(
autofillId,
AutofillValue.forText(username),
presentation
)
}
}.build()
}
override fun onSaveRequest(request: SaveRequest, callback: SaveCallback) {
// Saving user input data if required
}
companion object {
private const val TAG = "MyAutofillService"
}
}
string.xml
Updated string.xml to include a description for the autofill service.
<resources>
<string name="app_name">MyAutofillApplication</string>
<!-- Added service description -->
<string name="service_description">MyAutofillApplicationTestApplication</string>
</resources>
autofill_service_config.xml
Added a new configuration file for the autofill service.
<?xml version="1.0" encoding="utf-8"?>
<autofill-service
xmlns:android="http://schemas.android.com/apk/res/android"
android:settingsActivity="com.example.myautofillapplication.SettingsActivity"
android:description="@string/service_description" />
