new annotation

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
 }