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MiNote/data/NotesDatabaseHelper.java

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/*
* Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.micode.notes.data;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.DataConstants;
import net.micode.notes.data.Notes.NoteColumns;
public class NotesDatabaseHelper extends SQLiteOpenHelper {
// 数据库帮助类,用于管理名为 note.db 的 SQLite 数据库。
// 它继承自 SQLiteOpenHelper 类,这是 Android提供的一个方便的工具类用于管理数据库的创建和版本更新.
// 数据库的基本信息;数据库名称和版本信息(在创建实例对象时会用到)
private static final String DB_NAME = "note.db";
private static final int DB_VERSION = 5;
// 内部接口个人理解为两个表名一个note一个data
public interface TABLE {
public static final String NOTE = "note";
public static final String DATA = "data";
}
// 一个标签,方便日志输出时识别出信息来自哪里
private static final String TAG = "NotesDatabaseHelper";
private static NotesDatabaseHelper mInstance;
/* 以下都是一些SQL语句辅助我们来对数据库进行操作 */
// 创建note表的语句这里的NoteColumns就是我们刚刚在Notes中定义的一个接口里面定义了一系列静态的数据库表中的列名
private static final String CREATE_NOTE_TABLE_SQL =
"CREATE TABLE " + TABLE.NOTE + "(" +
NoteColumns.ID + " INTEGER PRIMARY KEY," +
NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +
NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," +
NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +
NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.PASSWORD + " TEXT DEFAULT NULL " +
")";
// 同上创建data表的语句这里的DataColumns就是我们刚刚在Notes中定义的一个接口里面定义了一系列静态的数据库表中的列名
private static final String CREATE_DATA_TABLE_SQL =
"CREATE TABLE " + TABLE.DATA + "(" +
DataColumns.ID + " INTEGER PRIMARY KEY," +
DataColumns.MIME_TYPE + " TEXT NOT NULL," +
DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA1 + " INTEGER," +
DataColumns.DATA2 + " INTEGER," +
DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
")";
// 功能简介:
// 创建一个以note的ID为索引
// 解读:
// 用于在TABLE.DATA表上创建一个名为note_id_index的索引。
// 这个索引是基于DataColumns.NOTE_ID列的。IF NOT EXISTS确保了如果索引已经存在那么就不会尝试重新创建它避免了可能的错误。
// 索引通常用于提高查询性能,特别是在对某个字段进行频繁查询时。
private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
"CREATE INDEX IF NOT EXISTS note_id_index ON " +
TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";
/* 以下是一些对便签增删改定义的触发器 */
/* 总结
* 这些触发器都是用来维护NOTE表和与之相关联的DATA表之间数据一致性的。
* 当在NOTE表中发生删除或更新操作时这些触发器会自动执行相应的数据清理或更新操作确保数据库中的数据保持正确和一致。
* 特别是在处理文件夹和回收站等逻辑时,这些触发器起到了非常重要的作用,可以自动管理数据的移动和删除。*/
/**
* Increase folder's note count when move note to the folder
*/
// 功能简介:
// 添加触发器:增加文件夹的便签个数记录(因为我们会移动便签进入文件夹,这时候文件夹的计数要进行更新)
// 解读:
// 定义了一个SQL触发器increase_folder_count_on_update。
// 触发器是一种特殊的存储过程它会在指定表上的指定事件如INSERT、UPDATE、DELETE发生时自动执行。
// 这个触发器会在TABLE.NOTE表的NoteColumns.PARENT_ID字段更新后执行。
// 触发器的逻辑是当某个笔记的PARENT_ID即父文件夹ID被更新时它会找到对应的文件夹通过新的PARENT_ID并将该文件夹的NOTES_COUNT即笔记数增加1。
private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER increase_folder_count_on_update "+
" AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
" BEGIN " +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
" WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
" END";
/**
* Decrease folder's note count when move note from folder
*/
// 功能简介:(触发器和上面的 “增加文件夹的便签个数记录” 同理,就不细节解读了)
// 添加触发器:减少文件夹的便签个数记录(因为我们会移动便签移出文件夹,这时候文件夹的计数要进行更新)
private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER decrease_folder_count_on_update " +
" AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
" BEGIN " +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
" WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
" AND " + NoteColumns.NOTES_COUNT + ">0" + ";" +
" END";
/**
* Increase folder's note count when insert new note to the folder
*/
// 功能简介:(触发器原理和上面的 “增加文件夹的便签个数记录” 同理,就不细节解读了)
// 添加触发器:当我们在文件夹插入便签时,增加文件夹的便签个数记录
private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
"CREATE TRIGGER increase_folder_count_on_insert " +
" AFTER INSERT ON " + TABLE.NOTE +
" BEGIN " +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
" WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
" END";
/**
* Decrease folder's note count when delete note from the folder
*/
// 功能简介:(触发器原理和上面的 “增加文件夹的便签个数记录” 同理,就不细节解读了)
// 添加触发器:当我们在文件夹删除便签时,减少文件夹的便签个数记录
private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
"CREATE TRIGGER decrease_folder_count_on_delete " +
