From 16c1a52349b583d3f6d4c9214a5da8aa420a3eff Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E5=A4=8F=E5=BD=A6=E5=8D=9A?= <1139346339@qq.com> Date: Sun, 19 Nov 2023 10:19:26 +0800 Subject: [PATCH] =?UTF-8?q?=E6=96=B0=E6=89=B9=E6=B3=A8=E4=BA=86=E5=8F=A6?= =?UTF-8?q?=E5=A4=96=E4=B8=A4=E4=B8=AA=20data=E6=96=87=E4=BB=B6=E5=A4=B9?= =?UTF-8?q?=E5=B7=B2=E6=89=B9=E6=B3=A8=E5=AE=8C?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../notes/data/NotesDatabaseHelper.java | 20 +++++++++---------- .../net/micode/notes/data/NotesProvider.java | 13 ++++++------ 2 files changed, 17 insertions(+), 16 deletions(-) diff --git a/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java b/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java index ffe5d57..042c2d9 100644 --- a/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java +++ b/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java @@ -27,7 +27,7 @@ import net.micode.notes.data.Notes.DataConstants; import net.micode.notes.data.Notes.NoteColumns; -public class NotesDatabaseHelper extends SQLiteOpenHelper { +public class NotesDatabaseHelper extends SQLiteOpenHelper { //定义数据库相关的名称以及标签 private static final String DB_NAME = "note.db"; private static final int DB_VERSION = 4; @@ -42,7 +42,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { private static NotesDatabaseHelper mInstance; - private static final String CREATE_NOTE_TABLE_SQL = + private static final String CREATE_NOTE_TABLE_SQL =//规范定义数据库存储信息的格式以及组成部分 "CREATE TABLE " + TABLE.NOTE + "(" + NoteColumns.ID + " INTEGER PRIMARY KEY," + NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + @@ -85,7 +85,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { /** * Increase folder's note count when move note to the folder */ - private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER = + private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =//设置触发器，在笔记集更新的时候增加数量1 "CREATE TRIGGER increase_folder_count_on_update "+ " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE + " BEGIN " + @@ -97,7 +97,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { /** * Decrease folder's note count when move note from folder */ - private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER = + private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =//类似的设置触发器，在笔记集更新的时候减少数量1 "CREATE TRIGGER decrease_folder_count_on_update " + " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE + " BEGIN " + @@ -110,7 +110,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { /** * Increase folder's note count when insert new note to the folder */ - private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER = + private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =//设置触发器，在笔记集创建的时候增加数量1 "CREATE TRIGGER increase_folder_count_on_insert " + " AFTER INSERT ON " + TABLE.NOTE + " BEGIN " + @@ -122,7 +122,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { /** * Decrease folder's note count when delete note from the folder */ - private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER = + private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =//设置触发器，在笔记集删除文件的时候-1 "CREATE TRIGGER decrease_folder_count_on_delete " + " AFTER DELETE ON " + TABLE.NOTE + " BEGIN " + @@ -135,7 +135,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { /** * Update note's content when insert data with type {@link DataConstants#NOTE} */ - private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER = + private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =//设置触发器用于在笔记中数据更改时进行相应ID，字段等的更新 "CREATE TRIGGER update_note_content_on_insert " + " AFTER INSERT ON " + TABLE.DATA + " WHEN new." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" + @@ -210,14 +210,14 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { super(context, DB_NAME, null, DB_VERSION); } - public void createNoteTable(SQLiteDatabase db) { + public void createNoteTable(SQLiteDatabase db) {//创建并管理日志信息表 db.execSQL(CREATE_NOTE_TABLE_SQL); reCreateNoteTableTriggers(db); createSystemFolder(db); Log.d(TAG, "note table has been created"); } - private void reCreateNoteTableTriggers(SQLiteDatabase db) { + private void reCreateNoteTableTriggers(SQLiteDatabase db) {//重置触发器 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"); @@ -301,7 +301,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper { } @Override - public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { + public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {//用于检查并进行数据库版本的更新，保障版本控制 boolean reCreateTriggers = false; boolean skipV2 = false; diff --git a/src/main/java/net/micode/notes/data/NotesProvider.java b/src/main/java/net/micode/notes/data/NotesProvider.java index edb0a60..b29c6fd 100644 --- a/src/main/java/net/micode/notes/data/NotesProvider.java +++ b/src/main/java/net/micode/notes/data/NotesProvider.java @@ -35,7 +35,7 @@ import net.micode.notes.data.Notes.NoteColumns; import net.micode.notes.data.NotesDatabaseHelper.TABLE; -public class NotesProvider extends ContentProvider { +public class NotesProvider extends ContentProvider {//定义URL以及匹配规则 private static final UriMatcher mMatcher; private NotesDatabaseHelper mHelper; @@ -86,12 +86,12 @@ public class NotesProvider extends ContentProvider { } @Override - public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, + public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,//执行数据库查询操作 String sortOrder) { Cursor c = null; SQLiteDatabase db = mHelper.getReadableDatabase(); String id = null; - switch (mMatcher.match(uri)) { + switch (mMatcher.match(uri)) {//匹配数据库查询关键字 case URI_NOTE: c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null, sortOrder); @@ -148,7 +148,7 @@ public class NotesProvider extends ContentProvider { } @Override - public Uri insert(Uri uri, ContentValues values) { + public Uri insert(Uri uri, ContentValues values) {//insert向数据库中插入一条数据信息值 SQLiteDatabase db = mHelper.getWritableDatabase(); long dataId = 0, noteId = 0, insertedId = 0; switch (mMatcher.match(uri)) { @@ -182,7 +182,8 @@ public class NotesProvider extends ContentProvider { } @Override - public int delete(Uri uri, String selection, String[] selectionArgs) { + public int delete(Uri uri, String selection, String[] selectionArgs) {//实现删除操作 + /*这两个参数通常在一起使用，以定义一个特定的删除操作。selection 定义了哪些数据应该被删除，而 selectionArgs 为 selection 中的占位符提供了具体的值。*/ int count = 0; String id = null; SQLiteDatabase db = mHelper.getWritableDatabase(); @@ -228,7 +229,7 @@ public class NotesProvider extends ContentProvider { } @Override - public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { + public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {//更新 int count = 0; String id = null; SQLiteDatabase db = mHelper.getWritableDatabase();