Android学习之四大组件之广播接收器BroadcastReceiver
BroadcastReceiver顾名思义也就是说"广播接收器"的意思，它用来接收系统和应用中的广播。作为四大组件之一想必大家肯定比我更熟悉。
BroadcastReceiver的注册方式有2种：
1.静态注册：
静态注册是在AndroidManifest.xml中配置的，例如
<receiver android:name=".StaticReceiver"> <intent-filter> <action android:name="com.yuzhentao.staticaction" /> </intent-filter> </receiver>
之后只要是
"com.yuzhentao.staticaction"
这个地址的广播，StaticReceiver都能收到，StaticReceiver代码如下
/** * 静态广播的BroadcastReceiver * * @author yuzhentao */ public class StaticReceiver extends BroadcastReceiver {
@Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_STATIC)) {
SharedPreferences.Editor et = context.getSharedPreferences(Constants.SP_NAME, Context.MODE_PRIVATE).edit(); et.putString(Constants.SP_KEY_STATIC, intent.getStringExtra(Constants.MSG_STATIC)); et.apply(); }
}
}
这里通过SharedPreferences将收到的消息存储起来，同时我将一些常用的常量提取出来写在了一个类里面，方便使用，个人习惯呵呵。常量类如下
/** * 常量 * * @author yuzhentao */ public class Constants {
public static final String ACTION_STATIC = "com.yuzhentao.staticaction"; public static final String ACTION_DYNAMIC = "com.yuzhentao.dynamicaction"; public static final String ACTION_DISORDERLY= "com.yuzhentao.disorderlyaction"; public static final String ACTION_ORDERLY= "com.yuzhentao.orderlyaction"; public static final String MSG_STATIC = "msg_static"; public static final String MSG_DYNAMIC = "msg_dynamic"; public static final String MSG_DISORDERLY = "msg_disorderly"; public static final String MSG_ORDERLY = "msg_orderly"; public static final String SP_NAME = "sp_name"; public static final String SP_KEY_STATIC = "sp_key_static"; }
这样MainActivity中就能获取到收到的广播，MainActivity中肯定是要做发送广播的操作。我们可以设置通过点击Button的方式来发送广播。
case R.id.button_static_activity_main:
Intent intentStatic = new Intent(Constants.ACTION_STATIC); intentStatic.putExtra(Constants.MSG_STATIC, "收到静态广播"); sendBroadcast(intentStatic); sendStaticMsg(); break;
这里有个sendStaticMsg()，通过异步的方式来显示文本也就是说收到的消息。
/** * 发送静态广播的消息 */ private void sendStaticMsg() {
handlerStatic.post(new StaticRunnable()); }
/** * 静态广播的Runnable */ private class StaticRunnable implements Runnable {
@Override public void run() {
tvStatic.setText(sp.getString(Constants.SP_KEY_STATIC, "")); }
}
2.动态注册：
动态注册需要在代码中指定广播并注册和注销，先在MainActivity中声明一个BroadcastReceiver，如下
private BroadcastReceiver broadcastReceiverStatic = new BroadcastReceiver() {
@Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_DYNAMIC)) {
tvDynamic.setText(intent.getStringExtra(Constants.MSG_DYNAMIC)); }
}
};
在onCreate()中注册广播，MainActivity创建广播就注册
IntentFilter intentFilter = new IntentFilter(Constants.ACTION_DYNAMIC); registerReceiver(broadcastReceiverStatic, intentFilter);
在onDestroy()中注销广播，MainActivity销毁广播就注销
unregisterReceiver(broadcastReceiverStatic);
点击Button来发送广播
case R.id.button_dynamic_activity_main:
Intent intentDynamic = new Intent(Constants.ACTION_DYNAMIC); intentDynamic.putExtra(Constants.MSG_DYNAMIC, "收到动态广播"); sendBroadcast(intentDynamic); break;
之后声明的BroadcastReceiver的onReceiver()中就会收到广播。
BroadcastReceiver有2种：
1.无序广播：
无序广播就是普通的广播，不需要声明优先级，这里用静态注册的方式来演示下无序广播的效果，先创建3个BroadcastReceiver，如下
/** * 无序广播的BroadcastReceiver1 * * @author yuzhentao */ public class DisorderlyReceiver1 extends BroadcastReceiver {
@Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_DISORDERLY)) {
String msg = intent.getStringExtra(Constants.MSG_DISORDERLY); Log.e("DisorderlyReceiver1", msg); }
}
}
/** * 无序广播的BroadcastReceiver2 * * @author yuzhentao */ public class DisorderlyReceiver2 extends BroadcastReceiver {
@Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_DISORDERLY)) {
String msg = intent.getStringExtra(Constants.MSG_DISORDERLY); Log.e("DisorderlyReceiver2", msg); }
}
}
/** * 无序广播的BroadcastReceiver3 * * @author yuzhentao */ public class DisorderlyReceiver3 extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_DISORDERLY)) {
String msg = intent.getStringExtra(Constants.MSG_DISORDERLY); Log.e("DisorderlyReceiver3", msg); }
}
}
别忘记在AndroidManifest.xml中配置
