Android广播

1.收发应用广播

1.标准广播

广播的收发过程分为三个步骤：

1. 发送标准广播
2. 定义广播接收器
3. 开关广播接收器

public class BroadStandardActivity extends AppCompatActivity implements View.OnClickListener {private StandardReceiver standardReceiver;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_broad_standard);findViewById(R.id.btn_send_standard).setOnClickListener(this);}@Overridepublic void onClick(View view) {Intent intent = new Intent("com.zzzjian.demo7.standard");sendBroadcast(intent);}@Overrideprotected void onStart() {super.onStart();standardReceiver = new StandardReceiver();// 创建意图过滤器 只处理 com.zzzjian.demo7.action.standard 这个动作IntentFilter filter = new IntentFilter(StandardReceiver.STANDARD_ACTION);// 注册接收器 注册之后才能正常接受广播registerReceiver(standardReceiver, filter);}@Overrideprotected void onStop() {super.onStop();// 注销接收器 注销之后就不再接受广播unregisterReceiver(standardReceiver);}
}

public class StandardReceiver extends BroadcastReceiver {private static final String TAG = "StandardReceiver";public   static final String STANDARD_ACTION = "com.zzzjian.demo7.standard";/*** 一旦收到标准广播，马上触发接收器的onReceive方法* @param context* @param intent*/@Overridepublic void onReceive(Context context, Intent intent) {if(intent != null && intent.getAction().equals(STANDARD_ACTION)){Log.d(TAG, "收到一个标准广播");}}
}

2.有序广播

• 一个广播存在多个接收器，这些接收器需要排队收听广播，这意味着该广播是条有序广播。
• 先收到广播的接收器，既可以让其他接收器继续收听广播，也可以中断广播不让其他接收器收听。

public class BroadOrderActivity extends AppCompatActivity implements View.OnClickListener {public static final String ORDER_ACTION = "com.zzzjian.demo7.order";private OrderAReceiver orderAReceiver;private OrderBReceiver orderBReceiver;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_broad_order);findViewById(R.id.btn_send_order).setOnClickListener(this);}@Overridepublic void onClick(View v) {Intent intent = new Intent(ORDER_ACTION);sendOrderedBroadcast(intent,null);}@Overrideprotected void onStart() {super.onStart();// 多个接收器处理有序广播的顺序规则// 1. 先处理优先级最高的接收器// 2. 优先级相同的接收器，先注册先处理orderAReceiver = new OrderAReceiver();IntentFilter filterA = new IntentFilter(ORDER_ACTION);filterA.setPriority(8);if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {registerReceiver(orderAReceiver, filterA, Context.RECEIVER_EXPORTED);}orderBReceiver = new OrderBReceiver();IntentFilter filterB = new IntentFilter(ORDER_ACTION);filterB.setPriority(10);if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {registerReceiver(orderBReceiver, filterB, Context.RECEIVER_EXPORTED);}}@Overrideprotected void onStop() {super.onStop();unregisterReceiver(orderAReceiver);unregisterReceiver(orderBReceiver);}
}

public class OrderAReceiver extends BroadcastReceiver {private static final String TAG = "OrderReceiver";@Overridepublic void onReceive(Context context, Intent intent) {if(intent != null && intent.getAction().equals(BroadOrderActivity.ORDER_ACTION)){Log.d(TAG, "收到一个有序广播A");}}
}

public class OrderBReceiver extends BroadcastReceiver {private static final String TAG = "OrderReceiver";@Overridepublic void onReceive(Context context, Intent intent) {if(intent != null && intent.getAction().equals(BroadOrderActivity.ORDER_ACTION)){Log.d(TAG, "收到一个有序广播B");// 中断广播abortBroadcast();}}
}

3.广播的静态注册

public class BroadStaticActivity extends AppCompatActivity implements View.OnClickListener {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_broad_static);findViewById(R.id.btn_send_shock).setOnClickListener(this);}@Overridepublic void onClick(View v) {// 8.0之后必须指定完整类名String fullName = "com.zzzjian.demo7.receiver.ShockReceiver";Intent intent = new Intent(ShockReceiver.SHOCK_ACTION);// 创建一个ComponentName对象，指定当前上下文和接收器全名ComponentName componentName = new ComponentName(this, fullName);intent.setComponent(componentName);sendBroadcast(intent);}
}

public class ShockReceiver extends BroadcastReceiver {public static final String SHOCK_ACTION = "com.zzzjian.demo7.shock";@Overridepublic void onReceive(Context context, Intent intent) {if(intent != null && intent.getAction().equals(SHOCK_ACTION)){Log.d("ShockReceiver", "震动");// 从系统服务获取震动管理器Vibrator vb = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);// 震动 500msvb.vibrate(500);}}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"><uses-permission android:name="android.permission.VIBRATE"/><applicationandroid:allowBackup="true"android:icon="@mipmap/ic_launcher"android:label="@string/app_name"android:roundIcon="@mipmap/ic_launcher_round"android:supportsRtl="true"android:theme="@style/Theme.MyApplication"><receiverandroid:name=".receiver.ShockReceiver"android:enabled="true"android:exported="true"><intent-filter><action android:name="com.zzzjian.demo7.shock" /></intent-filter></receiver><activityandroid:name=".BroadStaticActivity"android:exported="true"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter></activity></application></manifest>

