A.apk

1.在MainActivity

private  Button  but;


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

        but=findViewById(R.id.bu_t);

        but.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //点击的时候发送一条广播出去
                Intent intent = new Intent("com.example.test2");//括号里为包名
                intent.putExtra("123", "我被点了");
                intent.setComponent(new ComponentName("com.rfid.RFID","com.rfid.RFID.MyReceiver"));//括号里为包名+广播类
                sendBroadcast(intent);
                Log.e(TAG, "onClick: 111111");

            }
        });

    }

2.XML

<Button
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="发送广播"
        android:id="@+id/bu_t"
        android:layout_centerInParent="true"
        />

B.apk

3.mainfest中隐世广播

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.rfid.RFID">

    <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>

<!--隐世广播-->
        <receiver
            android:name=".MyReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.rfid.RFID"/>
            </intent-filter>
        </receiver>

    </application>

</manifest>

4.新建MyReceiver类继承BroadcastReceiver 广播

public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,"接收到广播",Toast.LENGTH_SHORT).show();
        String str = intent.getStringExtra("123");
        Toast.makeText(context,str,Toast.LENGTH_SHORT).show();
    }
}

如果是定义内部类在MainActivity,必须要静态static ,否则会崩,调不到textview只需要加上静态static

private static TextView tex;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tex = (TextView) findViewById(R.id.tex);
    }



    public static class MyReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
            Toast.makeText(context,"接收到广播",Toast.LENGTH_SHORT).show();
            String str = intent.getStringExtra("123");
            Toast.makeText(context,str,Toast.LENGTH_SHORT).show();
            tex.setText(str);
        }
    }