Android 中使用AlarmManager设置闹钟详解

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".AlarmManagerActivity">
    <TimePicker
        android:id="@+id/timePicker"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/btn_alarm"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/timePicker"
        android:layout_centerHorizontal="true"
        android:text="设置闹钟" />
</RelativeLayout>

public class AlarmActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
        alertDialog.setTitle("传递正能量")
                .setIcon(R.drawable.ic_baseline_report)
                .setMessage("要么出众，要么出局")
                .setNegativeButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        //确定
                    }
                }).show();
    }
}

public class AlarmManagerActivity extends AppCompatActivity {
    private TimePicker timePicker;
    private Button btn_alarm;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_alarm_manager);
        timePicker = findViewById(R.id.timePicker);
        btn_alarm = findViewById(R.id.btn_alarm);
        btn_alarm.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //设置闹钟
                Intent intent = new Intent(AlarmManagerActivity.this, AlarmActivity.class);
                //获取显示闹钟的PendingIntent
                //PendingIntent是对Intent的描述，主要用来处理即将发生的事情，这个Intent会由其他程序进行调用，这里是由闹钟调用
                PendingIntent pendingIntent = PendingIntent.getActivity(AlarmManagerActivity.this, 0, intent, 0);
                //获取AlarmManager对象
                AlarmManager alarm = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
                //获取日历对象
                Calendar c = Calendar.getInstance();
                //设置闹钟的小时数
                c.set(Calendar.HOUR_OF_DAY, timePicker.getHour());
                //设置闹钟的分钟数
                c.set(Calendar.MINUTE, timePicker.getMinute());
                //设置闹钟的秒数
                c.set(Calendar.SECOND, 0);
                //第一个参数：闹钟类型
                //ELAPSED_REALTIME:在指定的延时后提醒（不唤醒系统）
                //ELAPSED_REALTIME_WAKEUP:在指定的延时后提醒（唤醒系统）
                //RTC：到达指定时间提醒（不唤醒系统）
                //RTC_WAKEUP:到达指定时间提醒（唤醒系统）
                //第二参数:指定时间，获取日历对象对应时间的毫秒数
                //第三个参数：用于指定当闹钟唤醒时，所指定的页面
                alarm.set(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), pendingIntent);
                Toast.makeText(AlarmManagerActivity.this, "闹钟设置成功！", Toast.LENGTH_SHORT).show();
            }
        });
    }
}