diff --git a/app/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java b/app/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java index ffe5d57..dab46e4 100644 --- a/app/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java +++ b/app/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java @@ -36,9 +36,9 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { public static final String NOTE = "note"; public static final String DATA = "data"; - } + }//接口定义note和data - private static final String TAG = "NotesDatabaseHelper"; + private static final String TAG = "NotesDatabaseHelper";//定义常量TAG private static NotesDatabaseHelper mInstance; @@ -61,7 +61,7 @@ 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" + - ")"; + ")";//创建数据库中需要存储的项目的名称，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 + "(" + @@ -76,11 +76,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," + DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," + DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" + - ")"; + ")";//创建数据库中需要存储的项目的名称，相当于创建一个表格的表头的内容 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 @@ -92,7 +92,7 @@ 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";//在文件夹中更新移入一个新的便签之后需要更改的数据的表格 /** * Decrease folder's note count when move note from folder @@ -105,7 +105,7 @@ 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";//在文件夹中更新移出一个旧的便签之后需要更改的数据的表格 /** * Increase folder's note count when insert new note to the folder @@ -117,7 +117,7 @@ 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";//是在文件夹中更新插入一个便签之后需要更改的数据的表格 /** * Decrease folder's note count when delete note from the folder @@ -130,7 +130,7 @@ 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";//是在文件夹中更新删除一个便签之后需要更改的数据的表格 /** * Update note's content when insert data with type {@link DataConstants#NOTE} @@ -143,7 +143,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT + " WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" + - " END"; + " END";//是在文件夹中对一个便签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 @@ -156,7 +156,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT + " WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" + - " END"; + " END";//是便签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 @@ -169,7 +169,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " UPDATE " + TABLE.NOTE + " SET " + NoteColumns.SNIPPET + "=''" + " WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" + - " END"; + " END";//是便签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 @@ -180,7 +180,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " BEGIN" + " DELETE FROM " + TABLE.DATA + " WHERE " + DataColumns.NOTE_ID + "=old." + NoteColumns.ID + ";" + - " END"; + " END";//是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 @@ -191,7 +191,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " BEGIN" + " DELETE FROM " + TABLE.NOTE + " WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" + - " END"; + " END";//是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 @@ -204,18 +204,18 @@ 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";//是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，初始化名称和版本 public void createNoteTable(SQLiteDatabase db) { db.execSQL(CREATE_NOTE_TABLE_SQL); reCreateNoteTableTriggers(db); createSystemFolder(db); Log.d(TAG, "note table has been created"); - } + }//存储标签的属性 private void reCreateNoteTableTriggers(SQLiteDatabase db) { db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update"); @@ -233,7 +233,7 @@ 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); - } + }//SQL主要是用来重新创建上述定义的表格用的，先删除上面原来有的trigger再重新创建新的数据库 private void createSystemFolder(SQLiteDatabase db) { ContentValues values = new ContentValues(); @@ -268,14 +268,14 @@ 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"); - } + }//存储标签内容 private void reCreateDataTableTriggers(SQLiteDatabase db) { db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_insert"); @@ -285,20 +285,21 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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); - } + }//SQL主要是用来重新创建上述定义的表格用的，先删除上面原来有的trigger再重新创建新的数据库 static synchronized NotesDatabaseHelper getInstance(Context context) { if (mInstance == null) { mInstance = new NotesDatabaseHelper(context); } return mInstance; - } + }//解决同一时刻只能有一个线程执行 + //需要一个类被所有的其它类使用，但又要求这个类只能被实例化一次 @Override public void onCreate(SQLiteDatabase db) { createNoteTable(db); createDataTable(db); - } + }//调用那两个表格 @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { @@ -331,14 +332,14 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { throw new IllegalStateException("Upgrade notes database to version " + newVersion + "fails"); } - } + }//更新版本 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 @@ -353,10 +354,10 @@ 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 }