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庞浩的注释

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pull/13/head
庞浩 3 years ago
parent f5b025db80
commit ced305cd3b
2 changed files with 190 additions and 110 deletions
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app/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java
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@ -26,7 +26,13 @@ import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.DataConstants; import net.micode.notes.data.Notes.DataConstants;
import net.micode.notes.data.Notes.NoteColumns; import net.micode.notes.data.Notes.NoteColumns;
/**
* 这段代码定义了一个名为NotesDatabaseHelper的类，继承自SQLiteOpenHelper。
* 在该类中定义了数据库名（DB_NAME）和数据库版本号（DB_VERSION），
* 并定义了一个内部接口TABLE，该接口中定义了NOTE和DATA两个常量，分别表示数据库中的两个表名。
* 其中SQLiteOpenHelper是Android提供的用于管理SQLite数据库的类，
* 它提供了创建、更新、打开和关闭数据库的方法，同时它也能够在不同的版本之间管理数据库的迁移。
*/
public class NotesDatabaseHelper extends SQLiteOpenHelper { public class NotesDatabaseHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "note.db"; private static final String DB_NAME = "note.db";
@ -38,52 +44,64 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
public static final String DATA = "data"; public static final String DATA = "data";
} }
private static final String TAG = "NotesDatabaseHelper"; private static final String TAG = "NotesDatabaseHelper";//这一行代码定义了一个名为TAG的字符串常量，用于在调试时作为日志标签。
/**
* 定义了一个静态变量mInstance，类型是NotesDatabaseHelper，并且标记为static，
* 表示这个变量是属于类的而不是实例的。
* 在类被加载的时候，这个变量会被创建。这个变量的作用是在整个应用中只创建一个NotesDatabaseHelper实例，
* 这样可以避免在多个地方重复创建数据库连接和实例，提高应用的性能和效率。
*/
private static NotesDatabaseHelper mInstance; private static NotesDatabaseHelper mInstance;
/**
* 这段代码定义了两个字符串常量 CREATE_NOTE_TABLE_SQL 和 CREATE_DATA_TABLE_SQL，
* 分别用于创建两个数据库表格：note 和 data。
*/
private static final String CREATE_NOTE_TABLE_SQL = private static final String CREATE_NOTE_TABLE_SQL =
"CREATE TABLE " + TABLE.NOTE + "(" + "CREATE TABLE " + TABLE.NOTE + "(" +
NoteColumns.ID + " INTEGER PRIMARY KEY," + NoteColumns.ID + " INTEGER PRIMARY KEY," +//笔记 ID，整数类型，作为主键
NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +//父笔记 ID，整数类型，不为空，默认为 0
NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +//提醒时间，整数类型，不为空，默认为 0
NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +//背景颜色 ID，整数类型，不为空，默认为 0
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +//创建时间，整数类型，不为空，默认为当前时间
NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," +//是否有附件，整数类型，不为空，默认为 0
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +//修改时间，整数类型，不为空，默认为当前时间
NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," +//笔记数量，整数类型，不为空，默认为 0
NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," + NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +//笔记概要，文本类型，不为空，默认为空字符串
NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," +//笔记类型，整数类型，不为空，默认为 0
NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," +//小部件 ID，整数类型，不为空，默认为 0
NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," + NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," +//小部件类型，整数类型，不为空，默认为 -1
NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," +//同步 ID，整数类型，不为空，默认为 0
NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," +//本地修改标识，整数类型，不为空，默认为 0
NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +//原始父笔记 ID，整数类型，不为空，默认为 0
NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," + NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +//Google 任务 ID，文本类型，不为空，默认为空字符串
NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" + NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +//版本号，整数类型，不为空，默认为 0
")"; ")";
private static final String CREATE_DATA_TABLE_SQL = private static final String CREATE_DATA_TABLE_SQL =