" AFTER DELETE ON " + TABLE.NOTE +
" BEGIN " +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
" WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
" AND " + NoteColumns.NOTES_COUNT + ">0;" +
" END";
/**
* Update note's content when insert data with type {@link DataConstants#NOTE}
*/
// 功能简介:
// 添加触发器当向DATA表中插入类型为NOTE便签的数据时更新note表对应的笔记内容。
// 解读:
// 在DATA表上进行INSERT操作后如果新插入的数据的MIME_TYPE为NOTE则触发此操作。
// 它会更新NOTE表将与新插入数据相关联的标签的SNIPPET摘要字段设置为新插入数据的CONTENT字段的值
private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
"CREATE TRIGGER update_note_content_on_insert " +
" AFTER INSERT ON " + TABLE.DATA +
" WHEN new." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
" BEGIN" +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
" WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
" END";
/**
* Update note's content when data with {@link DataConstants#NOTE} type has changed
*/
// 功能简介:
// 添加触发器当DATA表中类型为NOTE便签的数据更改时更新note表对应的笔记内容。
// 解读:
// 在DATA表上进行UPDATE操作后如果更新前的数据的MIME_TYPE为NOTE则触发此操作。
// 它会更新NOTE表将与更新后的数据相关联的笔记的SNIPPET字段设置为新数据的CONTENT字段的值
private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER update_note_content_on_update " +
" AFTER UPDATE ON " + TABLE.DATA +
" WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
" BEGIN" +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
" WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
" END";
/**
* Update note's content when data with {@link DataConstants#NOTE} type has deleted
*/
// 功能简介:
// 添加触发器当从NOTE表中删除笔记时删除与该笔记相关联的数据就是删除data表中为该note的数据
// 解读:
// 在NOTE表上进行DELETE操作后此触发器被激活。
// 它会从DATA表中删除所有与已删除的笔记由old.ID表示相关联的数据行通过比较DATA表中的NOTE_ID字段与已删除笔记的ID来实现
private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
"CREATE TRIGGER update_note_content_on_delete " +
" AFTER delete ON " + TABLE.DATA +
" WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
" BEGIN" +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.SNIPPET + "=''" +
" WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" +
" END";
/**
* Delete datas belong to note which has been deleted
*/
// 功能简介:
// 添加触发器当从NOTE表中删除笔记时删除与该笔记相关联的数据就是删除data表中为该note的数据
// 解读:
// 在NOTE表上进行DELETE操作后此触发器被激活。
// 它会从DATA表中删除所有与已删除的笔记由old.ID表示相关联的数据行通过比较DATA表中的NOTE_ID字段与已删除笔记的ID来实现
private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
"CREATE TRIGGER delete_data_on_delete " +
" AFTER DELETE ON " + TABLE.NOTE +
" BEGIN" +
" DELETE FROM " + TABLE.DATA +
" WHERE " + DataColumns.NOTE_ID + "=old." + NoteColumns.ID + ";" +
" END";
/**
* Delete notes belong to folder which has been deleted
*/
// 功能简介:
// 添加触发器当从NOTE表中删除一个文件夹时删除该文件夹下的所有笔记。
// 解读:
// 在NOTE表上进行DELETE操作后如果删除的是一个文件夹由old.ID表示
// 触发器会删除所有以该文件夹为父级PARENT_ID的笔记通过比较NOTE表中的PARENT_ID字段与已删除文件夹的ID来实现
private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
"CREATE TRIGGER folder_delete_notes_on_delete " +
" AFTER DELETE ON " + TABLE.NOTE +
" BEGIN" +
" DELETE FROM " + TABLE.NOTE +
" WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
" END";
/**
* Move notes belong to folder which has been moved to trash folder
*/
// 功能简介:
// 添加触发器:当某个文件夹被移动到回收站时,移动该文件夹下的所有笔记到回收站
// 解读:
// 在NOTE表上进行UPDATE操作后如果某个文件夹的新PARENT_ID字段值等于回收站的IDNotes.ID_TRASH_FOLER
// 触发器会更新所有以该文件夹为父级PARENT_ID的笔记将它们也移动到回收站。
private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =
"CREATE TRIGGER folder_move_notes_on_trash " +
" AFTER UPDATE ON " + TABLE.NOTE +
" WHEN new." + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER +
" BEGIN" +
" UPDATE " + TABLE.NOTE +
" SET " + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER +
" WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
" END";
// 构造器
public NotesDatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
// 创建note标签
public void createNoteTable(SQLiteDatabase db) {
db.execSQL(CREATE_NOTE_TABLE_SQL);
reCreateNoteTableTriggers(db);
createSystemFolder(db);
Log.d(TAG, "note table has been created");
}
// 重新创建或更新与笔记表相关的触发器。
// 首先使用DROP TRIGGER IF EXISTS语句删除已存在的触发器。确保在重新创建触发器之前不存在同名的触发器。
// 然后使用db.execSQL()方法执行预定义的SQL语句这些语句用于创建新的触发器。
private void reCreateNoteTableTriggers(SQLiteDatabase db) {
db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update");
db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_update");
