From 13d9adb01db478e40fe36a52342a98bc1efd86cb Mon Sep 17 00:00:00 2001 From: puavjn2x9 <3530152719@qq.com> Date: Mon, 4 Dec 2023 10:57:53 +0800 Subject: [PATCH] Update NotesDatabaseHelper.java --- .../notes/data/NotesDatabaseHelper.java | 67 +++++++++---------- 1 file changed, 33 insertions(+), 34 deletions(-) diff --git a/src/net/micode/notes/data/NotesDatabaseHelper.java b/src/net/micode/notes/data/NotesDatabaseHelper.java index ffe5d57..d12400e 100644 --- a/src/net/micode/notes/data/NotesDatabaseHelper.java +++ b/src/net/micode/notes/data/NotesDatabaseHelper.java @@ -16,23 +16,23 @@ 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;//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。 +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 { private static final String DB_NAME = "note.db"; private static final int DB_VERSION = 4; - 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"; @@ -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" + - ")"; + ")";//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 + "(" + @@ -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 ''" + - ")"; + ")";//数据库中需要存储的项目的名称，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 @@ -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 @@ -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 @@ -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";//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 @@ -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";//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} @@ -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";//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 @@ -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";//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 @@ -169,7 +169,7 @@ 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 @@ -180,7 +180,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " 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 @@ -191,7 +191,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { " 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 @@ -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";//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"); @@ -233,8 +233,8 @@ 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。 + //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(); @@ -244,7 +244,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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 */ @@ -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"); @@ -285,20 +285,19 @@ 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); - } + }//同上面的execSQL 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. @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) { @@ -331,14 +330,14 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { 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 @@ -353,10 +352,10 @@ 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