android - Activity 开始时，服务无法捕获可访问性事件

我正在尝试让我的应用在用户启动Activity时向我的自定义AccessibilityService宣布一些信息。我有一个TextView，它在活动开始时会调用requestFocus（），然后发送AccessibilityEvent，以使AccessibilityService读取TextView的内容描述。我已将问题隔离到一个小型应用程序中。

这是主要活动：

package com.example.ttstest;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.accessibility.AccessibilityEvent;

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        View v = findViewById(R.id.textView1);
        v.requestFocus();
        v.sendAccessibilityEvent(AccessibilityEvent.TYPE_ANNOUNCEMENT);
    }
}

布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.ttstest.MainActivity" >

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:focusable="true"
        android:focusableInTouchMode="true"
        android:contentDescription="Secondarily focused text view"
        android:text="@string/hello_world" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView2"
        android:layout_marginLeft="54dp"
        android:layout_marginTop="145dp"
        android:layout_toRightOf="@+id/textView2"
        android:contentDescription="Initially focused text view"
        android:focusable="true"
        android:focusableInTouchMode="true"
        android:text="Initially focused text view" />

</RelativeLayout>

和AccessibilityService：

package com.example.ttstest;

import android.accessibilityservice.AccessibilityService;
import android.speech.tts.TextToSpeech;
import android.speech.tts.TextToSpeech.OnInitListener;
import android.util.Log;
import android.view.accessibility.AccessibilityEvent;

public class TextToSpeechService extends AccessibilityService {
    private static TextToSpeech textToSpeech = null;
    private static boolean ttsReady = false;

    @Override
    protected void onServiceConnected() {
        super.onServiceConnected();
        Log.e("TextToSpeechService", "Got to onServiceConnected()");
        textToSpeech = new TextToSpeech(this.getApplicationContext(), new OnInitListener() {
            @Override
            public void onInit(int status) {
                if(status == TextToSpeech.SUCCESS) {
                    ttsReady = true;
                }
            }
        });
    }

    @Override
    public void onAccessibilityEvent(AccessibilityEvent event) {
        Log.e("TextToSpeechService", "Entering onAccessibilityEvent().");
        Log.e("TextToSpeechService", "Event type: " + event.getEventType() + ", from class " + event.getClassName());
        if(event.getContentDescription() != null) {
            Log.e("TextToSpeechService", "" + event.getContentDescription());
        }
        if(textToSpeech != null && ttsReady == true) {
            if(event.getEventType() == AccessibilityEvent.TYPE_VIEW_FOCUSED) {
                CharSequence contentDescription = event.getContentDescription();
                if(contentDescription != null) {
                    String say = contentDescription.toString();
                    textToSpeech.speak(say, TextToSpeech.QUEUE_FLUSH, null);
                }
            } else if (event.getEventType() == AccessibilityEvent.TYPE_ANNOUNCEMENT) {
                CharSequence contentDescription = event.getContentDescription();
                if(contentDescription != null) {
                    textToSpeech.speak(event.getContentDescription().toString(), TextToSpeech.QUEUE_FLUSH, null);
                }
            }
        }
        Log.e("TextToSpeechService", "Exiting onAccessibilityEvent().");
    }

    @Override
    public void onInterrupt() {
        Log.e("TextToSpeechService", "Entering onInterrupt()");
        if(textToSpeech != null && ttsReady == true) {
            textToSpeech.stop();
        }
    }
}

这已添加到我的AndroidManifest.xml中的适当位置：

<service android:name="com.example.ttstest.TextToSpeechService"
    android:permission="android.permission.BIND_ACCESSIBILITY_SERVICE" >
    <intent-filter>
        <action android:name="android.accessibilityservice.AccessibilityService" />
    </intent-filter>

    <meta-data android:name="android.accessibilityservice"
        android:resource="@xml/accessibilityservice"/>
</service>

我的accessibilityservice.xml设置：

<?xml version="1.0" encoding="utf-8"?>
<accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"
    android:accessibilityEventTypes="typeAllMask"
    android:notificationTimeout="100"
    android:accessibilityFeedbackType="feedbackSpoken"
    android:accessibilityFlags="flagDefault"
    android:canRetrieveWindowContent="true"
    android:packageNames="com.example.ttstest"/>

最后，问题。当我第一次启动应用程序时，TextView不能从requestFocus（）获得焦点，或者对sendAccessibilityEvent（）的调用实际上都不会向AccessibilityService发送任何内容。如果我通过连接物理键盘在TextViews中进行切换，则会收到焦点事件。我已经确保在设置中打开AccessibilityService，并且从我做这个示例的应用程序中得到的证据是，在调用requestFocus（）和sendAccessibilityEvent（）时启用了AccessibilityService。这没有帮助。似乎在首次启动Activity时，这些方法都不向AccessibilityService发送任何内容。我也尝试过以类似结果调用announceForAccessibility（）。

我做错了吗？我该如何解决，或者至少可以解决它？具体来说，我想在活动首次启动时将事件发送到我的AccessibilityService。

更多信息：我尝试将requestFocus（）和sendAccessibilityEvent（）调用移到onStart（）和onWindowFocusChanged（）;上。这些都不起作用。

最佳答案