实战Android：用AccessibilityService捕获volume按键

╰+哭是因爲堅強的太久メ 2022-05-18 03:13 428阅读 0赞

要在后台捕获并处理按键，AccessibilityService是个好办法。当然其局限性也很明显，其一，AccessibilityService和其他Service最大的一个区别就是，必须在Setting->Accessibity Setting中获得用户的许可。而且，一旦启动，他的管理就在于操作系统，你无法在中途将其退出（不用的时候占着资源，挺烦的）。其二，对于用户而言，在后台弄这么一个有某方面监控大权的app，也不是一个很好的体验。

言归正传，下面我们来看源码说明。

**1。Notification**

我这里为了让用户明确看到程序在后台，特地挂了个Notification, （accessIntent.setAction("com.android.vending");这句是为了避免explicit报错）。

accessIntent = new Intent(MainActivity.this, KeyAccessibilityService.class);
    accessIntent.setAction(Settings.ACTION_ACCESSIBILITY_SETTINGS);
    accessIntent.setAction("com.android.vending");

如果你不想要那个Notification显示在手机前台，可以这么写

accessIntent = new Intent();
    accessIntent.setAction(Settings.ACTION_ACCESSIBILITY_SETTINGS);
    accessIntent.setAction("com.android.vending");

**2。避免不需要响应时拦截按键信息**

由于是常驻内存，所以为了避免不需要响应时拦截按键信息，定义  
public static boolean isAccessAlive = false;  
当需要拦截时，把isAccessAlive设置成true，当不需要拦截时，设置成false就不影响系统的音量调节了（我这里以音量键为例写的）。

**3。使用时需要设置AccessibityService**

我用的华为手机，安装完后，其设置是在  
设置-》高级设置-》辅助功能-》keyActionService  
这个keyActionService就是我们的监听程序。其他手机可能不一样，Android模拟机中是setting->accessibility。

这个显示的界面，其xml文件就是res->xml->accessibility\_service\_config.xml。

![70][]

运行时debug显示捕捉到的按键信息如下，

![70 1][]

## 源码 ##

如下，

布局activity\_main.java

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout 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:orientation="vertical"
        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=".MainActivity">
    
        <Button
            android:id="@+id/btn_white"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/service_white" />
    
        <Button
            android:id="@+id/btn_stop_white"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/stop_white" />  
    
        <Button
            android:id="@+id/btn_exit"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/exit" />
    </LinearLayout>

MainActivity.java

package com.spacesoftwares.spacecapture;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    import android.provider.Settings;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    
    import com.spacesoftwares.spacecapture.service.KeyAccessibilityService;
    
    public class MainActivity extends AppCompatActivity {
    
        private Button mBtnWhite, mBtnStopWhite, mBtnExit; // mBtnBlack, mBtnStopBack,
    
        private final static String TAG = MainActivity.class.getSimpleName();
        private Intent accessIntent;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            mBtnWhite = findViewById(R.id.btn_white);
            mBtnStopWhite = findViewById(R.id.btn_stop_white);
            mBtnExit = findViewById(R.id.btn_exit);
            setListener();
        }
    
        @Override
        protected void onDestroy() {
            KeyAccessibilityService.isAccessAlive = false;
            super.onDestroy();
        }
    
        class ExitReceiver extends BroadcastReceiver {
            @Override
            public void onReceive(Context context, Intent intent) {
                MainActivity.this.finish();
            }
        }
    
        private void setListener(){
            OnClick onClick = new OnClick();
            mBtnWhite.setOnClickListener(onClick);
            mBtnStopWhite.setOnClickListener(onClick);
            mBtnExit.setOnClickListener(onClick);
        }
    
        private class  OnClick implements  View.OnClickListener{
            @Override
            public void onClick(View view) {
                int viewId = view.getId();
                switch(viewId){
                    case R.id.btn_white:
                        Log.i(TAG, "MAIN: btn_white");
                        if(null == accessIntent) {
                            // ---- method No. 1 ----
                            //accessIntent = new Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS);
                            //accessIntent.setPackage("com.android.vending");
    
                            // ---- method No. 2 ---- cannot get the key
                            accessIntent = new Intent(MainActivity.this, KeyAccessibilityService.class);
                            accessIntent.setAction(Settings.ACTION_ACCESSIBILITY_SETTINGS);
                            accessIntent.setAction("com.android.vending");
                        }
                        startService(accessIntent);
                        KeyAccessibilityService.isAccessAlive = true;
                        break;
                    case R.id.btn_stop_white:
                        Log.i(TAG, "MAIN: btn_stop_white");
                        if(null != accessIntent)
                            stopService(accessIntent);
                        KeyAccessibilityService.isAccessAlive = false;
                    break;
    
                    case R.id.btn_exit:
                        Log.i(TAG, "MAIN: btn_exit");
                        if(null != accessIntent)
                            stopService(accessIntent);
                        finish();
                        KeyAccessibilityService.isAccessAlive = false;
                        System.exit(0);
                        break;
                }
            }
        }
    
        /*@Override
        public boolean onKeyDown(int keyCode, KeyEvent event) {
            switch(keyCode){
                case KeyEvent.KEYCODE_VOLUME_UP:
                    isVolumeUpKeyPressed = true;
                    System.out.println("keycode_volume_up");
                    Log.i(TAG,"keycode_volume_up");
                    return true;
    
                case KeyEvent.KEYCODE_POWER:
                    System.out.println("keycode_power");
                    Log.i(TAG,"keycode_power");
                    return true;
    
                default:
                    return super.onKeyDown(keyCode, event);
            }
        }
    
