Question

我正在设置一个关于如何对Android中的警报做出反应的骨架应用。当手机处于唤醒状态时，一切正常，当手机处于睡眠状态时，警报会触发（我甚至可以激活振动器），但屏幕保持关闭状态（完全黑色）。我不能破译为什么。欢迎任何帮助！

这是MainActivity中设置alarmManager的代码片段（E1是一个EditText，要求用户选择秒来触发警报）：

public void startAlarm(View view) {
    EditText E1 = (EditText) findViewById(R.id.et1);
    int i = Integer.parseInt(E1.getText().toString());
    Intent intent = new Intent(this, AlarmBroadcastReceiver.class);
    PendingIntent pending_intent = 
    PendingIntent.getBroadcast(this.getApplicationContext(),
        98989898, intent, 0); // 98989898 : some big number
    AlarmManager alarmManager = (AlarmManager) 
        getSystemService(ALARM_SERVICE);
    alarmManager.set(AlarmManager.RTC_WAKEUP, 
        System.currentTimeMillis() + i*1000, pending_intent);
    Toast.makeText(this, "Alarm set in: " + i + " seconds", 
    Toast.LENGTH_LONG).show();
}

alarmBroadcastReceiver会接收警报。它本身没有任何作用，它立即转移到UserResponseActivity：

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class AlarmBroadcastReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        // We're creating a new intent that's going to start the UserResponseActivity
        Intent in = new Intent(context, UserResponseActivity.class);
        // This boolean just makes it easier to check if the Activity has been started from
        // this class
        in.putExtra("lock", true);
        // You need to add this to your intent if you want to start an Activity fromm a class
        // that is not an Activity itself
        in.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        // Now we just start the Activity
        context.startActivity(in);
    }
}

然后UserResponseActivity是一个普通的活动，目前有来自Android Studio的样板画面。稍后我计划添加一些请求用户响应的代码。创建后，它会显示一个吐司并在短时间内激活振动器：

import android.content.Context;
import android.os.Bundle;
import android.os.Vibrator;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Toast;

public class UserResponseActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_response);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        /* Show a success toast*/
        Toast.makeText(this, "Alarm Started", Toast.LENGTH_LONG).show();
        /* Vibrate shortly */
        Vibrator vibrator = (Vibrator) this.getSystemService(Context.VIBRATOR_SERVICE);
        vibrator.vibrate(200);
    }

}

如果您需要它，我的清单中的代码行启用了警报接收器和振动器服务：

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

<receiver android:name=".AlarmBroadcastReceiver" />

如上所述，如果在手机唤醒时触发警报，一切正常：屏幕上显示UserResponseActivity，振动器熄灭。但是，如果在手机处于睡眠状态时触发警报，则振动器会熄灭（因此手机会被唤醒并调用UserResponseActivity），但屏幕会保持黑屏。当我随后打开手机时，UserResponseActivity就在那里。

我需要做些什么才能让UserResponseActivity 开启屏幕？

谢谢！

ADDED（在VicJordan回复后）：

@VicJordan：我将你的一段代码粘贴到了UserResponseActivity.java的onCreate中，如下所示，但得到两个错误，我无法找到我在这两行中做错了什么：

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
        activity.setTurnScreenOn(true);

a）Android Studio无法解析符号'O_MR1' b）它可以在第二行解决'活动'。我认为改变'this'的活动可以解决问题，但不是。我真的无法想出另一种方式来引用我所在的活动

public class UserResponseActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_response);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        // Turn on the screen
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
            activity.setTurnScreenOn(true);
        } else {
            final Window window = getWindow();
            window.addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
        }

        /* Show a success toast*/
        Toast.makeText(this, "Alarm Started", Toast.LENGTH_LONG).show();
        /* Vibrate shortly */
        Vibrator vibrator = (Vibrator) this.getSystemService(Context.VIBRATOR_SERVICE);
        vibrator.vibrate(200);
    }

你有什么建议吗？谢谢！

Answer 1

要在“活动”中打开屏幕，您可以使用WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON，但API级别27已弃用alias reset rm -rf composer.lock node_modules package-lock.json vendor composer install npm install gulp composer validate alias update rm -rf node_modules vendor composer install npm install composer update npm update reset标志，因此您可以从API级别27开始使用Activity.setTurnScreenOn(true)。

下面是代码：

FLAG_TURN_SCREEN_ON

查看此官方信息以获取更多信息：https://developer.android.com/training/scheduling/wakelock

警报后触发活动（RTC_WAKEUP）但屏幕仍为黑色

1 个答案: