Android如何发送跨进程广播，代码怎么写

Android中发送跨进程广播需要使用到Binder机制，下面是一份简单的代码实现：

1. 创建一个自定义的广播接收器类MyBroadcastReceiver，继承自BroadcastReceiver，用于处理接收到的广播消息。

public class MyBroadcastReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        String message = intent.getStringExtra("message");
        Log.d("MyBroadcastReceiver", "Received message: " + message);
    }
}

2. 在发送端进程中，创建一个远程服务MyService，它会在onCreate()方法中注册一个广播接收器MyBroadcastReceiver。

public class MyService extends Service {

    private MyBroadcastReceiver receiver;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        receiver = new MyBroadcastReceiver();
        IntentFilter filter = new IntentFilter("com.example.broadcasttest.ACTION");
        registerReceiver(receiver, filter);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        unregisterReceiver(receiver);
    }
}

3. 在发送端进程中，启动MyService服务，并使用Intent发送广播消息。

// 启动MyService服务
Intent intent = new Intent(this, MyService.class);
startService(intent);

// 发送广播消息
Intent broadcastIntent = new Intent("com.example.broadcasttest.ACTION");
broadcastIntent.putExtra("message", "Hello, world!");
sendBroadcast(broadcastIntent);

4. 在接收端进程中，创建一个远程服务MyService，它会在onCreate()方法中注册一个广播接收器MyBroadcastReceiver，并将这个广播接收器的Stub对象传递给发送端进程。

public class MyService extends Service {

    private MyBroadcastReceiver receiver;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return new MyBinder();
    }

    @Override
    public void onCreate() {
        super.onCreate();
        receiver = new MyBroadcastReceiver();
        IntentFilter filter = new IntentFilter("com.example.broadcasttest.ACTION");
        registerReceiver(receiver, filter);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        unregisterReceiver(receiver);
    }

    private class MyBinder extends IMyBroadcastReceiver.Stub {
        @Override
        public void onReceive(Intent intent) throws RemoteException {
            receiver.onReceive(MyService.this, intent);
        }
    }
}

5. 在接收端进程中，创建一个远程服务连接对象MyServiceConnection，用于连接到发送端进程中的MyService服务，并获取该服务返回的MyBinder对象。

private IMyBroadcastReceiver myBinder;

private ServiceConnection connection = new ServiceConnection() {
    @Override
    public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
        myBinder = IMyBroadcastReceiver.Stub.asInterface(iBinder);
    }

    @Override
    public void onServiceDisconnected(ComponentName componentName) {
        myBinder = null;
    }
};

// 启动MyService服务
Intent intent = new Intent(this, MyService.class);
bindService(intent, connection, Context.BIND_AUTO_CREATE);

6. 在接收端进程中，使用MyBinder对象的onReceive()方法接收广播消息。

if (myBinder != null) {
    Intent intent = new Intent();
    intent.putExtra("message", "Hello, world!");
    myBinder.onReceive(intent);
}

以上就是一份简单的跨进程广播的代码实现，需要注意的是：

1. 在发送端进程和接收端进程中都需要创建一个远程服务，并分别注册一个广播接收器。

2. 在接收端进程中，通过MyBinder对象的Stub实现类将广播消息传递给广播接收器处理。