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陈念焯注释

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cnz
cnz 3 months ago
parent 0043f8dc7c
commit 6c4c4e3359
1 changed files with 127 additions and 60 deletions
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src/net/micode/notes/data/NotesDatabaseHelper.java
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@ -14,7 +14,9 @@
* limitations under the License.
*/
package net.micode.notes.data;
//这个类是整个笔记应用的数据存储核心，负责数据库的创建、维护和升级，确保数据的一致性和完整性。
package net.micode.notes.data;//导入包
import android.content.ContentValues;
import android.content.Context;
@ -26,64 +28,81 @@ import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.DataConstants;
import net.micode.notes.data.Notes.NoteColumns;
/**
* 笔记应用的数据库帮助类，负责数据库的创建和版本管理
*/
public class NotesDatabaseHelper extends SQLiteOpenHelper {
// 数据库名称常量
private static final String DB_NAME = "note.db";
// 数据库版本号
private static final int DB_VERSION = 4;
/**
* 数据库表名常量接口
*/
public interface TABLE {
// 笔记表名
public static final String NOTE = "note";
// 数据表名
public static final String DATA = "data";
}
// 日志标签
private static final String TAG = "NotesDatabaseHelper";
// 单例实例
private static NotesDatabaseHelper mInstance;
/**
* 创建笔记表的SQL语句
*/
private static final String CREATE_NOTE_TABLE_SQL =
"CREATE TABLE " + TABLE.NOTE + "(" +
NoteColumns.ID + " INTEGER PRIMARY KEY," +
NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +
NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," +
NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +
NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +
NoteColumns.ID + " INTEGER PRIMARY KEY," + // 笔记ID
NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + // 父文件夹ID
NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," + // 提醒日期
NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," + // 背景颜色ID
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 创建日期
NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," + // 是否有附件
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 修改日期
NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," + // 包含笔记数量(对文件夹)
NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," + // 内容摘要
NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," + // 类型(笔记/文件夹)
NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," + // 小部件ID
NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," + // 小部件类型
NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," + // 同步ID
NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," + // 本地修改标记
NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + // 原始父ID
NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," + // Google任务ID
NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" + // 版本号
")";
/**
* 创建数据表的SQL语句
*/
private static final String CREATE_DATA_TABLE_SQL =
"CREATE TABLE " + TABLE.DATA + "(" +
DataColumns.ID + " INTEGER PRIMARY KEY," +
DataColumns.MIME_TYPE + " TEXT NOT NULL," +
DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," +
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA1 + " INTEGER," +
DataColumns.DATA2 + " INTEGER," +
DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
DataColumns.ID + " INTEGER PRIMARY KEY," + // 数据ID
DataColumns.MIME_TYPE + " TEXT NOT NULL," + // MIME类型
DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," + // 关联的笔记ID
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 创建日期
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 修改日期
DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," + // 内容
DataColumns.DATA1 + " INTEGER," + // 数据字段1(整型)
DataColumns.DATA2 + " INTEGER," + // 数据字段2(整型)
DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," + // 数据字段3(文本)
DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," + // 数据字段4(文本)
DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" + // 数据字段5(文本)
")";
/**
* 在数据表上创建笔记ID索引的SQL语句
*/
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
* 触发器：当更新笔记的父文件夹ID时，增加新文件夹的笔记计数
*/
private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER increase_folder_count_on_update "+
@ -95,7 +114,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Decrease folder's note count when move note from folder
* 触发器：当更新笔记的父文件夹ID时，减少旧文件夹的笔记计数
*/
private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER decrease_folder_count_on_update " +
@ -108,7 +127,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Increase folder's note count when insert new note to the folder
* 触发器：当插入新笔记时，增加父文件夹的笔记计数
*/
private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
"CREATE TRIGGER increase_folder_count_on_insert " +
@ -120,7 +139,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Decrease folder's note count when delete note from the folder
* 触发器：当删除笔记时，减少父文件夹的笔记计数
*/
private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
"CREATE TRIGGER decrease_folder_count_on_delete " +
@ -133,7 +152,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Update note's content when insert data with type {@link DataConstants#NOTE}
* 触发器：当插入笔记数据时，更新笔记的内容摘要
*/
private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
"CREATE TRIGGER update_note_content_on_insert " +
@ -146,7 +165,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Update note's content when data with {@link DataConstants#NOTE} type has changed
* 触发器：当更新笔记数据时，更新笔记的内容摘要
*/
private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER update_note_content_on_update " +
@ -159,7 +178,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Update note's content when data with {@link DataConstants#NOTE} type has deleted
