diff --git a/notes/data/NotesDatabaseHelper.java b/notes/data/NotesDatabaseHelper.java index 342f6ce..60865bb 100644 --- a/notes/data/NotesDatabaseHelper.java +++ b/notes/data/NotesDatabaseHelper.java @@ -15,39 +15,33 @@ */ 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.content.ContentValues;//就是用于保存一些数据（string boolean byte double float int long short ...）信息，这些信息可以被数据库操作时使用。 +import android.content.Context;//加载和访问资源。（android中主要是这两个功能，但是这里具体不清楚） +import android.database.sqlite.SQLiteDatabase;//主要提供了对应于添加、删除、更新、查询的操作方法： insert()、delete()、update()和query()。配合content.values +import android.database.sqlite.SQLiteOpenHelper;//用来管理数据的创建和版本更新 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; - - +//数据库操作，用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 + public class NotesDatabaseHelper extends SQLiteOpenHelper { - //定义数据名称 private static final String DB_NAME = "note.db"; - - //定义数据库版本 + private static final int DB_VERSION = 4; - - //定义TABLE接口 - public interface TABLE { + + 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"; } - - - //定义标签 + private static final String TAG = "NotesDatabaseHelper"; - + private static NotesDatabaseHelper mInstance; - - //定义了SQL语句分别用于创建便签表、数据表、包含ID、便签和数据的表格 + private static final String CREATE_NOTE_TABLE_SQL = "CREATE TABLE " + TABLE.NOTE + "(" + NoteColumns.ID + " INTEGER PRIMARY KEY," + @@ -67,9 +61,8 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," + NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" + - ")"; - - // + ")";//数据库中需要存储的项目的名称，就相当于创建一个表格的表头的内容。 + private static final String CREATE_DATA_TABLE_SQL = "CREATE TABLE " + TABLE.DATA + "(" + DataColumns.ID + " INTEGER PRIMARY KEY," + @@ -83,16 +76,15 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," + DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," + DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" + - ")"; - + ")";//和上面的功能一样，主要是存储的项目不同 + private static final String CREATE_DATA_NOTE_ID_INDEX_SQL = "CREATE INDEX IF NOT EXISTS note_id_index ON " + - TABLE.DATA + "(" + DataColumns.NOTE_ID + ");"; - + 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 */ - //将笔记移动到文件夹时增加文件夹的笔记数 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 + @@ -100,12 +92,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" + " WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" + - " END"; - + " END";//在文件夹中移入一个Note之后需要更改的数据的表格。 + /** * Decrease folder's note count when move note from folder */ - //从文件夹中移动笔记时减少文件夹的笔记计数 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 + @@ -114,12 +105,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" + " WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID + " AND " + NoteColumns.NOTES_COUNT + ">0" + ";" + - " END"; - + " END";//在文件夹中移出一个Note之后需要更改的数据的表格。 + /** * Increase folder's note count when insert new note to the folder */ - //在文件夹中插入新笔记时增加文件夹的笔记数 private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER = "CREATE TRIGGER increase_folder_count_on_insert " + " AFTER INSERT ON " + TABLE.NOTE + @@ -127,12 +117,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" + " WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" + - " END"; - + " END";//在文件夹中插入一个Note之后需要更改的数据的表格。 + /** * Decrease folder's note count when delete note from the folder */ - private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER = "CREATE TRIGGER decrease_folder_count_on_delete " + " AFTER DELETE ON " + TABLE.NOTE + @@ -141,12 +130,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" + " WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID + " AND " + NoteColumns.NOTES_COUNT + ">0;" + - " END"; - + " END";//在文件夹中删除一个Note之后需要更改的数据的表格。 + /** * Update note's content when insert data with type {@link DataConstants#NOTE} */ - //插入类型为｛DataConstants.Note｝的数据时更新注释的内容 private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER = "CREATE TRIGGER update_note_content_on_insert " + " AFTER INSERT ON " + TABLE.DATA + @@ -155,12 +143,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT + " WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" + - " END"; - + " END";//在文件夹中对一个Note导入新的数据之后需要更改的数据的表格。 + /** * Update note's content when data with {@link DataConstants#NOTE} type has changed */ - //当｛DataConstants.Note｝类型的数据发生更改时，更新注释的内容 private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER = "CREATE TRIGGER update_note_content_on_update " + " AFTER UPDATE ON " + TABLE.DATA + @@ -169,12 +156,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT + " WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" + - " END"; - + " END";//Note数据被修改后需要更改的数据的表格。 + /** * Update note's content when data with {@link DataConstants#NOTE} type has deleted */ - //删除｛DataConstants.Note｝类型的数据后，更新注释的内容 private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER = "CREATE TRIGGER update_note_content_on_delete " + " AFTER delete ON " + TABLE.DATA + @@ -183,36 +169,33 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.SNIPPET + "=''" + " WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" + - " END"; - + " END";//Note数据被删除后需要更改的数据的表格。 + /** * Delete datas belong to note which has been deleted */ - //删除数据属于已删除的注释 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"; - + " END";//删除已删除的便签的数据后需要更改的数据的表格。 + /** * Delete notes belong to folder which has been deleted */ - //删除笔记属于已删除的文件夹 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"; - + " END";//删除已删除的文件夹的便签后需要更改的数据的表格。 + /** * Move notes belong to folder which has been moved to trash folder */ - //移动笔记属于已移动到垃圾文件夹的文件夹 private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER = "CREATE TRIGGER folder_move_notes_on_trash " + " AFTER UPDATE ON " + TABLE.NOTE + @@ -221,19 +204,19 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER + " WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" + - " END"; - + " END";//还原垃圾桶中便签后需要更改的数据的表格。 + 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"); @@ -242,7 +225,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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); @@ -250,18 +233,19 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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 */ 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 */ @@ -269,7 +253,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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 */ @@ -277,7 +261,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER); values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); db.insert(TABLE.NOTE, null, values); - + /** * create trash folder */ @@ -285,78 +269,80 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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); - } - + }//同上面的execSQL + 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) { 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 (reCreateTriggers) { reCreateNoteTableTriggers(db); reCreateDataTableTriggers(db); } - + 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 + private void upgradeToV3(SQLiteDatabase db) { // drop unused triggers db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_insert"); @@ -370,10 +356,10 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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 + 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 }