xiaomibianqian/NotesDatabaseHelper.java

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.util.Log;

import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.DataConstants;
import net.micode.notes.data.Notes.NoteColumns;

public class NotesDatabaseHelper extends SQLiteOpenHelper {
    private static final String DB_NAME = "note.db"; // 数据库名称

    private static final int DB_VERSION = 4; // 数据库版本号

    public interface TABLE {
        public static final String NOTE = "note"; // 笔记表的名称

        public static final String DATA = "data"; // 数据表的名称
    }

    private static final String TAG = "NotesDatabaseHelper"; // 日志标签

    private static NotesDatabaseHelper mInstance; // 单例实例

    // 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," + // 笔记ID，主键
            NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + // 父级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," + // 笔记计数
            NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," + // 笔记摘要
            NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," + // 笔记类型
            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," + // 本地修改标志
            NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + // 原始父级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," + // 数据ID，主键
            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
            DataColumns.DATA2 + " INTEGER," + // 数据字段2
            DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," + // 数据字段3
            DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," + // 数据字段4
            DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" + // 数据字段5
        ")";

    // 创建数据表的NOTE_ID索引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 + ");"; // 为NOTE_ID创建索引

    /**
     * 在将笔记移动到文件夹时增加文件夹的笔记计数
     */
    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
        "CREATE TRIGGER increase_folder_count_on_update "+
        " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
        "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
        " END";

    /**
     * 当笔记从文件夹中移动时减少文件夹的笔记计数
     */
    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
        "CREATE TRIGGER decrease_folder_count_on_update " +
        " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
        "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
        "  AND " + NoteColumns.NOTES_COUNT + ">0" + ";" +
        " END";

    /**
     * 在向文件夹中插入新笔记时增加文件夹的笔记计数
     */
    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
        "CREATE TRIGGER increase_folder_count_on_insert " +
        " AFTER INSERT ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
        "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
        " END";

    /**
     * 从文件夹中删除笔记时减少文件夹的笔记计数
     */
    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
        "CREATE TRIGGER decrease_folder_count_on_delete " +
        " AFTER DELETE ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
        "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
        "  AND " + NoteColumns.NOTES_COUNT + ">0;" +
        " END";

    /**
     * 在插入类型为 {@link DataConstants#NOTE} 的数据时更新笔记内容
     */
    private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
        "CREATE TRIGGER update_note_content_on_insert " +
        " AFTER INSERT ON " + TABLE.DATA +
        " WHEN new." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
        "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
        " END";

    /**
     * 当类型为 {@link DataConstants#NOTE} 的数据发生更改时更新笔记内容
     */
    private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
        "CREATE TRIGGER update_note_content_on_update " +
        " AFTER UPDATE ON " + TABLE.DATA +
        " WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
        "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
        " END";

    /**
     * 当类型为 {@link DataConstants#NOTE} 的数据被删除时更新笔记内容
     */
private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
        "CREATE TRIGGER update_note_content_on_delete " +
        " AFTER delete ON " + TABLE.DATA + // 当数据表中有数据被删除后触发
        " WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" + // 仅当删除的数据类型为NOTE时触发
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE + // 更新笔记表
        "   SET " + NoteColumns.SNIPPET + "=''" + // 将笔记摘要设置为空
        "  WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" + // 根据被删除数据的NOTE_ID查找对应笔记
        " END";

    /**
     * 删除与已删除笔记关联的数据
     */
    private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
        "CREATE TRIGGER delete_data_on_delete " +
        " AFTER DELETE ON " + TABLE.NOTE + // 当笔记表中的数据被删除后触发
        " BEGIN" +
        "  DELETE FROM " + TABLE.DATA + // 从数据表中删除关联的数据
        "   WHERE " + DataColumns.NOTE_ID + "=old." + NoteColumns.ID + ";" + // 根据已删除笔记的ID进行删除
        " END";

    /**
     * 删除与已删除文件夹关联的笔记
     */
    private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
        "CREATE TRIGGER folder_delete_notes_on_delete " +
        " AFTER DELETE ON " + TABLE.NOTE + // 当笔记表中的数据被删除后触发
        " BEGIN" +
        "  DELETE FROM " + TABLE.NOTE + // 从笔记表中删除关联的笔记
        "   WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" + // 根据已删除文件夹的ID进行删除
        " END";

