android.accessibilityservice.AccessibilityService.getSystemService(AccessibilityService.java:1602)：java.lang.IllegalStateException

Question

我在我的应用程序中使用了可访问性服务来向用户读出自定义文本。这是我的服务类：

class GlobalAccessibilityService: AccessibilityService() {
    override fun onInterrupt() {
        Log.i("Accessibility","onInterrupt()")
    }

    override fun onAccessibilityEvent(event: AccessibilityEvent?) {
        Log.i("Accessibility","onAccessibilityEvent() & Even is: "+event.toString())
    }
}

我已经在Manifest的Service tag下声明了它，并有相应的xml文件。

下面是我在Activity类中调用服务的方式：

     var mService = GlobalAccessibilityService()

       var manager: AccessibilityManager = mService.getSystemService(Context.ACCESSIBILITY_SERVICE) 

                    if (manager.isEnabled){
                        var event: AccessibilityEvent = AccessibilityEvent.obtain()
                        event.eventType = AccessibilityEvent.TYPE_ANNOUNCEMENT
                        event.text.add("This is a test for Accessibility Service Announcement")
                        manager.sendAccessibilityEvent(event)
                    }

但是，我得到了以下错误：

     java.lang.IllegalStateException: System services not available to Activities before onCreate()
            at android.accessibilityservice.AccessibilityService.getSystemService(AccessibilityService.java:1602)

请求帮助！谢谢。

Answer 1

看起来你在调用下面写的在onCreate()之前的方法。您将在何处调用以下代码？：

var mService = GlobalAccessibilityService()

   var manager: AccessibilityManager = mService.getSystemService(Context.ACCESSIBILITY_SERVICE) 

                if (manager.isEnabled){
                    var event: AccessibilityEvent = AccessibilityEvent.obtain()
                    event.eventType = AccessibilityEvent.TYPE_ANNOUNCEMENT
                    event.text.add("This is a test for Accessibility Service Announcement")
                    manager.sendAccessibilityEvent(event)
                }

Answer 2

变量mService = GlobalAccessibilityService()

你不能实例化一个Service并期望它能工作。Android框架为您实例化服务。

对于正常的服务，可以使用带有startService()调用的Intent，但是AccessibilityService是不同的。请参阅How to start AccessibilityService?