分类

标准广播(Normal broadcasts)是一种完全异步执行的广播，在广播发出后，所有的广播接收器都在同一时刻受到这条广播消息，没有先后顺序。效率高，无法被截断。

有序广播(Ordered broadcasts)是一种同步执行的广播，同一时刻，只有一个广播接收器能受到这条广播消息，当这个广播接收器中的逻辑执行完毕后，广播才会继续传递。
有先后顺序，优先级高的会先收到广播消息，并且前面的广播接收器可以截断正在传递的广播。

接受广播：广播接收器(Broadcast Receiver)

系统广播

注册广播

动态注册的广播接收器一定要取消注册，一般是在onDestroy()方法中通过调用unregisterReceiver()方法来实现的。

动态注册

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public class MainActivity extends AppCompatActivity {

    private IntentFilter mIntentFilter;
    // Whether there is a Wi-Fi connection.
    private static boolean wifiConnected = false;
    // Whether there is a mobile connection.
    private static boolean mobileConnected = false;

    private TextView mWifiTextView;
    private TextView mMobileTextView;

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

        mWifiTextView=(TextView)findViewById(R.id.wifi);
        mMobileTextView=(TextView)findViewById(R.id.mobile_network);
        /*
        注册广播接收器
        当网络发生变化时，系统发出的是一条值为"android.net.conn.CONNECTIVITY_CHANGE"的广播消息
         */
        mIntentFilter=new IntentFilter();
        mIntentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        mNetworkChangeReceiver=new NetworkChangeReceiver();
        registerReceiver(mNetworkChangeReceiver,mIntentFilter);

    }


    //注册的广播接收都需要解除注册
    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(mNetworkChangeReceiver);
    }

    class NetworkChangeReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
//            Toast.makeText(context,"network change",Toast.LENGTH_SHORT).show();
            ConnectivityManager connMgr =
                    (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo activeInfo = connMgr.getActiveNetworkInfo();

            if (activeInfo != null && activeInfo.isConnected()) {
                wifiConnected = activeInfo.getType() == ConnectivityManager.TYPE_WIFI;
                mobileConnected = activeInfo.getType() == ConnectivityManager.TYPE_MOBILE;
                if(wifiConnected) {
//                    Toast.makeText(context,"wifi is connected",Toast.LENGTH_LONG).show();
                    mWifiTextView.setText("Wifi is connected");
                    mMobileTextView.setText("mobile network is not connected");
                } else if (mobileConnected) {
//                    Toast.makeText(context,"mobile network is connected",Toast.LENGTH_LONG).show();
                    mWifiTextView.setText("Wifi is not connected");
                    mMobileTextView.setText("mobile network is connected");
                }
            } else {
//                Toast.makeText(context,"no network",Toast.LENGTH_LONG).show();
                mWifiTextView.setText("Wifi is not connected");
                mMobileTextView.setText("mobile network is not connected");
            }
        }
    }
}

另外还需在增加以下两个权限，否则会在打开的时候崩溃。

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<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

效果

静态注册

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public class BootCompleteReceiver extends BroadcastReceiver{

    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,"Boot Complete",Toast.LENGTH_LONG).show();
    }
}

在AndroidManifest.xml中需要添加下列语句：

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<user-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
......
<application
	...>
	.....

    <receiver android:name=".BootCompleteReceiver">
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED"/>
        </intent-filter>
    </receiver>

</application>

自定义广播

写一个自定义的广播接收器

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public class MyBroadcastReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,"received in MyBroadcastReceiver", Toast.LENGTH_LONG).show();
    }
}

发出一个广播

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Intent intent=new Intent("com.jc.broadcast_1.MY_BROADCAST");
sendBroadcast(intent);

在一个应用程序中发出的广播，也是可以被其它应用程序所接收到的。

发送有序广播

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sendOrderedBroadcast(Intent intent,String receiverPermission);

这样可以截断广播，
在onReceiver(...)方法里调用abortBroadcast()方法，就表示将这条广播截断。后面的广播就无法再接收到这条广播。

本地广播

只能在应用程序的内部进行传递，并且广播接收器也只能接受来自本应用发出的广播。

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mLocalBroadcastManager=LocalBroadcastManager.getInstance(this);

button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Intent intent=new Intent("com.jc.broadcast_2.LOCAL_BROADCAST");
        mLocalBroadcastManager.sendBroadcast(intent);
    }
});

mIntentFilter=new IntentFilter();
mIntentFilter.addAction("com.jc.broadcast_2.LOCAL_BROADCAST");
mLocalReceiver=new LocalReceiver();
mLocalBroadcastManager.registerReceiver(mLocalReceiver,mIntentFilter);