"CREATE TABLE " + TABLE.DATA + "(" + "CREATE TABLE " + TABLE.DATA + "(" +
DataColumns.ID + " INTEGER PRIMARY KEY," + DataColumns.ID + " INTEGER PRIMARY KEY," +//数据 ID，整数类型，作为主键
DataColumns.MIME_TYPE + " TEXT NOT NULL," + DataColumns.MIME_TYPE + " TEXT NOT NULL," +//MIME 类型，文本类型，不为空
DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," + DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," +//笔记 ID，整数类型，不为空，默认为 0
NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +//创建时间，整数类型，不为空，默认为当前时间
NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +//修改时间，整数类型，不为空，默认为当前时间
DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," + DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," +//数据内容，文本类型，不为空，默认为空字符串
DataColumns.DATA1 + " INTEGER," + DataColumns.DATA1 + " INTEGER," +
DataColumns.DATA2 + " INTEGER," + DataColumns.DATA2 + " INTEGER," +
DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," + DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," + DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +
DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" + DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
")"; ")";
/**
* 这是一个用于创建数据库索引的SQL语句，它将创建一个名为"note_id_index"的索引，
* 该索引将位于"TABLE.DATA"表上，并将使用"DataColumns.NOTE_ID"列作为索引键。
* 这个索引的目的是在查询该表时提高性能，尤其是在根据笔记ID进行过滤时。如果索引已经存在，则不会重复创建。
*/
private static final String CREATE_DATA_NOTE_ID_INDEX_SQL = private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
"CREATE INDEX IF NOT EXISTS note_id_index ON " + "CREATE INDEX IF NOT EXISTS note_id_index ON " +
TABLE.DATA + "(" + DataColumns.NOTE_ID + ");"; TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";
//以下是各种 SQLite 数据库的触发器，用于更新数据库
/** /**
* Increase folder's note count when move note to the folder * Increase folder's note count when move note to the folder（移动笔记到文件夹时增加文件夹的笔记数）
*/ */
private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER = private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER increase_folder_count_on_update "+ "CREATE TRIGGER increase_folder_count_on_update "+
@ -95,7 +113,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Decrease folder's note count when move note from folder * Decrease folder's note count when move note from folder（从文件夹中移动笔记时减少文件夹笔记数）
*/ */
private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER = private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER decrease_folder_count_on_update " + "CREATE TRIGGER decrease_folder_count_on_update " +
@ -108,7 +126,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Increase folder's note count when insert new note to the folder * Increase folder's note count when insert new note to the folder（向文件夹插入新笔记时增加文件夹笔记计数）
*/ */
private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER = private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
"CREATE TRIGGER increase_folder_count_on_insert " + "CREATE TRIGGER increase_folder_count_on_insert " +
@ -120,7 +138,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Decrease folder's note count when delete note from the folder * Decrease folder's note count when delete note from the folder（从文件夹中删除笔记时减少文件夹的笔记数）
*/ */
private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER = private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
"CREATE TRIGGER decrease_folder_count_on_delete " + "CREATE TRIGGER decrease_folder_count_on_delete " +
@ -133,7 +151,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Update note's content when insert data with type {@link DataConstants#NOTE} * Update note's content when insert data with type {@link DataConstants#NOTE}（插入DataConstants类型的数据时更新笔记的内容）
*/ */