db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_delete");
db.execSQL("DROP TRIGGER IF EXISTS delete_data_on_delete");
db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_insert");
db.execSQL("DROP TRIGGER IF EXISTS folder_delete_notes_on_delete");
db.execSQL("DROP TRIGGER IF EXISTS folder_move_notes_on_trash");
db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER);
db.execSQL(NOTE_DELETE_DATA_ON_DELETE_TRIGGER);
db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER);
db.execSQL(FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER);
db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);
}
/* 以下部分是操作SQLite数据库部分 */
// 功能简介:
// 创建通话记录文件夹、默认文件夹、临时文件夹和回收站,并插入相关数据
// 具体解读:
// ContentValues是一个用于存储键值对的类常用于SQLite数据库的插入操作
// values.put方法可以向ContentValues对象中添加数据。
// NoteColumns.ID是存储文件夹ID的列名Notes.ID_CALL_RECORD_FOLDER是通话记录文件夹的ID。
// NoteColumns.TYPE是存储文件夹类型的列名Notes.TYPE_SYSTEM表示这是一个系统文件夹。
// 使用db.insert方法将values中的数据插入到TABLE.NOTE即标签表中。
// 每次插入新数据前都使用values.clear()方法清除ContentValues对象中的旧数据确保不会重复插入旧数据。
// 然后分别创建默认文件夹、临时文件夹和回收站,并以同样的方法插入数据。
private void createSystemFolder(SQLiteDatabase db) {
ContentValues values = new ContentValues();
/**
* call record foler for call notes
*/
values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
/**
* root folder which is default folder
*/
values.clear();
values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
/**
* temporary folder which is used for moving note
*/
values.clear();
values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
/**
* create trash folder
*/
values.clear();
values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
}
public void createDataTable(SQLiteDatabase db) {
db.execSQL(CREATE_DATA_TABLE_SQL);
reCreateDataTableTriggers(db);
db.execSQL(CREATE_DATA_NOTE_ID_INDEX_SQL);
Log.d(TAG, "data table has been created");
}
private void reCreateDataTableTriggers(SQLiteDatabase db) {
db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_insert");
db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_update");
db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_delete");
db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER);
db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER);
db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER);
}
static synchronized NotesDatabaseHelper getInstance(Context context) {
if (mInstance == null) {
mInstance = new NotesDatabaseHelper(context);
}
return mInstance;
}
@Override
public void onCreate(SQLiteDatabase db) {
createNoteTable(db);
createDataTable(db);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
boolean reCreateTriggers = false;
boolean skipV2 = false;
if (oldVersion == 1) {
upgradeToV2(db);
skipV2 = true; // this upgrade including the upgrade from v2 to v3
oldVersion++;
}
if (oldVersion == 2 && !skipV2) {
upgradeToV3(db);
reCreateTriggers = true;
oldVersion++;
}
if (oldVersion == 3) {
upgradeToV4(db);
oldVersion++;
}
if(oldVersion == 4){
upgradeToV5(db);
oldVersion++;
}
if (reCreateTriggers) {
reCreateNoteTableTriggers(db);
reCreateDataTableTriggers(db);
}
if (oldVersion != newVersion) {
throw new IllegalStateException("Upgrade notes database to version " + newVersion
+ "fails");
}
}
private void upgradeToV2(SQLiteDatabase db) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE);
db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA);
createNoteTable(db);
createDataTable(db);
}
private void upgradeToV3(SQLiteDatabase db) {
// drop unused triggers
db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_insert");
db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_delete");
db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_update");
// add a column for gtask id
db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.GTASK_ID
+ " TEXT NOT NULL DEFAULT ''");
// add a trash system folder
ContentValues values = new ContentValues();
values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
}
private void upgradeToV4(SQLiteDatabase db) {
db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
+ " INTEGER NOT NULL DEFAULT 0");
}
private void upgradeToV5(SQLiteDatabase db){
db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.PASSWORD
+ " TEXT DEFAULT NULL ");
}
}