2.监听系统广播

1.接受分钟到达广播

• Intent.ACTION_TIME_TICK

public class SystemMinteActivity extends AppCompatActivity {private TimeReceiver timeReceiver;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_system_minte);}@Overrideprotected void onStart() {super.onStart();timeReceiver = new TimeReceiver();IntentFilter filter = new IntentFilter(Intent.ACTION_TIME_TICK);registerReceiver(timeReceiver,filter);}@Overrideprotected void onStop() {super.onStop();unregisterReceiver(timeReceiver);}
}

public class TimeReceiver extends BroadcastReceiver {private static final String TAG = "TimeReceiver";@Overridepublic void onReceive(Context context, Intent intent) {if(intent != null){Log.d(TAG,"收到一个分钟到达的广播");}}
}

2.接受网络变更广播

• android.net.conn.CONNECTIVITY_CHANGE

getType：获取网络类型

网络类型	说明
TYPE_WIFI	无线热点WIFI
TYPE_MOBILE	数据连接
TYPE_WIMAX	WiMAX
TYPE_ETHERNET	以太网
TYPE_BLUETOOTH	蓝牙
TYPE_VPN	虚拟专用网络VPN

getTypeName：获取网络类型名称

getSubtype：获取网络的子类型。如果为数据连接时，子类型为2G/3G/4G等细分。

3.定时管理器AlarmManager

Android提供了专门的定时管理器AlarmManager，它利用系统闹钟定时发送广播，常见方法有：

• set：设置一次性定时器。
• setAndAllowWhileIdle：设置一次性定时器，即使设备处于空闲状态，也会保证执行定时器。
• setRepeating：设置重复定时器，但系统不保证按时发送广播。
• cancel：取消延迟意图的定时器。

public class AlarmActivity extends AppCompatActivity implements View.OnClickListener {private AlarmReceiver alarmReceiver;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_alarm);findViewById(R.id.btn_alarm).setOnClickListener(this);}@Overridepublic void onClick(View v) {alarmReceiver.sendAlarm();}protected void onStart() {// 调用父类的onStart方法super.onStart();// 创建AlarmReceiver实例，并传入当前应用的上下文// 这里假设AlarmReceiver是一个自定义的BroadcastReceiver子类alarmReceiver = new AlarmReceiver(getApplicationContext());// 创建IntentFilter对象，用于过滤接收到的广播// 指定接收的广播动作为AlarmReceiver.ALARM_ACTIONIntentFilter filter = new IntentFilter(AlarmReceiver.ALARM_ACTION);// 检查Android SDK版本是否大于等于Oreo（8.0）// Android Oreo引入了一些新的API和行为变化if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {// 注册BroadcastReceiver// 参数分别为：要注册的BroadcastReceiver实例、IntentFilter对象、注册标志// Context.RECEIVER_EXPORTED表示此BroadcastReceiver可以被其他应用访问registerReceiver(alarmReceiver, filter, Context.RECEIVER_EXPORTED);}}@Overrideprotected void onStop() {super.onStop();unregisterReceiver(alarmReceiver);}
}

public class AlarmReceiver extends BroadcastReceiver {public static final String ALARM_ACTION = "com.zzzjian.demo7.alarm";private final Context mContext;public AlarmReceiver(Context context){super();this.mContext = context;}@Overridepublic void onReceive(Context context, Intent intent) {if(intent != null && intent.getAction().equals(ALARM_ACTION)){Log.d("AlarmReceiver","收到一个闹钟的广播");}}public void sendAlarm(){// 创建一个Intent对象，指定动作类型为ALARM_ACTIONIntent intent = new Intent(ALARM_ACTION);// 创建一个PendingIntent对象，用于稍后触发Intent// 第二个参数为请求码，在此设置为0；第三个参数为Intent对象；第四个参数为标志位，设置为FLAG_IMMUTABLE表示PendingIntent不可变PendingIntent pendingIntent = PendingIntent.getBroadcast(mContext, 0, intent, PendingIntent.FLAG_IMMUTABLE);// 获取系统服务AlarmManager，用于管理定时任务AlarmManager alarmManager = (AlarmManager) mContext.getSystemService(Context.ALARM_SERVICE);// 设置定时任务，当设备空闲时也可以唤醒设备执行任务// 参数分别为：AlarmManager设置类型、触发时间（从1970年1月1日00:00:00 GMT开始计算的毫秒数）、待执行的PendingIntent// 注释掉的代码为另一种设置方式，不支持设备空闲时唤醒// alarmManager.set(AlarmManager.RTC_WAKEUP, 1000, pendingIntent);if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){alarmManager.setAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, 1000, pendingIntent);}else{alarmManager.set(AlarmManager.RTC_WAKEUP, 1000, pendingIntent);}}}