private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER = private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
"CREATE TRIGGER update_note_content_on_insert " + "CREATE TRIGGER update_note_content_on_insert " +
@ -146,7 +164,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Update note's content when data with {@link DataConstants#NOTE} type has changed * Update note's content when data with {@link DataConstants#NOTE} type has changed（当DataConstants类型的数据发生更改时更新笔记的内容）
*/ */
private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER = private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
"CREATE TRIGGER update_note_content_on_update " + "CREATE TRIGGER update_note_content_on_update " +
@ -159,7 +177,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Update note's content when data with {@link DataConstants#NOTE} type has deleted * Update note's content when data with {@link DataConstants#NOTE} type has deleted（删除DataConstants类型的数据时更新笔记的内容）
*/ */
private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER = private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
"CREATE TRIGGER update_note_content_on_delete " + "CREATE TRIGGER update_note_content_on_delete " +
@ -172,7 +190,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Delete datas belong to note which has been deleted * Delete datas belong to note which has been deleted（删除属于已删除笔记的数据）
*/ */
private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER = private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
"CREATE TRIGGER delete_data_on_delete " + "CREATE TRIGGER delete_data_on_delete " +
@ -183,7 +201,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Delete notes belong to folder which has been deleted * Delete notes belong to folder which has been deleted（删除属于已删除文件夹的笔记）
*/ */
private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER = private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
"CREATE TRIGGER folder_delete_notes_on_delete " + "CREATE TRIGGER folder_delete_notes_on_delete " +
@ -194,7 +212,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" END"; " END";
/** /**
* Move notes belong to folder which has been moved to trash folder * Move notes belong to folder which has been moved to trash folder（当一个文件夹被更新到废纸篓时，将其下所有笔记移动到废纸篓文件夹）
*/ */
private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER = private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =
"CREATE TRIGGER folder_move_notes_on_trash " + "CREATE TRIGGER folder_move_notes_on_trash " +
@ -206,10 +224,23 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
" WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" + " WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
" END"; " END";
/**
* 这段代码是一个构造函数，用于创建一个NotesDatabaseHelper对象。这个对象是用于管理SQLite数据库的帮助类，可以用来创建、升级和管理数据库表格。
* 构造函数有四个参数，分别是：
* Context context：上下文对象，用于访问应用程序的资源和环境。
* String DB_NAME：数据库的名称。
* CursorFactory factory：用于创建游标对象的工厂类，如果为null，则使用默认工厂。
* int DB_VERSION：数据库的版本号，用于管理数据库的升级。
*/
public NotesDatabaseHelper(Context context) { public NotesDatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION); super(context, DB_NAME, null, DB_VERSION);
} }
/**
* 该方法负责在数据库中创建笔记表。
* 它执行SQL语句CREATE_NOTE_TABLE_SQL来创建表，然后调用reCreateNoteTableTriggers方法来重新创建与笔记表关联的触发器。
* 然后，它通过调用createSystemFolder方法创建一个系统文件夹，并使用Log.d方法记录一条消息，以指示笔记表已经创建。
*/
public void createNoteTable(SQLiteDatabase db) { public void createNoteTable(SQLiteDatabase db) {
db.execSQL(CREATE_NOTE_TABLE_SQL); db.execSQL(CREATE_NOTE_TABLE_SQL);
reCreateNoteTableTriggers(db); reCreateNoteTableTriggers(db);
@ -217,6 +248,12 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
Log.d(TAG, "note table has been created"); Log.d(TAG, "note table has been created");
} }
/**
* 该方法用于重新创建笔记表相关的触发器。
