判断AccessibilityService是否已经启用

Note : Change value of final String service = "com.test.package.name/com.test.package.name.YOURAccessibilityService" with your Service. 

// To check if service is enabled
private boolean isAccessibilitySettingsOn(Context mContext) {
        int accessibilityEnabled = 0;
        final String service = "com.test.package.name/com.test.package.name.YOURAccessibilityService";
        boolean accessibilityFound = false;
        try {
            accessibilityEnabled = Settings.Secure.getInt(
                    mContext.getApplicationContext().getContentResolver(),
                    android.provider.Settings.Secure.ACCESSIBILITY_ENABLED);
            Log.v(TAG, "accessibilityEnabled = " + accessibilityEnabled);
        } catch (SettingNotFoundException e) {
            Log.e(TAG, "Error finding setting, default accessibility to not found: "
                            + e.getMessage());
        }
        TextUtils.SimpleStringSplitter mStringColonSplitter = new TextUtils.SimpleStringSplitter(':');

        if (accessibilityEnabled == 1) {
            Log.v(TAG, "***ACCESSIBILIY IS ENABLED*** -----------------");
            String settingValue = Settings.Secure.getString(
                    mContext.getApplicationContext().getContentResolver(),
                    Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES);
            if (settingValue != null) {
                TextUtils.SimpleStringSplitter splitter = mStringColonSplitter;
                splitter.setString(settingValue);
                while (splitter.hasNext()) {
                    String accessabilityService = splitter.next();

                    Log.v(TAG, "-------------- > accessabilityService :: " + accessabilityService);
                    if (accessabilityService.equalsIgnoreCase(service)) {
                        Log.v(TAG, "We've found the correct setting - accessibility is switched on!");
                        return true;
                    }
                }
            }
        } else {
            Log.v(TAG, "***ACCESSIBILIY IS DISABLED***");
        }

        return accessibilityFound;      
    }

And call this method as

if (! isAccessibilitySettingsOn(getApplicationContext())) {
            startActivity(new Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS));
        }

This will check and launch accessibility settings if not enabled.

http://stackoverflow.com/questions/18094982/detect-if-my-accessibility-service-is-enabled