广播分类

广播分为有序广播和无序广播

• 有序广播
  所有与广播中的action匹配的广播接收者都可以收到这条广播,但是是有先后顺序的,按照广播接收者的优先级排序.
• 无序广播
  所有与广播中的action匹配的广播接收者都可以收到这条广播,并且是没有先后顺序的,视为同时收到

有序广播

• sendOrderedBroadcast发送
• 可以添加最终广播接收者,最终广播接收者resultReceiver:不需要在清单文件中配置,这个广播接收者只接收该条有序广播,并且是最后一个收到该广播,并且一定可以接收到,即便被拦截

发出广播

public class MainActivity extends AppCompatActivity {

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


    public void click(View v) {
        Intent intent = new Intent();
        intent.setAction("orderlyBroadcast");

        //发送有序广播
        //sendOrderedBroadcast(intent, null, null, null, 0, "每人发100W", null);

        //最终广播接收者resultReceiver:不需要在清单文件中配置,这个广播接收者只接收该条有序广播,并且是最后一个收到该广播,并且一定可以接收到,即便被拦截
        sendOrderedBroadcast(intent, null, new MyResultReceiver(), null, 0, "每人发100W", null);
    }

    class MyResultReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            String str = getResultData();
            System.out.println("最终结果:" + str);
        }
    }
}

接收者

• 优先级 android:priority="300" 范围-1000 至 1000 1000为最高
• 阻止广播 abortBroadcast(),对于最终接收者来说,无效.

<receiver
    android:name=".LevelOneReceiver"
    android:enabled="true"
    android:exported="true">
    <intent-filter android:priority="1000">
        <action android:name="orderlyBroadcast"></action>
    </intent-filter>
</receiver>

<receiver
    android:name=".LevelTwoReceiver"
    android:enabled="true"
    android:exported="true">
    <intent-filter android:priority="600">
        <action android:name="orderlyBroadcast"></action>
    </intent-filter>
</receiver>

<receiver
    android:name=".LevelThreeReceiver"
    android:enabled="true"
    android:exported="true">
    <intent-filter android:priority="300">
        <action android:name="orderlyBroadcast"></action>
    </intent-filter>
</receiver>

public class LevelOneReceiver extends BroadcastReceiver {
    public LevelOneReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        String str = getResultData().toString();
        System.out.println("LEVEL ONE:" + str);

        //修改广播内容
        setResultData("每人发80W");
    }
}

public class LevelTwoReceiver extends BroadcastReceiver {
    public LevelTwoReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        String str = getResultData().toString();
        System.out.println("LEVEL TWO:" + str);
        //阻止广播后,优先级低的则收不到了,但最终广播接收者一定会收到.
        abortBroadcast();
    }
}

public class LevelThreeReceiver extends BroadcastReceiver {
    public LevelThreeReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        String str = getResultData().toString();
        System.out.println("LEVEL THREE:" + str);
    }
}