* 它首先使用DROP TRIGGER语句删除所有已有的触发器，然后使用CREATE TRIGGER语句重新创建它们。
* 这个方法是为了在升级数据库时使用，以便更新旧版本的触发器。
* @param db
*/
private void reCreateNoteTableTriggers(SQLiteDatabase db) { private void reCreateNoteTableTriggers(SQLiteDatabase db) {
db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update"); 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_update");
@ -235,18 +272,25 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER); db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);
} }
/**
* 此方法在数据库中创建四个系统文件夹：通话记录文件夹、根文件夹、临时文件夹和废纸篓文件夹。
* 该方法创建一个ContentValues对象，并为每个文件夹的ID和TYPE列添加值。
* 然后，该方法使用SQLiteDatabase类的insert（）方法将值插入笔记表中。
* 系统文件夹的ID定义为Notes类中的常量。
* 通话记录文件夹用于通话笔记，根文件夹是默认文件夹，临时文件夹用于移动笔记，废纸篓文件夹是移动已删除笔记的地方。
*/
private void createSystemFolder(SQLiteDatabase db) { private void createSystemFolder(SQLiteDatabase db) {
ContentValues values = new ContentValues(); ContentValues values = new ContentValues();
/** /**
* call record foler for call notes * call record folder for call notes
*/ */
values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER); values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
db.insert(TABLE.NOTE, null, values); db.insert(TABLE.NOTE, null, values);
/** /**
* root folder which is default folder * root folder which is default folder（mo
*/ */
values.clear(); values.clear();
values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER); values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
@ -270,6 +314,14 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
db.insert(TABLE.NOTE, null, values); db.insert(TABLE.NOTE, null, values);
} }
/**
* 此方法在数据库中创建数据表，并设置必要的触发器和索引。
* 它将SQLiteDatabase类的实例作为参数，用于执行SQL语句以创建数据表、重新创建触发器和创建索引。
* CREATE_DATA_TABLE_SQL常量保存用于创建数据表的SQL语句，该语句定义列及其数据类型。
* 调用recreatedatabletriggers（）方法来删除和重新创建与数据表关联的触发器，这将确保触发器是最新的模式更改。
* CREATE_DATA_NOTE_ID_INDEX_SQL常量保存SQL语句，用于在数据表的NOTE ID列上创建索引，
* 这提高了在NOTE ID列上联接数据和NOTE表的查询的性能。最后，打印一条日志消息，指示数据表已经创建。
*/
public void createDataTable(SQLiteDatabase db) { public void createDataTable(SQLiteDatabase db) {
db.execSQL(CREATE_DATA_TABLE_SQL); db.execSQL(CREATE_DATA_TABLE_SQL);
reCreateDataTableTriggers(db); reCreateDataTableTriggers(db);
@ -277,6 +329,13 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
Log.d(TAG, "data table has been created"); Log.d(TAG, "data table has been created");
} }
/**
* Recreatedatabletriggers方法用于删除用于在insert、update和delete上更新注释内容的现有触发器，
* 然后使用最新定义重新创建它们。
* 以下是被删除的触发器：update_note_content_on_insert_content_on_update_note_content_on_delete，
* 这些是重新创建的触发器：data_update_note_content_on_insert_trigger data_update_trigger data_update_note_content_on_delete_trigger
* 这些触发器确保每当在数据表中创建、更新或删除笔记时，笔记表中的snippet字段都会被更新。
*/
private void reCreateDataTableTriggers(SQLiteDatabase db) { 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_insert");
db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_update"); db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_update");
@ -287,6 +346,12 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER); db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER);
} }
/**
* 这是一个静态方法，它返回NotesDatabaseHelper类的单个实例。
* 它将Context对象作为参数，并检查NotesDatabaseHelper的实例是否为null。
* 如果实例为null，则创建NotesDatabaseHelper类的新实例并返回它。如果实例已经存在，则返回现有实例。
* 该方法是同步的，以确保一次只有一个线程可以访问它，避免任何并发问题。
*/
static synchronized NotesDatabaseHelper getInstance(Context context) { static synchronized NotesDatabaseHelper getInstance(Context context) {
if (mInstance == null) { if (mInstance == null) {
mInstance = new NotesDatabaseHelper(context); mInstance = new NotesDatabaseHelper(context);
@ -294,6 +359,18 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
return mInstance; return mInstance;
} }
/**
