//数据库操作，SQLOpenhelper,对一些note和文件进行数据库的操作。比如删除文件后，将文件里的note也相应删除 package net.micode.notes.data; //保存一些数据信息，这些数据可以被数据库操作 import android.content.ContentValues; //加载和访问资源 import android.content.Context; //主要提供了对应于添加、删除、更新、查询的操作 import android.database.sqlite.SQLiteDatabase; //数据库的更新和创建 import android.database.sqlite.SQLiteOpenHelper; //安卓日志类接口 import android.util.Log; //导入Notes.java中的DataColumns, NoteColumns接口，和类DataConstants import net.micode.notes.data.Notes.DataColumns; import net.micode.notes.data.Notes.DataConstants; import net.micode.notes.data.Notes.NoteColumns; //继承于SQLiteOpenHelper的类NotesDatabaseHelper，用于实现对便签或者 文件的数据库操作，例如删除便签 public class NotesDatabaseHelper extends SQLiteOpenHelper { private static final String DB_NAME = "note.db"; private static final int DB_VERSION = 4; public interface TABLE { //接口，分成note和data，在后面的程序里分别使用过 public static final String NOTE = "note"; public static final String DATA = "data"; } //创建一个表格用来储存标签编号 private static final String TAG = "NotesDatabaseHelper"; //实例化一个NoteDatabaseHelper private static NotesDatabaseHelper mInstance; /** * 当创建一个新的便签，就产生了各类关于便签的信息， * 比如ID，父便签ID，背景颜色，创建日期等， * 我们需要把这些信息放入数据库，这就是数据库的表头。 * 我们在下面定义的涉及操作的字符串， * 全都是为了在之后执行db.execSQL("字符串")。 */ 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" + ")"; //大体同上，这里储存的是便签内容的信息， // 用这些信息作为数据库对便签内容存储的表头 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 ''" + ")"; //创建索引，名称为note_id_index，在TABLE.DATA表格的DataCloumns.NOTE_ID列 private static final String CREATE_DATA_NOTE_ID_INDEX_SQL = "CREATE INDEX IF NOT EXISTS note_id_index ON " + TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";//存储便签编号的一个数据表格 /** * Increase folder's note count when move note to the folder * 增加文件夹便签数量，当移动一个便签进入该文件夹后， * 之后在db.execSQL(字符串)中用到， * 启动自定义的数据库update触发器，有相关的一系列数据库操作。 */ 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 * 同上，从文件夹移除便签，文件夹便签数量减1， * 以后在db.execSQL(字符串)中用到， * 启动自定义的数据库updata触发器，附带相关的一系列操作 */ 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 * 文件夹中创建新便签，文件夹便签数量+1， * 启动自定义的数据库insert触发器，附带相关的一系列操作 */ 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 * 在文件夹中删除note时，更新文件夹的note数量 */ 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} * 当Note插入新的数据时，更新note的内容，并更改表格 */ 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 * 构建一条SQL语句，用于实现在note中改变data后，进行当前状态的更新 */ 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 * 当note的内容被删除时，更新表格 */ 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 * 删除数据库中的数据，当便签中的数据被删除时删除相应数据库 */ 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 * 删除属于已删除的文件夹中的便签的数据 */ 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 * 还原垃圾桶中便签后需要更改的数据的表格。 */ 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"; public NotesDatabaseHelper(Context context) { super(context, DB_NAME, null, DB_VERSION); } //构造函数，传入数据库的名称和版本 public void createNoteTable(SQLiteDatabase db) { db.execSQL(CREATE_NOTE_TABLE_SQL); reCreateNoteTableTriggers(db); createSystemFolder(db); Log.d(TAG, "note table has been created"); } //创建表格（用来存储标签属性） 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); } //execSQL是数据库操作的API，主要是更改行为的SQL语句。 //在这里主要是用来重新创建上述定义的表格用的，先删除原来有的数据库的触发器再重新创建新的数据库 private void createSystemFolder(SQLiteDatabase db) { ContentValues values = new ContentValues(); /** * call record foler for call notes * 初始化ContenValues实例，然后存入相应的通话记录文件夹类型形成映射， */ 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 * 对根文件夹修改，先将values实例的内容清空，然后存入values，再插入对象 */ 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 * 设置临时文件夹作为文件夹移动的有效目标 */ 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 * 创建垃圾文件夹 */ values.clear(); values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER); values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); db.insert(TABLE.NOTE, null, values); } //创建几个系统文件夹 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"); }//创建表格（用来存储标签内容） 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); }//创建用于表格初始化，删除触发器，然后更新触发器 static synchronized NotesDatabaseHelper getInstance(Context context) { if (mInstance == null) { mInstance = new NotesDatabaseHelper(context); } return mInstance; } //上网查是为解决同一时刻只能有一个线程执行. //在写程序库代码时，有时有一个类需要被所有的其它类使用， //但又要求这个类只能被实例化一次，是个服务类，定义一次，其它类使用同一个这个类的实例 @Override public void onCreate(SQLiteDatabase db) { createNoteTable(db); createDataTable(db); }//实现两个表格（上面创建的两个表格） @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { //是否重建的信号 boolean reCreateTriggers = false; //是否从V2升级到V3 boolean skipV2 = false; //判断旧版本是不是V1，如果是就升级版本到V2 if (oldVersion == 1) { upgradeToV2(db); skipV2 = true; // this upgrade including the upgrade from v2 to v3 oldVersion++; } //判断旧版本是V2，且未跳过V2版本，就升级版本到V3 if (oldVersion == 2 && !skipV2) { upgradeToV3(db); reCreateTriggers = true; oldVersion++; } //如果旧版本是V3，就升级版本到V4 if (oldVersion == 3) { upgradeToV4(db); oldVersion++; } //若重构触发器的值为真，那么， // 要把便签（note）和数据（data）表单的数据库触发器重构，调用以上的定义 if (reCreateTriggers) { reCreateNoteTableTriggers(db); reCreateDataTableTriggers(db); } //旧版本与最新版本不一致，抛出异常 if (oldVersion != newVersion) { throw new IllegalStateException("Upgrade notes database to version " + newVersion + "fails"); } } //数据库版本的更新（数据库内容的更改） 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); } //更新到V2版本,删除note和data表，然后新建表 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); } //更新到V3版本，删除触发器，新增gtask和trash行，然后在表中增添表头 private void upgradeToV4(SQLiteDatabase db) { db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0"); }//更新到V4版本,但是不知道V2、V3、V4是什么意思 }