* 触发器：当删除笔记数据时，清空笔记的内容摘要
*/
private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
"CREATE TRIGGER update_note_content_on_delete " +
@ -172,7 +191,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Delete datas belong to note which has been deleted
* 触发器：当删除笔记时，删除关联的数据
*/
private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
"CREATE TRIGGER delete_data_on_delete " +
@ -183,7 +202,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Delete notes belong to folder which has been deleted
* 触发器：当删除文件夹时，删除该文件夹下的所有笔记
*/
private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
"CREATE TRIGGER folder_delete_notes_on_delete " +
@ -194,7 +213,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END";
/**
* Move notes belong to folder which has been moved to trash folder
* 触发器：当文件夹被移动到回收站时，将其下的所有笔记也移动到回收站
*/
private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =
"CREATE TRIGGER folder_move_notes_on_trash " +
@ -206,10 +225,18 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
" END";
/**
* 构造方法
* @param context 上下文对象
*/
public NotesDatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
/**
* 创建笔记表
* @param db SQLite数据库对象
*/
public void createNoteTable(SQLiteDatabase db) {
db.execSQL(CREATE_NOTE_TABLE_SQL);
reCreateNoteTableTriggers(db);
@ -217,7 +244,12 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
Log.d(TAG, "note table has been created");
}
/**
* 重新创建笔记表相关的触发器
* @param db SQLite数据库对象
*/
private void reCreateNoteTableTriggers(SQLiteDatabase db) {
// 先删除可能存在的旧触发器
db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update");
db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_update");
db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_delete");
@ -226,6 +258,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
db.execSQL("DROP TRIGGER IF EXISTS folder_delete_notes_on_delete");
db.execSQL("DROP TRIGGER IF EXISTS folder_move_notes_on_trash");
// 创建新的触发器
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);
@ -235,41 +268,41 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);
}
/**
* 创建系统文件夹
* @param db SQLite数据库对象
*/
private void createSystemFolder(SQLiteDatabase db) {
ContentValues values = new ContentValues();
/**
* call record foler for call notes
*/
// 创建通话记录文件夹
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
*/
// 创建根文件夹
values.clear();
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
*/
// 创建临时文件夹
values.clear();
values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
/**
* create trash folder
*/
// 创建回收站文件夹
values.clear();
values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
}
/**
* 创建数据表
* @param db SQLite数据库对象
*/
public void createDataTable(SQLiteDatabase db) {
db.execSQL(CREATE_DATA_TABLE_SQL);
reCreateDataTableTriggers(db);
@ -277,16 +310,27 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
Log.d(TAG, "data table has been created");
}
/**
* 重新创建数据表相关的触发器
* @param db SQLite数据库对象
*/
private void reCreateDataTableTriggers(SQLiteDatabase db) {
// 先删除可能存在的旧触发器
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");
// 创建新的触发器
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);
}
/**
* 获取单例实例
* @param context 上下文对象
* @return NotesDatabaseHelper实例
*/
static synchronized NotesDatabaseHelper getInstance(Context context) {
if (mInstance == null) {
mInstance = new NotesDatabaseHelper(context);
@ -296,6 +340,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
@Override
public void onCreate(SQLiteDatabase db) {
// 创建数据库时调用，创建笔记表和数据表
createNoteTable(db);
createDataTable(db);
}
@ -305,34 +350,43 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
boolean reCreateTriggers = false;
boolean skipV2 = false;
// 从版本1升级到版本2
if (oldVersion == 1) {
upgradeToV2(db);
skipV2 = true; // this upgrade including the upgrade from v2 to v3
skipV2 = true; // 这个升级包含从v2到v3的升级
oldVersion++;
}
// 从版本2升级到版本3
if (oldVersion == 2 && !skipV2) {
upgradeToV3(db);
reCreateTriggers = true;
oldVersion++;
}
// 从版本3升级到版本4
if (oldVersion == 3) {
upgradeToV4(db);
oldVersion++;
}
// 如果需要，重新创建触发器
if (reCreateTriggers) {
reCreateNoteTableTriggers(db);
reCreateDataTableTriggers(db);
}
// 检查版本升级是否完成
if (oldVersion != newVersion) {
throw new IllegalStateException("Upgrade notes database to version " + newVersion
+ "fails");
}
}
/**
* 升级到版本2：重建所有表
* @param db SQLite数据库对象
*/
private void upgradeToV2(SQLiteDatabase db) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE);
db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA);
@ -340,23 +394,36 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
createDataTable(db);
}
/**
* 升级到版本3：
* 1. 删除不再使用的触发器
* 2. 添加gtask_id列
* 3. 添加回收站系统文件夹
* @param db SQLite数据库对象
*/
private void upgradeToV3(SQLiteDatabase db) {
// drop unused triggers
// 删除不再使用的触发器
db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_insert");
db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_delete");
db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_update");
// add a column for gtask id
// 添加gtask_id列
db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.GTASK_ID
+ " TEXT NOT NULL DEFAULT ''");
// add a trash system folder
// 添加回收站系统文件夹
ContentValues values = new ContentValues();
values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values);
}
/**
* 升级到版本4：添加version列
* @param db SQLite数据库对象
*/
private void upgradeToV4(SQLiteDatabase db) {
db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
+ " INTEGER NOT NULL DEFAULT 0");
}
}
}
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