* 这是NotesDatabaseHelper类中onCreate（）和onUpgrade（）方法的实现。
* 第一次创建数据库时调用onCreate（）。
* 它分别使用createNoteTable（）和createDataTable（）方法在数据库中创建Note和Data两个表。
* 当数据库需要升级到较新版本时，将调用onUpgrade（）。
* 它首先检查数据库的旧版本，并执行必要的升级将其带到新版本。
* 在这个实现中，有三个升级步骤：从版本1升级到版本2：这将删除现有的Note和数据表，并使用createNoteTable（）和createDataTable（）方法重新创建它们。
* 从版本2升级到版本3：这将删除一些未使用的触发器，并向Note表添加一个新列gtask_id。它还为回收筒创建一个新的系统文件夹。
* 从版本3升级到版本4：这将向注释表添加一个新的列版本。
* 如果在升级步骤中删除了任何触发器，则调用reCreateNoteTableTriggers（）和recreateDatabletriggers（）方法来重新创建它们。
* 如果升级因某种原因失败，将引发IllegalStateException。
*/
@Override @Override
public void onCreate(SQLiteDatabase db) { public void onCreate(SQLiteDatabase db) {
createNoteTable(db); createNoteTable(db);

141
app/src/main/java/net/micode/notes/data/NotesProvider.java
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@ -35,20 +35,20 @@ import net.micode.notes.data.Notes.NoteColumns;
import net.micode.notes.data.NotesDatabaseHelper.TABLE; import net.micode.notes.data.NotesDatabaseHelper.TABLE;
public class NotesProvider extends ContentProvider { public class NotesProvider extends ContentProvider {//定义NotesProvider类，它继承自ContentProvider类
private static final UriMatcher mMatcher; private static final UriMatcher mMatcher;//声明UriMatcher实例
private NotesDatabaseHelper mHelper; private NotesDatabaseHelper mHelper;//声明NotesDatabaseHelper实例用于匹配Uri，以确定请求的类型，例如是否是请求特定的数据项，或者是否是搜索建议请求。
private static final String TAG = "NotesProvider"; private static final String TAG = "NotesProvider";
private static final int URI_NOTE = 1; private static final int URI_NOTE = 1;//代表笔记数据的URI
private static final int URI_NOTE_ITEM = 2; private static final int URI_NOTE_ITEM = 2;//代表单个笔记数据的URI
private static final int URI_DATA = 3; private static final int URI_DATA = 3;//代表附加数据的URI
private static final int URI_DATA_ITEM = 4; private static final int URI_DATA_ITEM = 4;//代表单个附加数据的URI
private static final int URI_SEARCH = 5; private static final int URI_SEARCH = 5;//代表搜索请求的URI
private static final int URI_SEARCH_SUGGEST = 6; private static final int URI_SEARCH_SUGGEST = 6;//代表搜索建议请求的URI
static { static {
mMatcher = new UriMatcher(UriMatcher.NO_MATCH); mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
@ -65,6 +65,7 @@ public class NotesProvider extends ContentProvider {
* x'0A' represents the '\n' character in sqlite. For title and content in the search result, * x'0A' represents the '\n' character in sqlite. For title and content in the search result,
* we will trim '\n' and white space in order to show more information. * we will trim '\n' and white space in order to show more information.
*/ */
// 定义将在搜索结果中返回的列
private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + "," private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
+ NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + "," + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
+ "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + "," + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","
@ -72,15 +73,15 @@ public class NotesProvider extends ContentProvider {
+ R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + "," + R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + ","
+ "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + "," + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
+ "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA; + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
// 定义将执行以检索搜索结果的搜索查询
private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
+ " FROM " + TABLE.NOTE + " FROM " + TABLE.NOTE// 指定要搜索的表
+ " WHERE " + NoteColumns.SNIPPET + " LIKE ?" + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"// 指定搜索查询
+ " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER + " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER// 排除在垃圾桶文件夹中的笔记
+ " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE; + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;// 排除非笔记条目
@Override @Override
public boolean onCreate() { public boolean onCreate() {// 获取数据库帮助类的实例
mHelper = NotesDatabaseHelper.getInstance(getContext()); mHelper = NotesDatabaseHelper.getInstance(getContext());
return true; return true;
} }
@ -88,30 +89,30 @@ public class NotesProvider extends ContentProvider {
@Override @Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
String sortOrder) { String sortOrder) {
Cursor c = null; Cursor c = null;// 获取可读的数据库实例
SQLiteDatabase db = mHelper.getReadableDatabase(); SQLiteDatabase db = mHelper.getReadableDatabase();
String id = null; String id = null;
switch (mMatcher.match(uri)) { switch (mMatcher.match(uri)) {
case URI_NOTE: case URI_NOTE:// 查询所有笔记
c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null, c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
sortOrder); sortOrder);
break; break;
case URI_NOTE_ITEM: case URI_NOTE_ITEM:// 查询单个笔记
id = uri.getPathSegments().get(1); id = uri.getPathSegments().get(1);
c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder); + parseSelection(selection), selectionArgs, null, null, sortOrder);
break; break;
case URI_DATA: case URI_DATA:// 查询所有数据
c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null, c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
sortOrder); sortOrder);
break; break;
case URI_DATA_ITEM: case URI_DATA_ITEM: // 查询单个数据
id = uri.getPathSegments().get(1); id = uri.getPathSegments().get(1);
c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder); + parseSelection(selection), selectionArgs, null, null, sortOrder);
break; break;
case URI_SEARCH: case URI_SEARCH:
case URI_SEARCH_SUGGEST: case URI_SEARCH_SUGGEST:// 搜索笔记
if (sortOrder != null || projection != null) { if (sortOrder != null || projection != null) {
throw new IllegalArgumentException( throw new IllegalArgumentException(
"do not specify sortOrder, selection, selectionArgs, or projection" + "with this query"); "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
@ -130,7 +131,7 @@ public class NotesProvider extends ContentProvider {
return null; return null;
} }
try { try {// 搜索所有匹配的笔记
searchString = String.format("%%%s%%", searchString); searchString = String.format("%%%s%%", searchString);
c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY, c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
new String[] { searchString }); new String[] { searchString });
@ -141,44 +142,44 @@ public class NotesProvider extends ContentProvider {
default: default:
throw new IllegalArgumentException("Unknown URI " + uri); throw new IllegalArgumentException("Unknown URI " + uri);
} }
if (c != null) { if (c != null) {// 设置通知URI，以便在数据更改时通知观察者
c.setNotificationUri(getContext().getContentResolver(), uri); c.setNotificationUri(getContext().getContentResolver(), uri);
} }
return c; return c;
} }
@Override @Override
public Uri insert(Uri uri, ContentValues values) { public Uri insert(Uri uri, ContentValues values) {// 获取可写的 SQLiteDatabase 对象
SQLiteDatabase db = mHelper.getWritableDatabase(); SQLiteDatabase db = mHelper.getWritableDatabase();// 初始化三个变量，用于存储 note、data 和插入的记录的 ID
long dataId = 0, noteId = 0, insertedId = 0; long dataId = 0, noteId = 0, insertedId = 0;// 根据传入的 Uri 进行匹配
switch (mMatcher.match(uri)) { switch (mMatcher.match(uri)) {
case URI_NOTE: case URI_NOTE:// 向 TABLE.NOTE 表中插入记录，并获取插入的记录的 ID
insertedId = noteId = db.insert(TABLE.NOTE, null, values); insertedId = noteId = db.insert(TABLE.NOTE, null, values);
break; break;
case URI_DATA: case URI_DATA:
