添加了对NotesDatebaseHelper类的注释

app/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java

@@ -26,7 +26,9 @@ 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，对一些note和文件进行数据库的操作。
+ */
 public class NotesDatabaseHelper extends SQLiteOpenHelper {
     private static final String DB_NAME = "note.db";
 
@@ -42,6 +44,9 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     private static NotesDatabaseHelper mInstance;
 
+    /**
+     * 创建数据库中需要存储的项目的名称
+     */
     private static final String CREATE_NOTE_TABLE_SQL =
             "CREATE TABLE " + TABLE.NOTE + "(" +
                     NoteColumns.ID + " INTEGER PRIMARY KEY," +
@@ -63,6 +68,9 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
                     NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +
                     ")";
 
+    /**
+     * 功能同上，但存储的项目类型不同
+     */
     private static final String CREATE_DATA_TABLE_SQL =
             "CREATE TABLE " + TABLE.DATA + "(" +
                     DataColumns.ID + " INTEGER PRIMARY KEY," +
@@ -78,12 +86,16 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
                     DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
                     ")";
 
+    /**
+     * 创建用来存储便签编号的数据表格
+     */
     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
+     * 在文件夹中移入一个Note之后需要更改的数据的表格。
      */
     private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
             "CREATE TRIGGER increase_folder_count_on_update " +
@@ -96,6 +108,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Decrease folder's note count when move note from folder
+     * 在文件夹中移出一个Note之后需要更改的数据的表格。
      */
     private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
             "CREATE TRIGGER decrease_folder_count_on_update " +
@@ -109,6 +122,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Increase folder's note count when insert new note to the folder
+     * 在文件夹中插入一个Note之后需要更改的数据的表格。
      */
     private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
             "CREATE TRIGGER increase_folder_count_on_insert " +
@@ -121,6 +135,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Decrease folder's note count when delete note from the folder
+     * 在文件夹中删除一个Note之后需要更改的数据的表格。
      */
     private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
             "CREATE TRIGGER decrease_folder_count_on_delete " +
@@ -134,6 +149,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Update note's content when insert data with type {@link DataConstants#NOTE}
+     * 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。
      */
     private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
             "CREATE TRIGGER update_note_content_on_insert " +
@@ -147,6 +163,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Update note's content when data with {@link DataConstants#NOTE} type has changed
+     * Note数据被修改后需要更改的数据的表格。
      */
     private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
             "CREATE TRIGGER update_note_content_on_update " +
@@ -160,6 +177,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Update note's content when data with {@link DataConstants#NOTE} type has deleted
+     * Note数据被删除后需要更改的数据的表格
      */
     private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
             "CREATE TRIGGER update_note_content_on_delete " +
@@ -173,6 +191,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Delete datas belong to note which has been deleted
+     * 删除已删除的便签的数据后需要更改的数据的表格。
      */
     private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
             "CREATE TRIGGER delete_data_on_delete " +
@@ -184,6 +203,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     /**
      * Delete notes belong to folder which has been deleted
+     * 删除已删除的文件夹的便签后需要更改的数据的表格。
      */
     private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
             "CREATE TRIGGER folder_delete_notes_on_delete " +
@@ -208,8 +228,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     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*/
 
+    /**
+     *创建表格（用来存储标签属性）
+     */
     public void createNoteTable(SQLiteDatabase db) {
         db.execSQL(CREATE_NOTE_TABLE_SQL);
         reCreateNoteTableTriggers(db);
@@ -217,6 +240,9 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         Log.d(TAG, "note table has been created");
     }
 
+    /**
+     * 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 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");
@@ -294,6 +320,9 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         return mInstance;
     }
 
+    /**
+     * 实现上面创建的两个表格
+     */
     @Override
     public void onCreate(SQLiteDatabase db) {
         createNoteTable(db);