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gitProject/src/main/java/net/micode/notes/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;
//数据库帮助类,用于辅助创建、处理数据库的条目
public class NotesDatabaseHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "note.db";//数据库名字
private static final int DB_VERSION = 4;//数据库版本
public interface TABLE {
//接口类,定义数据库表的便签和数据
public static final String NOTE = "note";
public static final String DATA = "data";
}
private static final String TAG = "NotesDatabaseHelper";//定义该类的名称
private static NotesDatabaseHelper mInstance;//实例化对象
//创建标签表表头并初始化
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" +
")";
//创建数据表表头并初始化
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 ''" +
")";
//对数据表创建索引以便签的ID作为数据库的ID用来做数据库ID的索引
private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
"CREATE INDEX IF NOT EXISTS note_id_index ON " +
TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";
/**
* Increase folder's note count when move note to the folder
*/
//创建触发器当把便签移入文件夹时,文件夹的便签数量+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
*/
//创建触发器当把便签移出文件夹时,减少文件夹的便签数量-1
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
*/
//创建触发器当把便签插入到文件夹时,文件夹的便签数量+1
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
*/
//创建触发器当把便签从文件夹删除时,文件夹的便签数量-1
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}
*/
//创建触发器当向note插入数据时更新note的内容并更改表格内容
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
*/
//创建触发器当note数据改变时更新note的内容并更改表格内容
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
*/
//创建触发器当note数据被删除时更新note的内容并更改表格内容
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
*/
//创建触发器,删除已经被删除的便签的数据
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
*/
//创建触发器,删除已经被删除的文件夹的便签
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
*/
//创建触发器,移出已近被移到垃圾文件夹中的便签
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";
//构造函数,传入数据库的名称和版本
public NotesDatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
//创建数据库并且自动执行create方法并且定义了下面的属性。
public void createNoteTable(SQLiteDatabase db) {
db.execSQL(CREATE_NOTE_TABLE_SQL);
reCreateNoteTableTriggers(db);
createSystemFolder(db);
Log.d(TAG, "note table has been created");
}
//如果触发器存在则drop然后再次创建触发器
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);
}
//创建系统文件夹
private void createSystemFolder(SQLiteDatabase db) {
ContentValues values = new ContentValues();//创建对象记录基本数据的值
/**
* call record foler for call notes呼叫记录文件夹
*/
values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);//放入数据(NoteColumns的id,呼叫记录文件夹的ld
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);//将note的文件夹类型与要放入数据库记录的格式类型映射形成values的键-值
db.insert(TABLE.NOTE, null, values);//向数据库的note表中插入数据
/**
* root folder which is default folder默认文件夹
*/
values.clear();//清空值且以下步骤与上述相同
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为移动note而设置的临时文件夹
*/
values.clear();//清空值且以下步骤与上述相同
values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
/**
* create trash folder创建垃圾回收文件夹
*/
values.clear();////清空值且以下步骤与上述相同
values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
}
//创建数据库并且自动执行create方法并且定义了下面的属性。
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");
}
//如果触发器存在则drop然后再次创建触发器
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);
}
/*如果NotesDatabaseHelper的实例创建失败那就重新建一个重新分配内从空间
static synchronized限制线程同时访问该实例*/
static synchronized NotesDatabaseHelper getInstance(Context context) {
if (mInstance == null) {
mInstance = new NotesDatabaseHelper(context);
}
return mInstance;
}
//onCreat方法创建note和data表
public void onCreate(SQLiteDatabase db) {
createNoteTable(db);
createDataTable(db);
}
//当打开数据库时传入的版本号与当前的版本号不同时会调用该方法,更新版本
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
boolean reCreateTriggers = false;//是否重建
boolean skipV2 = false;//是否从V2升级到V3
if (oldVersion == 1) {//版本是1
upgradeToV2(db);//更新到2
skipV2 = true; // this upgrade including the upgrade from v2 to v3
oldVersion++;
}
if (oldVersion == 2 && !skipV2) {//版本是2且没有跳过2号版本就更新到3号版本
upgradeToV3(db);//更新到3
reCreateTriggers = true;
oldVersion++;
}
if (oldVersion == 3) {//版本是3
upgradeToV4(db);//更新到4
oldVersion++;
}
if (reCreateTriggers) {//如果重新创建触发器,则重新创建两个表的触发器
reCreateNoteTableTriggers(db);
reCreateDataTableTriggers(db);
}
if (oldVersion != newVersion) {//如果旧版本不等于新版本则抛出更新版本失败错误
throw new IllegalStateException("Upgrade notes database to version " + newVersion
+ "fails");
}
}
//更新数据库到版本2
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);
}
//更新数据库到版本3
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);
}
//更新数据库到版本4
private void upgradeToV4(SQLiteDatabase db) {
db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
+ " INTEGER NOT NULL DEFAULT 0");
}
}