if (values.containsKey(DataColumns.NOTE_ID)) { if (values.containsKey(DataColumns.NOTE_ID)) {// 如果 ContentValues 包含 DataColumns.NOTE_ID 列
noteId = values.getAsLong(DataColumns.NOTE_ID); noteId = values.getAsLong(DataColumns.NOTE_ID);// 获取 DataColumns.NOTE_ID 列的值
} else { } else {
Log.d(TAG, "Wrong data format without note id:" + values.toString()); Log.d(TAG, "Wrong data format without note id:" + values.toString());
} }//打印日志
insertedId = dataId = db.insert(TABLE.DATA, null, values); insertedId = dataId = db.insert(TABLE.DATA, null, values);// 向 TABLE.DATA 表中插入记录，并获取插入的记录的 ID
break; break;
default: default:
throw new IllegalArgumentException("Unknown URI " + uri); throw new IllegalArgumentException("Unknown URI " + uri);// 抛出 IllegalArgumentException 异常
} }
// Notify the note uri // Notify the note uri
if (noteId > 0) { if (noteId > 0) { // 如果 noteId 大于 0，则通知 content resolver 对应的 Uri 对应的数据已经发生了变化
getContext().getContentResolver().notifyChange( getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null); ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
} }
// Notify the data uri // Notify the data uri
if (dataId > 0) { if (dataId > 0) {// 如果 dataId 大于 0，则通知 content resolver 对应的 Uri 对应的数据已经发生了变化
getContext().getContentResolver().notifyChange( getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null); ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
} }
return ContentUris.withAppendedId(uri, insertedId); return ContentUris.withAppendedId(uri, insertedId); // 返回插入的记录的 Uri
} }
@Override @Override
@ -187,60 +188,62 @@ public class NotesProvider extends ContentProvider {
String id = null; String id = null;
SQLiteDatabase db = mHelper.getWritableDatabase(); SQLiteDatabase db = mHelper.getWritableDatabase();
boolean deleteData = false; boolean deleteData = false;
switch (mMatcher.match(uri)) { switch (mMatcher.match(uri)) {// 根据传入的 Uri 进行匹配
case URI_NOTE: case URI_NOTE:// 如果匹配到 URI_NOTE
selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 "; selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";// 组合 selection 条件，以确保删除的是用户笔记，而不是系统文件夹
count = db.delete(TABLE.NOTE, selection, selectionArgs); count = db.delete(TABLE.NOTE, selection, selectionArgs);// 删除 TABLE.NOTE 表中符合条件的记录，并返回删除的数量
break; break;
case URI_NOTE_ITEM: case URI_NOTE_ITEM: // 如果匹配到 URI_NOTE_ITEM
id = uri.getPathSegments().get(1); id = uri.getPathSegments().get(1);// 获取 Uri 中的 ID
/** /**
* ID that smaller than 0 is system folder which is not allowed to * ID that smaller than 0 is system folder which is not allowed to
* trash * trash
*/ */
long noteId = Long.valueOf(id); long noteId = Long.valueOf(id);
if (noteId <= 0) { if (noteId <= 0) { // 如果 ID 小于等于 0，则直接跳出 switch 语句
break; break;
} }
count = db.delete(TABLE.NOTE, count = db.delete(TABLE.NOTE,
NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs); NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);// 删除 TABLE.NOTE 表中符合条件的记录，并返回删除的数量
break; break;
case URI_DATA: case URI_DATA:// 如果匹配到 URI_DATA
count = db.delete(TABLE.DATA, selection, selectionArgs); count = db.delete(TABLE.DATA, selection, selectionArgs);// 删除 TABLE.DATA 表中符合条件的记录，并返回删除的数量
deleteData = true; deleteData = true;
break; break;
case URI_DATA_ITEM: case URI_DATA_ITEM:// 如果匹配到 URI_DATA_ITEM
id = uri.getPathSegments().get(1); id = uri.getPathSegments().get(1); // 获取 Uri 中的 ID
count = db.delete(TABLE.DATA, count = db.delete(TABLE.DATA,
DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs); DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);// 删除 TABLE.DATA 表中符合条件的记录，并返回删除的数量
deleteData = true; deleteData = true;
break; break;
default: default:// 如果无法匹配到 Uri
throw new IllegalArgumentException("Unknown URI " + uri); throw new IllegalArgumentException("Unknown URI " + uri);// 抛出 IllegalArgumentException 异常
