Android 保持互相呼叫服务/广播
我正在构建一个简单的应用程序,它可以持续监控媒体级别,并一直将其调整为最高级别的20%,如果用户增加,它应该会再次回到20% 我遵循的概念是通过一个服务进行监控,一旦这个服务被破坏,它会调用一个广播接收器,而广播接收器又会再次调用接收器,以此类推,这是一个无休止的循环,但下面的代码看起来有些错误,soit没有按预期工作,服务/广播也不会继续互相调用 我以以下方式启动了Android 保持互相呼叫服务/广播,android,kotlin,Android,Kotlin,我正在构建一个简单的应用程序,它可以持续监控媒体级别,并一直将其调整为最高级别的20%,如果用户增加,它应该会再次回到20% 我遵循的概念是通过一个服务进行监控,一旦这个服务被破坏,它会调用一个广播接收器,而广播接收器又会再次调用接收器,以此类推,这是一个无休止的循环,但下面的代码看起来有些错误,soit没有按预期工作,服务/广播也不会继续互相调用 我以以下方式启动了main活动: class MainActivity : AppCompatActivity() { override
main活动
:
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val audio = this.getSystemService(Context.AUDIO_SERVICE) as AudioManager
val level = audio.getStreamVolume(AudioManager.STREAM_MUSIC)
val maxVolume = audio.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
val percent = 0.2f
val twintyVolume = (maxVolume * percent).toInt()
if ( level > twintyVolume) {
Toast.makeText(this,"audio level is $level", Toast.LENGTH_LONG).show()
audio.setStreamVolume(AudioManager.STREAM_MUSIC,twintyVolume,0)
}
this.startService(Intent(this, VolumeCheck::class.java))
}
}
以上操作将进行初始检查,并将介质卷减少到最大卷的20%,然后启动该服务,该服务使用以下代码执行相同操作:
class VolumeCheck : Service() {
private lateinit var context: Context
override fun onCreate() {
super.onCreate()
context = this
Toast.makeText(this, "service created", Toast.LENGTH_SHORT).show();
}
override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
super.onStartCommand(intent, flags, startId)
Toast.makeText(this, "service starting", Toast.LENGTH_SHORT).show();
val audio = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
val mediaPlayer = MediaPlayer()
// Thread().run {
val maxVolume = audio.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
val percent = 0.2f
val twintyVolume = (maxVolume * percent).toInt()
if (mediaPlayer.isPlaying) {
val level = audio.getStreamVolume(AudioManager.STREAM_MUSIC)
if ( level > twintyVolume) {
Toast.makeText(context,"audio level is $level", Toast.LENGTH_LONG).show()
audio.setStreamVolume(AudioManager.STREAM_MUSIC,twintyVolume,0)
}
}
// Thread.sleep(3000)
// }
stopSelf()
return Service.START_STICKY
}
override fun onBind(intent: Intent): IBinder? {
//TODO for communication return IBinder implementation
return null
}
override fun onDestroy() {
super.onDestroy()
Toast.makeText(this, "service done", Toast.LENGTH_SHORT).show()
val intent = Intent("com.kortex.mediafix.BootUpReceiver")
sendBroadcast(intent)
}
}
一旦服务被破坏,它将调用引导广播接收器,引导广播接收器将再次调用服务:
class BootUpReceiver: BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
context.startService(Intent(context, VolumeCheck::class.java))
}
}
清单是:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.kortex.mediafix">
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<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">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name=".BootUpReceiver"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.QUICKBOOT_POWERON" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
<service android:name=".VolumeCheck" />
</application>
</manifest>
这一行不调用您的广播接收器,而是以“com.kortex.mediafix.bootupureceiver”的形式进行意图与意图操作
更改清单中BootUpReceiver的条目以接收此操作
<receiver android:name=".BootUpReceiver"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.QUICKBOOT_POWERON" />
<action android:name="com.kortex.mediafix.BootUpReceiver" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
我通过使用服务调用的ContentObserver
解决了这个问题,因此我现在的代码是:
MainActivity
启动应用程序、进行首次调整以及启动服务:
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val audio = this.getSystemService(Context.AUDIO_SERVICE) as AudioManager
val level = audio.getStreamVolume(AudioManager.STREAM_MUSIC)
val maxVolume = audio.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
val percent = 0.2f
val twintyVolume = (maxVolume * percent).toInt()
if ( level > twintyVolume) audio.setStreamVolume(AudioManager.STREAM_MUSIC,twintyVolume,0)
Toast.makeText(this,"Audio level adjusted to 20% instead of $level", Toast.LENGTH_LONG).show()
this.startService(Intent(this, VolumeCheck::class.java))
finish()
}
}
广播
每次重新启动设备时启动应用程序和服务:
class BootUpReceiver: BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
context.startService(Intent(context, VolumeCheck::class.java))
}
}
服务
注册并呼叫观察员:
class VolumeCheck : Service() {
private lateinit var context: Context
