Android菜鸟练习第二十二课 Broadcast的基本使用

public class FirstReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String content = intent.getStringExtra("msg");
        Toast.makeText(context,content,Toast.LENGTH_SHORT).show();
    }

      

2.Manifest文件中application路径下添加如下代码      

//静态注册为常驻型，也就是说当应用关闭后，如果有广播信息传来，MyReceiver也会被系统调用而自动运行      

<receiver android:name=".FirstReceiver">
    <intent-filter>
        <action android:name="android.intent.action.MY_BROADCAST"/>//发送广播时的频道
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</receiver>      

public class SecondReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String content = intent.getStringExtra("MSG");
        Toast.makeText(context,content,Toast.LENGTH_SHORT).show();
    }      
    
}      
       

public class MainActivity extends AppCompatActivity {
    SecondReceiver secondReceiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.btn_first).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setAction("android.intent.action.MY_BROADCAST");
                intent.putExtra("msg","这是第静态注册的广播信息");
                sendBroadcast(intent);
            }
        });

        //动态注册广播
        secondReceiver = new SecondReceiver();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("android.intent.action.SECOND_BROADCAST");
        registerReceiver(secondReceiver,intentFilter);

        findViewById(R.id.btn_second).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent("android.intent.action.SECOND_BROADCAST");
                intent.putExtra("MSG","这是动态注册广播接收到的消息");
                sendBroadcast(intent);
            }
        });
    }

    //动态注册广播当activity或者service销毁时没有接触注册系统会报异常
    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(secondReceiver);
    }
}
      
    
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn_first"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:text="向FirstReceiver发送消息" />

    <Button
        android:id="@+id/btn_second"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:text="向SecondReceiver发送第一个消息" />

</LinearLayout>