} }
if (count > 0) { if (count > 0) {// 如果删除的数量大于 0
if (deleteData) { if (deleteData) {
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
} } // 如果删除的是 TABLE.DATA 表中的记录，则通知 content resolver 对应的 Uri 对应的笔记数据已经发生了变化
getContext().getContentResolver().notifyChange(uri, null); getContext().getContentResolver().notifyChange(uri, null);
} }
return count; return count;// 返回删除的数量
} }
@Override @Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
int count = 0; int count = 0;// 受影响的行数
String id = null; String id = null;// 被更新的笔记或数据项的ID
SQLiteDatabase db = mHelper.getWritableDatabase(); SQLiteDatabase db = mHelper.getWritableDatabase();// 获取可写数据库
boolean updateData = false; boolean updateData = false;// 是否更新数据项
switch (mMatcher.match(uri)) {
switch (mMatcher.match(uri)) {// 使用 switch 语句处理不同类型的 URI
case URI_NOTE: case URI_NOTE:
increaseNoteVersion(-1, selection, selectionArgs); increaseNoteVersion(-1, selection, selectionArgs);// 在更新前增加所有受影响的笔记的版本号
count = db.update(TABLE.NOTE, values, selection, selectionArgs); count = db.update(TABLE.NOTE, values, selection, selectionArgs);// 更新数据库中的行并获取受影响的行数
break; break;
case URI_NOTE_ITEM: case URI_NOTE_ITEM:
id = uri.getPathSegments().get(1); id = uri.getPathSegments().get(1);// 在更新前增加笔记的版本号
increaseNoteVersion(Long.valueOf(id), selection, selectionArgs); increaseNoteVersion(Long.valueOf(id), selection, selectionArgs); // 更新数据库中的行并获取受影响的行数
count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs); + parseSelection(selection), selectionArgs);
break; break;
@ -257,20 +260,20 @@ public class NotesProvider extends ContentProvider {
default: default:
throw new IllegalArgumentException("Unknown URI " + uri); throw new IllegalArgumentException("Unknown URI " + uri);
} }
// 如果有行被更新，通知已注册的 ContentObserver
if (count > 0) { if (count > 0) {
if (updateData) { if (updateData) {
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
} }
getContext().getContentResolver().notifyChange(uri, null); getContext().getContentResolver().notifyChange(uri, null);
} }
return count; return count; // 返回受影响的行数
} }
// 辅助方法，如果传递了 selection 参数，则将其添加到 SQL 查询中
private String parseSelection(String selection) { private String parseSelection(String selection) {
return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""); return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
} }
// 辅助方法，在更新笔记之前增加其版本号
private void increaseNoteVersion(long id, String selection, String[] selectionArgs) { private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
StringBuilder sql = new StringBuilder(120); StringBuilder sql = new StringBuilder(120);
sql.append("UPDATE "); sql.append("UPDATE ");
@ -278,7 +281,7 @@ public class NotesProvider extends ContentProvider {
sql.append(" SET "); sql.append(" SET ");
sql.append(NoteColumns.VERSION); sql.append(NoteColumns.VERSION);
sql.append("=" + NoteColumns.VERSION + "+1 "); sql.append("=" + NoteColumns.VERSION + "+1 ");
// 如果传递了 ID 或 selection 参数，则将其添加到 SQL 查询中
if (id > 0 || !TextUtils.isEmpty(selection)) { if (id > 0 || !TextUtils.isEmpty(selection)) {
sql.append(" WHERE "); sql.append(" WHERE ");
} }
@ -293,12 +296,12 @@ public class NotesProvider extends ContentProvider {
sql.append(selectString); sql.append(selectString);
} }
mHelper.getWritableDatabase().execSQL(sql.toString()); mHelper.getWritableDatabase().execSQL(sql.toString());// 执行 SQL 查询以更新笔记的版本号
} }
@Override @Override
public String getType(Uri uri) { public String getType(Uri uri) {
// TODO Auto-generated method stub // TODO Auto-generated method stub这是一个待办事项，需要根据 ContentProvider需求添加适当的 MIME类型。
return null; return null;
} }

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