<receiver android:name=".DisorderlyReceiver1"> <intent-filter> <action android:name="com.yuzhentao.disorderlyaction" /> </intent-filter> </receiver> <receiver android:name=".DisorderlyReceiver2"> <intent-filter> <action android:name="com.yuzhentao.disorderlyaction" /> </intent-filter> </receiver> <receiver android:name=".DisorderlyReceiver3"> <intent-filter> <action android:name="com.yuzhentao.disorderlyaction" /> </intent-filter> </receiver>
然后点击按钮发送广播
case R.id.button_disorderly_activity_main:
Intent intentDisorderly = new Intent(Constants.ACTION_DISORDERLY); intentDisorderly.putExtra(Constants.MSG_DISORDERLY, "收到无序广播"); sendBroadcast(intentDisorderly); break;
然后运行，打印Log
02-28 11:09:04.015 13861-13861/com.yuzhentao.broadcastreceiverdemo E/DisorderlyReceiver1: 收到无序广播
02-28 11:09:04.017 13861-13861/com.yuzhentao.broadcastreceiverdemo E/DisorderlyReceiver2: 收到无序广播
02-28 11:09:04.018 13861-13861/com.yuzhentao.broadcastreceiverdemo E/DisorderlyReceiver3: 收到无序广播
无序广播对于多个接收者来说是完全异步的，通常每个接收者都无需等待即可以接收到广播，接收者相互之间不会有影响。对于这种广播，接收者无法终止广播，即无法阻止其他接收者的接收动作。也就是说我们在onReceiver()即使加上
abortBroadcast();
也是没有卵用的
2.有序广播：
同样采用静态注册，先创建3个BroadcastReceiver，如下
/** * 有序广播的BroadcastReceiver1 * * @author yuzhentao */ public class OrderlyReceiver1 extends BroadcastReceiver {
@Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_ORDERLY)) {
String msg = intent.getStringExtra(Constants.MSG_ORDERLY); Log.e("OrderlyReceiver1", msg); Bundle bundle = new Bundle(); bundle.putString(Constants.MSG_ORDERLY, msg + "@OrderlyReceiver1"); setResultExtras(bundle); // abortBroadcast(); }
}
}
/** * 有序广播的BroadcastReceiver2 * * @author yuzhentao */ public class OrderlyReceiver2 extends BroadcastReceiver {
@Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_ORDERLY)) {
String msg = getResultExtras(true).getString(Constants.MSG_ORDERLY); Log.e("OrderlyReceiver2", msg); Bundle bundle = new Bundle(); bundle.putString(Constants.MSG_ORDERLY, msg + "@OrderlyReceiver2"); setResultExtras(bundle); }
}
}
/** * 有序广播的BroadcastReceiver3 * * @author yuzhentao */ public class OrderlyReceiver3 extends BroadcastReceiver {
@Override public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Constants.ACTION_ORDERLY)) {
String msg = getResultExtras(true).getString(Constants.MSG_ORDERLY); Log.e("OrderlyReceiver3", msg); }
}
}
这里使用setResultExtras()来加工下收到的消息，为了方便演示。不同的地方在于AndroidManifest.xml中的配置，使用sendOrderedBroadcast()方法发送有序广播时，需要一个权限参数，如果为null则表示不要求接收者声明指定的权限，如果不为null，则表示接收者若要接收此广播，需声明指定权限。这样做是从安全角度考虑的，例如系统的短信就是有序广播的形式，一个应用可能是具有拦截垃圾短信的功能，当短信到来时它可以先接受到短信广播，必要时终止广播传递，这样的软件就必须声明接收短信的权限。
所以我们在AndroidMainfest.xml中定义一个权限：
<permission android:name="yuzhentao.permission.MY_BROADCAST_PERMISSION" android:protectionLevel="normal" /> <uses-permission android:name="yuzhentao.permission.MY_BROADCAST_PERMISSION" />
然后广播注册时当然也要加上优先级了，优先级范围为-1000到1000，数值越大优先级越高
<receiver android:name=".OrderlyReceiver1"> <intent-filter android:priority="1000"> <action android:name="com.yuzhentao.orderlyaction" /> </intent-filter> </receiver> <receiver android:name=".OrderlyReceiver2"> <intent-filter android:priority="999"> <action android:name="com.yuzhentao.orderlyaction" /> </intent-filter> </receiver> <receiver android:name=".OrderlyReceiver3"> <intent-filter android:priority="998"> <action android:name="com.yuzhentao.orderlyaction" /> </intent-filter> </receiver>
最后是点击Button发送广播
case R.id.button_orderly_activity_main:
Intent intentOrderly = new Intent(Constants.ACTION_ORDERLY); intentOrderly.putExtra(Constants.MSG_ORDERLY, "收到有序广播"); sendOrderedBroadcast(intentOrderly, "yuzhentao.permission.MY_BROADCAST_PERMISSION"); // sendOrderedBroadcast(intentOrderly, null); break;
运行，打印Log
02-28 11:19:19.373 25914-25914/com.yuzhentao.broadcastreceiverdemo E/OrderlyReceiver1: 收到有序广播
02-28 11:19:19.375 25914-25914/com.yuzhentao.broadcastreceiverdemo E/OrderlyReceiver2: 收到有序广播@OrderlyReceiver1
02-28 11:19:19.377 25914-25914/com.yuzhentao.broadcastreceiverdemo E/OrderlyReceiver3: 收到有序广播@OrderlyReceiver1@OrderlyReceiver2
如果OrderlyReceiver1使用了
abortBroadcast();
效果如下
02-28 11:19:19.373 25914-25914/com.yuzhentao.broadcastreceiverdemo E/OrderlyReceiver1: 收到有序广播
好了，到此结束。希望对大家有所帮助。
效果图：
