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/*
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* Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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*
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* @ProjectName: $MiNotes$
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* @Package: $ui$
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* @ClassName: $AlarmInitReciver.java$
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* @Description: 该类主要功能是根据数据库里的闹钟时间创建一个闹钟机制
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* @Author: 石兆羲
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* @CreateDate: $2023/12/23$
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*/
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package net.micode.notes.ui;
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import android.app.AlarmManager;
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import android.app.PendingIntent;
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import android.content.BroadcastReceiver;
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import android.content.ContentUris;
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import android.content.Context;
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import android.content.Intent;
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import android.database.Cursor;
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import net.micode.notes.data.Notes;
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import net.micode.notes.data.Notes.NoteColumns;
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public class AlarmInitReceiver extends BroadcastReceiver {
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private static final String [] PROJECTION = new String [] {
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NoteColumns.ID,
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NoteColumns.ALERTED_DATE
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};
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//对数据库的操作，作用是调用ID和设定的闹钟时间
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private static final int COLUMN_ID = 0;
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private static final int COLUMN_ALERTED_DATE = 1;
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@Override
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public void onReceive(Context context, Intent intent) {
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long currentDate = System.currentTimeMillis();
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//System.currentTimeMillis()函数的作用是产生一个当前的毫秒
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//毫秒数是自1970年1月1日0时起的毫秒数
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Cursor c = context.getContentResolver().query(Notes.CONTENT_NOTE_URI,
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//Cursor在这里的作用是通过查找数据库中的标签内容，找到和当前系统时间相等的标签
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//通过 context.getContentResolver() 获取当前应用程序的 ContentResolver 对象
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//使用 query() 方法对系统中的 Notes 数据库进行查询操作。
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//其中，Notes.CONTENT_NOTE_URI 是一个常量，表示 Notes 数据库中的笔记表对应的 Uri 地址。
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PROJECTION,//字符串数组，包含查询结果的列名
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NoteColumns.ALERTED_DATE + ">? AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE,
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//这里定义了两个查询条件：
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//笔记的提醒日期晚于某个特定时间；
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//笔记的类型为 Notes.TYPE_NOTE
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new String[] { String.valueOf(currentDate) },
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//将long变量currentDate转化为字符串
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null);
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if (c != null) {
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if (c.moveToFirst()) {
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do {
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long alertDate = c.getLong(COLUMN_ALERTED_DATE);
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Intent sender = new Intent(context, AlarmReceiver.class);
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//Intent用于在不同组件之间传递消息、启动服务、启动活动等。
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sender.setData(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, c.getLong(COLUMN_ID)));
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PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, sender, 0);
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//PendingIntent通常用于在未来的某个时间点执行某项操作，比如在特定的时刻启动一个 Activity、发送一个广播或者启动一个服务。
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AlarmManager alermManager = (AlarmManager) context
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.getSystemService(Context.ALARM_SERVICE);
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alermManager.set(AlarmManager.RTC_WAKEUP, alertDate, pendingIntent);
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//AlarmManager用于在指定的时间点触发某个操作。它可以用来实现定时任务、闹钟提醒、周期性任务等功能。
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//通过网上查找资料发现，对于闹钟机制的启动，通常需要上面的几个步骤，如新建Intent、PendingIntent以及AlarmManager等
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} while (c.moveToNext());
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}
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c.close();
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}
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}
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}
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