使用服务注册特殊广播接收者
Android中的广播:系统在运行过程中,会发生很多事件,系统为了让其他应用知道系统发生了这个事件,会发送一个对应事件的广播,比如:电量改变,收到短信,拨打电话,屏幕解锁,系统开机,只有注册一个广播接收者,就可以接收到系统发送的广播。
屏幕锁屏和解锁、电量改变等广播属于安卓系统中操作特别频繁的广播事件,若在MainActivity中注册,当MainActivity销毁时无法接收广播,所以应该在服务中去注册广播接收者,必须使用代码注册!
首先这是定义的广播接收者:
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
//获取当前事件类型
String action = intent.getAction();
if("android.intent.action.SCREEN_OFF".equals(action)){
//屏幕锁屏
System.out.println("屏幕锁屏");
}else if("android.intent.action.SCREEN_ON".equals(action)){
//屏幕解锁
System.out.println("屏幕解锁");
}
}
}
动态注册广播的Service:
import android.app.Service;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;
public class ScreenService extends Service {
private MyReceiver myReceiver;
public ScreenService() {
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
//获取MyReceiver实例
myReceiver = new MyReceiver();
//添加Action
IntentFilter filter = new IntentFilter();
filter.addAction("android.intent.action.SCREEN_OFF");
filter.addAction("android.intent.action.SCREEN_ON");
//动态注册广播
registerReceiver(myReceiver,filter);
super.onCreate();
}
@Override
public void onDestroy() {
//当服务销毁的时候取消注册广播
unregisterReceiver(myReceiver);
super.onDestroy();
}
}
MainActivity在加载的时候就开启服务:
package useservice.xpu.nevergiveup.serviceresgitreceiver;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startService(new Intent(getApplicationContext(),
ScreenService.class));
}
}
之后别忘记配置一下Service
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="useservice.xpu.nevergiveup.serviceresgitreceiver">
<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>
<service android:name=".ScreenService"/>
</application>
</manifest>