private lateinit var myObserver: VolumeOnserver
override fun onCreate() {
super.onCreate()
context = this
// Define the VolumeOnserver
myObserver = VolumeOnserver(context, Handler())
Toast.makeText(this, "service created", Toast.LENGTH_SHORT).show();
}
override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
super.onStartCommand(intent, flags, startId)
Toast.makeText(this, "service starting", Toast.LENGTH_SHORT).show();
// Register the VolumeOnserver for setting changes
contentResolver.registerContentObserver(android.provider.Settings.System.CONTENT_URI ,true, myObserver);
return Service.START_STICKY
}
override fun onBind(intent: Intent): IBinder? {
return null
}
override fun onDestroy() {
super.onDestroy()
// Unregister the VolumeOnserver
contentResolver.unregisterContentObserver(myObserver);
}
}
观察者
观察设置的任何变化
并检查媒体音量,必要时进行调整:
class VolumeOnserver (context: Context, h: Handler?): ContentObserver(h) {
private val context = context
override fun onChange(selfChange: Boolean) {
onChange(selfChange, uri = null)
}
// Implement the onChange(boolean, Uri) method to take advantage of the new Uri argument.
override fun onChange(selfChange: Boolean, uri: Uri?) {
// Handle change.
val audio = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
val level = audio.getStreamVolume(AudioManager.STREAM_MUSIC)
val maxVolume = audio.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
val percent = 0.2f
val twintyVolume = (maxVolume * percent).toInt()
if ( level > twintyVolume) audio.setStreamVolume(AudioManager.STREAM_MUSIC,twintyVolume,0)
// Toast.makeText(context,"audio level is $level", Toast.LENGTH_LONG).show()
}
}
清单
文件为:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.kortex.mediafix">
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<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">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name=".BootUpReceiver"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.QUICKBOOT_POWERON" />
<action android:name="com.kortex.mediafix.BootUpReceiver" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
<service android:name=".VolumeCheck" />
</application>
</manifest>
但有一个问题是它不稳定,我认为用户坚持要改变音量,经过多次尝试,服务和/或观察员是/是不再工作,直到应用程序重新启动 另一种不使用服务的方法是从BroadcastReceiver
广播接收机
:
类BootUpReceiver:BroadcastReceiver(){
ContentObserver
:
类VolumeOnserver(上下文:context,h:Handler?):ContentObserver(h){
main活动
:
类MainActivity:AppCompatActivity(){
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.kortex.mediafix">
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<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">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name=".BootUpReceiver"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.QUICKBOOT_POWERON" />
<action android:name="com.kortex.mediafix.BootUpReceiver" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
<service android:name=".VolumeCheck" />
</application>
</manifest>
override fun onReceive(context: Context, intent: Intent) {
val myObserver = VolumeOnserver(context, Handler())
// Register the VolumeOnserver for setting changes
context.contentResolver.registerContentObserver(
android.provider.Settings.System.CONTENT_URI ,true,
myObserver)
}
}
private val context = context
override fun onChange(selfChange: Boolean) {
onChange(selfChange, uri = null)
}
// Implement the onChange(boolean, Uri) method to take advantage of the new Uri argument.
override fun onChange(selfChange: Boolean, uri: Uri?) {
// Handle change.
val audio = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
val level = audio.getStreamVolume(AudioManager.STREAM_MUSIC)
val maxVolume = audio.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
val percent = 0.2f
val twintyVolume = (maxVolume * percent).toInt()
if ( level > twintyVolume) audio.setStreamVolume(AudioManager.STREAM_MUSIC,twintyVolume,0)
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val audio = this.getSystemService(Context.AUDIO_SERVICE) as AudioManager
val level = audio.getStreamVolume(AudioManager.STREAM_MUSIC)
val maxVolume = audio.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
val percent = 0.2f
val twintyVolume = (maxVolume * percent).toInt()
if ( level > twintyVolume) audio.setStreamVolume(AudioManager.STREAM_MUSIC,twintyVolume,0)
finish()
}
}