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法律研究如何在 Android 中设置一个在给定日期和时间触发的警报？
此示例演示如何在 Android 中创建一个在指定日期和时间触发的警报。
步骤 1 - 在 Android Studio 中创建一个新项目，转到文件 ⇒ 新建项目，并填写所有必需的详细信息以创建新项目。
步骤 2 - 将以下代码添加到 res/layout/activity_main.xml 中。
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity"> </LinearLayout>
步骤 3 - 将以下代码添加到 src/MainActivity.java 中
package app.com.sample;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.DialogFragment;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.app.TimePickerDialog;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TimePicker;
import java.text.DateFormat;
import java.util.Calendar;
import java.util.Objects;
public class MainActivity extends AppCompatActivity implements TimePickerDialog.OnTimeSetListener{
String timeText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DialogFragment timePicker = new TimePickerFragment();
timePicker.show(getSupportFragmentManager(), "time picker");
}
@Override
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
Calendar c = Calendar.getInstance();
c.set(Calendar.HOUR_OF_DAY, hourOfDay);
c.set(Calendar.MINUTE, minute);
c.set(Calendar.SECOND, 0);
updateTimeText(c);
startAlarm(c);
}
private void updateTimeText(Calendar c) {
timeText = "Alarm set for: ";
timeText += DateFormat.getTimeInstance(DateFormat.SHORT).format(c.getTime());
}
private void startAlarm(Calendar c) {
AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(this, NotificationPublisher.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 1, intent, 0);
if (c.before(Calendar.getInstance())) {
c.add(Calendar.DATE, 1);
}
Objects.requireNonNull(alarmManager).setExact(AlarmManager.RTC_WAKEUP,
c.getTimeInMillis(), pendingIntent);
}
}步骤 4 - 创建一个名为 NotificationPublisher 的新类，并添加以下代码
package app.com.sample;
import android.app.Notification;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import androidx.core.app.NotificationCompat;
public class NotificationPublisher extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
NotificationHelper notificationHelper = new NotificationHelper(context);
NotificationCompat.Builder nb = notificationHelper.getChannelNotification();
notificationHelper.getManager().notify(1, nb.build());
Notification notification = nb.build();
notification.defaults |= Notification.DEFAULT_VIBRATE;
notification.defaults |= Notification.DEFAULT_SOUND;
}
}步骤 5 - 创建一个名为 NotificaitonHelper 的新类，并添加以下代码
package app.com.sample;
import android.annotation.TargetApi;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.content.Context;
import android.content.ContextWrapper;
import android.os.Build;
import androidx.core.app.NotificationCompat;
class NotificationHelper extends ContextWrapper {
public static final String channelID = "channelID";
public static final String channelName = "Channel Name";
private NotificationManager notificationManager;
public NotificationHelper(Context base) {
super(base);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
createChannel();
}
}
@TargetApi(Build.VERSION_CODES.O)
private void createChannel() {
NotificationChannel channel = new NotificationChannel(channelID, channelName,
NotificationManager.IMPORTANCE_HIGH);
getManager().createNotificationChannel(channel);
}
public NotificationManager getManager() {
if (notificationManager == null) {
notificationManager = (NotificationManager)
getSystemService(Context.NOTIFICATION_SERVICE);
}
return notificationManager;
}
public NotificationCompat.Builder getChannelNotification() {
return new NotificationCompat.Builder(getApplicationContext(), channelID)
.setContentTitle("Scheduled Alert")
.setContentText("Your Alert is Ringing")
.setSmallIcon(R.drawable.ic_alarm);
}
}步骤 6 - 创建一个名为 TimePickerFragment 的新类，并添加以下代码
package app.com.sample;
import android.app.Dialog;
import android.app.TimePickerDialog;
import android.os.Bundle;
import android.text.format.DateFormat;
import java.util.Calendar;
import androidx.annotation.NonNull;
import androidx.fragment.app.DialogFragment;
public class TimePickerFragment extends DialogFragment {
@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
Calendar c = Calendar.getInstance();
int hour = c.get(Calendar.HOUR_OF_DAY);
int minute = c.get(Calendar.MINUTE);
return new TimePickerDialog(getActivity(), (TimePickerDialog.OnTimeSetListener) getActivity(),
hour, minute, DateFormat.is24HourFormat(getActivity()));
}
}步骤 7 - 将以下代码添加到 androidManifest.xml 中
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample"> <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> <receiver android:name=".NotificationPublisher"></receiver> </application>
让我们尝试运行您的应用程序。我假设您已将您的实际 Android 移动设备连接到您的计算机。要从 Android Studio 运行应用程序，请打开您的项目之一的活动文件，然后点击工具栏中的运行 
图标。选择您的移动设备作为选项，然后检查您的移动设备，它将显示您的默认屏幕 -
更新于： 2020-07-07
848 次查看
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