Step‑by‑Step Guide to Android AccessibilityService for UI Automation

This tutorial begins with a brief introduction to Android automation, emphasizing that all Android automation frameworks rely on adb and the AccessibilityService.

It then explains why using AccessibilityService allows you to package automation scripts into an APK, making distribution easier compared to PC‑based adb scripts.

0x1. Introduction

The author greets readers and repeats the core premise: all Android automation functions are built on adb and AccessibilityService.

0x2. AccessibilityService Overview

Official Android documentation describes AccessibilityService as a service that provides UI enhancements for users with disabilities, and developers can create their own services.

It can assist users who cannot fully interact with the device, such as when driving or in noisy environments.

The service essentially enables an app to control other apps (click, scroll, input, etc.).

0x3. Basic Usage of AccessibilityService

AccessibilityService is a subclass of Service . When the user enables the service, the system calls onServiceConnected() ; when the service is disabled or the process is killed, disableSelf() is invoked.

① Create a custom AccessibilityService

Extend AccessibilityService and override onInterrupt() and onAccessibilityEvent() :

import android.accessibilityservice.AccessibilityService
import android.util.Log
import android.view.accessibility.AccessibilityEvent

class JumpAdAccessibilityService : AccessibilityService() {
    val TAG = javaClass.simpleName
    override fun onAccessibilityEvent(event: AccessibilityEvent?) {
        Log.d(TAG, "onAccessibilityEvent：$event")
    }
    override fun onInterrupt() {
        Log.d(TAG, "onInterrupt")
    }
}

The two overridden methods are mandatory.

onInterrupt() – called when the service is interrupted.

onAccessibilityEvent() – called for each received AccessibilityEvent (e.g., notifications, UI changes).

② Register the Service

Add a <service> entry in AndroidManifest.xml :

<service
    android:name=".JumpAdAccessibilityService"
    android:exported="false"
    android:label="跳过广告哈哈哈哈"
    android:permission="android.permission.BIND_ACCESSIBILITY_SERVICE">
    <intent-filter>
        <action android:name="android.accessibilityservice.AccessibilityService" />
    </intent-filter>
</service>

Tip: the permission ensures only the system can bind the service; the label is shown in the accessibility settings UI.

③ Configure Event Listening

You can configure the service either dynamically in code (via onServiceConnected() ) or statically with an XML meta‑data file.

Dynamic configuration

override fun onServiceConnected() {
    val serviceInfo = AccessibilityServiceInfo().apply {
        eventTypes = AccessibilityEvent.TYPES_ALL_MASK
        feedbackType = AccessibilityServiceInfo.FEEDBACK_GENERIC
        flags = AccessibilityServiceInfo.DEFAULT
        packageNames = arrayOf("com.tencent.mm") // monitor WeChat
        notificationTimeout = 10
    }
    setServiceInfo(serviceInfo)
}

Static configuration

Create res/xml/accessible_service_config_jump_ad.xml :

<?xml version="1.0" encoding="utf-8"?>
<accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"
    android:accessibilityEventTypes="typeAllMask"
    android:accessibilityFeedbackType="feedbackGeneric"
    android:accessibilityFlags="flagDefault"
    android:canRetrieveWindowContent="true"
    android:description="@string/accessibility_desc"
    android:notificationTimeout="100"
    android:packageNames="com.tencent.mm"
    android:settingsActivity="cn.coderpig.jumpad.MainActivity" />

Static configuration offers more options, while dynamic configuration is more flexible.

④ Enable the Service

After installing the app, enable the service via Settings → Accessibility → your app. The system will prompt for permission.

0x4. Common Tricks

Check whether the service is enabled.

Find nodes using AccessibilityEvent.getSource() or AccessibilityService.getRootInActiveWindow() .

Search nodes by text ( findAccessibilityNodeInfosByText() ) or view ID ( findAccessibilityNodeInfosByViewId() ).

Interact with nodes using performAction() (click, long‑click, scroll, input).

Execute global actions with performGlobalAction() (back, home, etc.).

① Check Service Status

fun Context.isAccessibilitySettingsOn(clazz: Class
): Boolean {
    var enabled = false
    try {
        enabled = Settings.Secure.getInt(contentResolver, Settings.Secure.ACCESSIBILITY_ENABLED) == 1
    } catch (e: Settings.SettingNotFoundException) { e.printStackTrace() }
    if (enabled) {
        val setting = Settings.Secure.getString(contentResolver, Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES)
        setting?.let {
            val splitter = SimpleStringSplitter(':')
            splitter.setString(it)
            while (splitter.hasNext()) {
                if (splitter.next().equals("${packageName}/${clazz.canonicalName}", true)) return true
            }
        }
    }
    return false
}

Call this method in onResume() to guide the user to the accessibility settings page if needed:

startActivity(Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS))

② Node Searching

Use AccessibilityEvent.getSource() or getRootInActiveWindow() to obtain the current AccessibilityNodeInfo , then search by text or view ID.

③ Node Interaction

// Click
fun AccessibilityNodeInfo.click() = performAction(AccessibilityNodeInfo.ACTION_CLICK)
// Long click
fun AccessibilityNodeInfo.longClick() = performAction(AccessibilityNodeInfo.ACTION_LONG_CLICK)
// Scroll forward
fun AccessibilityNodeInfo.scrollForward() = performAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD)
// Input text
fun AccessibilityNodeInfo.input(content: String) = performAction(
    AccessibilityNodeInfo.ACTION_SET_TEXT,
    Bundle().apply { putCharSequence(AccessibilityNodeInfo.ACTION_ARGUMENT_SET_TEXT_CHARSEQUENCE, content) }
)

④ Global Interaction

performGlobalAction(GLOBAL_ACTION_BACK)   // Back button
performGlobalAction(GLOBAL_ACTION_HOME)   // Home button

0x5. Simple Case: Automatic WeChat Login on Windows/Mac

The author builds a minimal app that monitors WeChat login windows (event type TYPE_WINDOW_STATE_CHANGED with class ExtDeviceWXLoginUI ) and automatically clicks the login button using the node‑search and click utilities described above.

Key steps:

Detect whether the AccessibilityService is enabled.

Configure the service to listen to all events for the WeChat package.

In onAccessibilityEvent() , filter for TYPE_WINDOW_STATE_CHANGED and the target class name.

Locate the login button either by text containing "登录" or by its unique view ID, then invoke click() .

The result is an instant automatic login without user interaction.

0x6. Conclusion

The article covered the basics of AccessibilityService, common tricks, and a concrete example. Future topics will include a WeChat zombie‑friend detection tool.

References

Official documentation: "Create your own AccessibilityService".

AccessibilityService introductory guides.

Various community notes on AccessibilityService.