Android通过AlarmManager类实现简单闹钟功能

public class AlarmReceiver extends BroadcastReceiver {

 @Override
 public void onReceive(Context context, Intent intent) {
  Toast.makeText(context, "您设置的时间到了！",
   Toast.LENGTH_SHORT).show();
 }
}

public class MainActivity extends Activity {
 private Button btnSet, btnCancel;
 private TextView info;
 private Calendar calendar;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  btnSet = (Button) findViewById(R.id.setalarm);
  btnCancel = (Button) findViewById(R.id.cancelalarm);
  info = (TextView) findViewById(R.id.info);

  calendar = Calendar.getInstance();

  btnSet.setOnClickListener(new OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    calendar.setTimeInMillis(System.currentTimeMillis());
    int mHour = calendar.get(Calendar.HOUR_OF_DAY);
    int mMinute = calendar.get(Calendar.MINUTE);
    new TimePickerDialog(MainActivity.this,
      new TimePickerDialog.OnTimeSetListener() {
       @Override
       public void onTimeSet(TimePicker view,
         int hourOfDay, int minute) {
        // TODO Auto-generated method stub
        calendar.setTimeInMillis(System.currentTimeMillis());
        calendar.set(Calendar.HOUR_OF_DAY, hourOfDay);
        calendar.set(Calendar.MINUTE, minute);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        // 建立Intent和PendingIntent来调用目标组件
        Intent intent = new Intent(MainActivity.this, AlarmReceiver.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0);
        // 获取闹钟管理的实例
        AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
        // 设置闹钟
        am.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);
        // 设置周期闹钟
        am.setRepeating(AlarmManager.RTC_WAKEUP,
          System.currentTimeMillis() + (10 * 1000),
          (24 * 60 * 60 * 1000), pendingIntent);
        String tmpS = "设置闹钟时间为" + format(hourOfDay)
          + ":" + format(minute);
        info.setText(tmpS);
       }
      }, mHour, mMinute, true).show();
   }
  });

  btnCancel.setOnClickListener(new OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    Intent intent = new Intent(MainActivity.this,
      AlarmReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(
      MainActivity.this, 0, intent, 0);
    // 获取闹钟管理实例
    AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
    // 取消
    am.cancel(pendingIntent);
    info.setText("闹钟已经取消");
   }
  });
 }

 // 格式化字符串7:3-->07:03
 private String format(int x) {
  String s = "" + x;
  if (s.length() == 1) {
   s = "0" + s;
  }
  return s;
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.activity_main, menu);
  return true;
 }

}