3.捕捉屏幕的变更事件

1.竖屏和横屏切换

为了避免横竖屏切换时重新加载界面的情况，Android设计了一种配置变更机制，在指定的环境配置发生变更之时，无需重启活动页面，只需执行特定的变更行为。该机制分为两步：

1. 修改AndroidManifest.xml，给activity节点增加android:configChange属性
2. 修改活动页面的Java代码，重写活动的onCinfigurationChanged方法，补充对应的代码处理逻辑。

onfigChanges属性的取值	说明
orientation	屏幕方向发生变化
screenLayout	屏幕的显示发生改变，例如在全屏和分屏之间切换
screenSize	屏幕大小发生改变，例如在竖屏和横屏之间切换
keyboard	键盘发生改变，例如使用了外部键盘
keyboardHidden	软键盘弹出或隐藏
navigation	导航方式发生改变，例如采用了轨迹球导航
fontSize	字体比例发生改变
locale	设备本地位置发生改变，例如切换了系统语言
uiMode	用户界面的模式发生改变，例如开启了夜间模式

<activityandroid:name=".ChangeDirectionActivity"android:exported="true"android:theme="@style/Theme.MyApplication"android:configChanges="orientation|screenLayout|screenSize"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter></activity>

public class ChangeDirectionActivity extends AppCompatActivity {private static final String TAG = "ChangeDirectionActivity";private TextView tv_monitor;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);EdgeToEdge.enable(this);setContentView(R.layout.activity_change_direction);tv_monitor = findViewById(R.id.tv_monitor);Log.d(TAG, "onCreate");}@Overridepublic void onConfigurationChanged(@NonNull Configuration newConfig) {super.onConfigurationChanged(newConfig);switch (newConfig.orientation){case Configuration.ORIENTATION_PORTRAIT:tv_monitor.setText("竖屏");break;case Configuration.ORIENTATION_LANDSCAPE:tv_monitor.setText("横屏");break;default:break;}}
}

2.回到桌面与切换到任务列表

• 按下主页键会回到桌面，按下任务键会打开任务列表，这两个操作并未提供相应的按键处理方法，而是通过广播发出事件信息。
• 如果想知道是否回到桌面，以及是否打开任务列表，均需收听系统广播Intent.ACTION_CLOSE_SYSTEM_DIALOGS。
• 从收到广播意图中获取原因reason字段，该字段值为homekey时表示回到桌面，值为recentapps时表示打开任务列表。

public class ReturnDesktopActivity extends AppCompatActivity {private DesktopReceiver desktopReceiver;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_return_desktop);desktopReceiver = new DesktopReceiver();IntentFilter filter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {registerReceiver(desktopReceiver,filter, Context.RECEIVER_EXPORTED);}}@Overrideprotected void onDestroy() {super.onDestroy();unregisterReceiver(desktopReceiver);}@Overridepublic void onPictureInPictureModeChanged(boolean isInPictureInPictureMode) {super.onPictureInPictureModeChanged(isInPictureInPictureMode);if(isInPictureInPictureMode){Log.d("ReturnDesktopActivity", "进入小窗模式");}else{Log.d("ReturnDesktopActivity", "退出小窗模式");}}private class DesktopReceiver extends BroadcastReceiver{@Overridepublic void onReceive(Context context, Intent intent) {if(intent != null && intent.getAction().equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)){String reason = intent.getStringExtra("reason");if(!TextUtils.isEmpty(reason) && (reason.equals("home") || reason.equals("recentapps"))){if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && !isInPictureInPictureMode()){PictureInPictureParams.Builder builder = new PictureInPictureParams.Builder();Rational aspectRatio = new Rational(10, 5);builder.setAspectRatio(aspectRatio);enterPictureInPictureMode(builder.build());}}}}}
}

<activityandroid:name=".ReturnDesktopActivity"android:configChanges="orientation|screenLayout|screenSize"android:exported="true"android:screenOrientation="portrait"android:supportsPictureInPicture="true"android:theme="@style/Theme.MyApplication"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter></activity>