    /**
     * 将属于已移至垃圾箱文件夹的笔记移动到垃圾箱
     */
    private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =
        "CREATE TRIGGER folder_move_notes_on_trash " +
        " AFTER UPDATE ON " + TABLE.NOTE + // 当笔记表中的数据更新后触发
        " WHEN new." + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER + // 当新父级ID为垃圾箱ID时触发
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE + // 更新笔记表
        "   SET " + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER + // 将父级ID设置为垃圾箱ID
        "  WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" + // 更新与已移除的文件夹ID相关的笔记
        " END";

    // NotesDatabaseHelper构造函数，初始化数据库帮助器
    public NotesDatabaseHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION); // 调用父类构造函数，设置数据库名称和版本
    }

    // 创建笔记表的方法
    public void createNoteTable(SQLiteDatabase db) {
        db.execSQL(CREATE_NOTE_TABLE_SQL); // 执行创建笔记表的SQL语句
        reCreateNoteTableTriggers(db); // 重新创建与笔记表相关的触发器
        createSystemFolder(db); // 创建系统文件夹
        Log.d(TAG, "note table has been created"); // 打印日志，指示笔记表已创建
    }
private void reCreateNoteTableTriggers(SQLiteDatabase db) {
    // 删除已存在的触发器，防止重复创建
    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");
    db.execSQL("DROP TRIGGER IF EXISTS delete_data_on_delete");
    db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_insert");
    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);
    db.execSQL(NOTE_DELETE_DATA_ON_DELETE_TRIGGER);
    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);
}
private void createSystemFolder(SQLiteDatabase db) {
    ContentValues values = new ContentValues();

    /**
     * call record folder for call notes
     */
    values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
    values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
    db.insert(TABLE.NOTE, null, values); // 插入通话记录文件夹

    /**
     * root folder which is default folder
     */
    values.clear(); // 清空之前的内容
    values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
    values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
    db.insert(TABLE.NOTE, null, values); // 插入根文件夹

    /**
     * temporary folder which is used for moving note
     */
    values.clear();
    values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
    values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
    db.insert(TABLE.NOTE, null, values); // 插入临时文件夹

    /**
     * create trash folder
     */
    values.clear();
    values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
    values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
    db.insert(TABLE.NOTE, null, values); // 插入垃圾箱文件夹
}
public void createDataTable(SQLiteDatabase db) {
    db.execSQL(CREATE_DATA_TABLE_SQL); // 执行创建数据表的SQL语句
    reCreateDataTableTriggers(db); // 重新创建与数据表相关的触发器
    db.execSQL(CREATE_DATA_NOTE_ID_INDEX_SQL); // 创建数据表中NOTE_ID的索引
    Log.d(TAG, "data table has been created"); // 打印日志，指示数据表已创建
}
private void reCreateDataTableTriggers(SQLiteDatabase db) {
    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);
}
static synchronized NotesDatabaseHelper getInstance(Context context) {
    if (mInstance == null) {
        mInstance = new NotesDatabaseHelper(context); // 如果实例不存在，则创建新实例
    }
    return mInstance; // 返回单例实例
}
@Override
public void onCreate(SQLiteDatabase db) {
    createNoteTable(db); // 创建笔记表
    createDataTable(db); // 创建数据表
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    boolean reCreateTriggers = false; // 标记是否需要重新创建触发器
    boolean skipV2 = false; // 标记是否跳过v2升级

    if (oldVersion == 1) {
        upgradeToV2(db); // 升级到版本2
        skipV2 = true; // 设置为跳过v2的标记
        oldVersion++;
    }

    if (oldVersion == 2 && !skipV2) {
        upgradeToV3(db); // 升级到版本3
        reCreateTriggers = true; // 设置为需要重新创建触发器
        oldVersion++;
    }

    if (oldVersion == 3) {
        upgradeToV4(db); // 升级到版本4
        oldVersion++;
    }

    if (reCreateTriggers) {
        reCreateNoteTableTriggers(db); // 重新创建与笔记表相关的触发器
        reCreateDataTableTriggers(db); // 重新创建与数据表相关的触发器
    }

    // 如果旧版本不等于新版本，抛出异常
    if (oldVersion != newVersion) {
        throw new IllegalStateException("Upgrade notes database to version " + newVersion + " fails");
    }
}
private void upgradeToV2(SQLiteDatabase db) {
    db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE); // 删除笔记表
    db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA); // 删除数据表
    createNoteTable(db); // 重新创建笔记表
    createDataTable(db); // 重新创建数据表
}
private void upgradeToV3(SQLiteDatabase db) {
    // drop unused triggers
    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
    db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''");

    // add a trash system folder
    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); // 插入垃圾箱文件夹
}
private void upgradeToV4(SQLiteDatabase db) {
    db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0");
}