        @Override
        public boolean onKeyLongPress(int keyCode, KeyEvent event) {
            return super.onKeyLongPress(keyCode, event);
        }*/
    }

KeyAccessbilityService.java

package com.spacesoftwares.spacecapture.service;
    
    import android.accessibilityservice.AccessibilityService;
    import android.app.Notification;
    import android.app.NotificationChannel;
    import android.app.NotificationManager;
    import android.app.PendingIntent;
    import android.content.Context;
    import android.content.Intent;
    import android.graphics.Color;
    import android.os.Build;
    import android.support.v4.app.NotificationCompat;
    import android.util.Log;
    import android.view.KeyEvent;
    import android.view.accessibility.AccessibilityEvent;
    
    import com.spacesoftwares.spacecapture.MainActivity;
    import com.spacesoftwares.spacecapture.R;
    
    import java.util.Calendar;
    
    public class KeyAccessibilityService extends AccessibilityService {
    
        public static boolean isAccessAlive = false;
    
        private final static int FOREGROUND_ID = 1000;
        private Notification mNotification;
        private static final String TAG_KEY = "KEY_ACCESS";
    
        @Override
        protected boolean onKeyEvent(KeyEvent event) {
            System.out.println("onKeyEvent");
            Log.i(TAG_KEY, "onKeyEvent");
    
            if(isAccessAlive) {
                int key = event.getKeyCode();
    
                switch (key) {
                    case KeyEvent.KEYCODE_VOLUME_DOWN:
                        System.out.println("KEYCODE_VOLUME_DOWN");
                        Log.i(TAG_KEY, "KEYCODE_VOLUME_DOWN");
                        return true;
                    case KeyEvent.KEYCODE_VOLUME_UP:
                        System.out.println("KEYCODE_VOLUME_UP");
                        Log.i(TAG_KEY, "KEYCODE_VOLUME_UP");
                        return true;
                    default:
                        break;
                }
            }
            return super.onKeyEvent(event);
        }
    
    
    
        @Override
        public int onStartCommand(Intent intent, int flags, int startId) {
            if(null != mNotification){
                Log.i(TAG_KEY, "KeyService->onStartCommand->Notification exists");
                return super.onStartCommand(intent, flags, startId);
            }
    
            Log.i(TAG_KEY, "KeyService->onStartCommand->Create Notification");
            //NotificationManager manager = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
            //NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
            String NOTIFICATION_CHANNEL_ID = "my_channel_id_01";
    
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "My Notifications", NotificationManager.IMPORTANCE_HIGH);
    
                // Configure the notification channel.
                notificationChannel.setDescription("Channel description");
                notificationChannel.enableLights(true);
                notificationChannel.setLightColor(Color.RED);
                notificationChannel.setVibrationPattern(new long[]{0, 1000, 500, 1000});
                notificationChannel.enableVibration(true);
    
                NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
                notificationManager.createNotificationChannel(notificationChannel);
            }
    
            NotificationCompat.Builder builder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
            builder.setSmallIcon(R.mipmap.ic_launcher);
            builder.setContentTitle("Foreground");
            builder.setContentText("Text shown on notification bar");
            builder.setContentInfo("Content Info");
            builder.setWhen(System.currentTimeMillis());
    
            Intent activityIntent = new Intent(this, MainActivity.class);
            PendingIntent pendingIntent = PendingIntent.getActivity(this, 1, activityIntent, PendingIntent.FLAG_UPDATE_CURRENT);
            builder.setContentIntent(pendingIntent);
            mNotification = builder.build();
            startForeground(FOREGROUND_ID, mNotification);
            return super.onStartCommand(intent, flags, startId);
        }
    
        @Override
        protected void onServiceConnected() {
            System.out.println("KEYCODE_onServiceConnected");
            Log.i(TAG_KEY, "KEYCODE_onServiceConnected");
            super.onServiceConnected();
        }
    
        @Override
        public void onAccessibilityEvent(AccessibilityEvent accessibilityEvent) {
            System.out.println("KEYCODE_onAccessibilityEvent");
            Log.i(TAG_KEY, "KEYCODE_onAccessibilityEvent");
        }
    
        @Override
        public void onInterrupt() {
        }
    }

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="com.spacesoftwares.spacecapture">
        <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:theme="@style/AppTheme">
            <activity
                android:name=".MainActivity"
                android:launchMode="singleTask">
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
    
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
    
            <service
                android:name=".service.KeyAccessibilityService"
                android:enabled="true"
                android:exported="true"
                android:label="@string/keyActionService"
                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/accessibility_service_config" />
            </service>
        </application>
    
    </manifest>

res->xml->accessibility\_service\_config.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="flagRequestFilterKeyEvents"
        android:canRetrieveWindowContent="true"
        android:canRequestFilterKeyEvents="true"
        android:description="@string/accessibility_description"
        android:notificationTimeout="1000"/>

完整的项目资源在这里下载，

[https://download.csdn.net/download/tanmx219/10570716][https_download.csdn.net_download_tanmx219_10570716]

[70]: /images/20220518/f0ee10adde854592b36eaadd599e9164.png
[70 1]: /images/20220518/f62c5e408e634da8b3a04a5ef47f2b39.png
[https_download.csdn.net_download_tanmx219_10570716]: https://download.csdn.net/download/tanmx219/10570716