背景

标准Android系统提供AccessibilityService以满足残障人群使用App的需求，同时提供talkback服务以语音播报的方式提供服务，开发者也可能通过继承实现AccessibilityService实现自己的无障碍支持。目前市面上已经存在一些无障碍支持软件如保益悦听、点明安卓、解说等，这类软件同样是基于语音播报的方式提供服务。

此外，还有些软件如爱奇异App也使用了AccessibilityService，然而此类App不是为了提供无障碍服务，而是使用AccessibilityService以实现诸如自动安装等功能，所以在进行无障碍服务是否开启的判断中要排除此类App使用AccessibilityService的方式。

所以如何准确判断用户是否开启无障碍服务需要考虑以上所有场景。

代码实现

综上所述，具体实现代码如下：

public static boolean isAccessibilityEnabled(Context context) throws RuntimeException{
        if (context == null) {
            return false;
        }

        // 检查AccessibilityService是否开启
        AccessibilityManager am = (AccessibilityManager) context.getSystemService(android.content.Context.ACCESSIBILITY_SERVICE);
        boolean isAccessibilityEnabled_flag = am.isEnabled();
    
        boolean isExploreByTouchEnabled_flag = false;

        // 检查无障碍服务是否以语音播报的方式开启
        isExploreByTouchEnabled_flag = isScreenReaderActive(context);

        return (isAccessibilityEnabled_flag && isExploreByTouchEnabled_flag);

    }
    private final static String SCREEN_READER_INTENT_ACTION = "android.accessibilityservice.AccessibilityService";
    private final static String SCREEN_READER_INTENT_CATEGORY = "android.accessibilityservice.category.FEEDBACK_SPOKEN";

    private static boolean isScreenReaderActive(Context context) {

        // 通过Intent方式判断是否存在以语音播报方式提供服务的Service，还需要判断开启状态
        Intent screenReaderIntent = new Intent(SCREEN_READER_INTENT_ACTION);
        screenReaderIntent.addCategory(SCREEN_READER_INTENT_CATEGORY);
        List<ResolveInfo> screenReaders = context.getPackageManager().queryIntentServices(screenReaderIntent, 0);
        // 如果没有，返回false
        if (screenReaders == null || screenReaders.size() <= 0) {
            return false;
        }

        boolean hasActiveScreenReader = false;
        if (Build.VERSION.SDK_INT <= 15) {
            ContentResolver cr = context.getContentResolver();
            Cursor cursor = null;
            int status = 0;

            for (ResolveInfo screenReader : screenReaders) {
                cursor = cr.query(Uri.parse("content://" + screenReader.serviceInfo.packageName
                        + ".providers.StatusProvider"), null, null, null, null);

                if (cursor != null && cursor.moveToFirst()) { 
                    status = cursor.getInt(0);
                    cursor.close();
                    // 状态1为开启状态，直接返回true即可
                    if (status == 1) {
                        return true;
                    }
                }
            }
        } else if (Build.VERSION.SDK_INT >= 26) {
            // 高版本可以直接判断服务是否处于开启状态
            for (ResolveInfo screenReader : screenReaders) {
                hasActiveScreenReader |= isAccessibilitySettingsOn(context, screenReader.serviceInfo.packageName + "/" + screenReader.serviceInfo.name);
            }

        } else {
            // 判断正在运行的Service里有没有上述存在的Service
            List<String> runningServices = new ArrayList<String>();

            android.app.ActivityManager manager = (android.app.ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
            for (android.app.ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
                runningServices.add(service.service.getPackageName());
            }

            for (ResolveInfo screenReader : screenReaders) {
                if (runningServices.contains(screenReader.serviceInfo.packageName)) {
                    hasActiveScreenReader |= true;
                }
            }
        }

        return hasActiveScreenReader;
    }

    // To check if service is enabled
    private static boolean isAccessibilitySettingsOn(Context context, String service) {

        TextUtils.SimpleStringSplitter mStringColonSplitter = new TextUtils.SimpleStringSplitter(':');
        String settingValue = Settings.Secure.getString(
                context.getApplicationContext().getContentResolver(),
                Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES);
        if (settingValue != null) {
            mStringColonSplitter.setString(settingValue);
            while (mStringColonSplitter.hasNext()) {
                String accessibilityService = mStringColonSplitter.next();
                if (accessibilityService.equalsIgnoreCase(service)) {
                    return true;
                }
            }
        }

        return false;
    }