diff --git a/src/net/micode/notes/data/NotesProvider.java b/src/net/micode/notes/data/NotesProvider.java index edb0a60..ec80b4f 100644 --- a/src/net/micode/notes/data/NotesProvider.java +++ b/src/net/micode/notes/data/NotesProvider.java @@ -14,8 +14,9 @@ * limitations under the License. */ -package net.micode.notes.data; + //这段代码是笔记应用的核心数据访问层，封装了所有数据库操作，并通过标准ContentProvider接口对外提供服务，同时实现了搜索功能集成。 +package net.micode.notes.data;//导入包 import android.app.SearchManager; import android.content.ContentProvider; @@ -34,24 +35,31 @@ import net.micode.notes.data.Notes.DataColumns; import net.micode.notes.data.Notes.NoteColumns; import net.micode.notes.data.NotesDatabaseHelper.TABLE; - +/** + * 笔记应用的内容提供者，负责管理笔记数据的CRUD操作和搜索功能 + */ public class NotesProvider extends ContentProvider { + // URI匹配器，用于匹配不同的URI请求 private static final UriMatcher mMatcher; + // 数据库帮助类实例 private NotesDatabaseHelper mHelper; + // 日志标签 private static final String TAG = "NotesProvider"; - private static final int URI_NOTE = 1; - private static final int URI_NOTE_ITEM = 2; - private static final int URI_DATA = 3; - private static final int URI_DATA_ITEM = 4; - - private static final int URI_SEARCH = 5; - private static final int URI_SEARCH_SUGGEST = 6; + // URI匹配代码常量 + private static final int URI_NOTE = 1; // 笔记集合操作 + private static final int URI_NOTE_ITEM = 2; // 单条笔记操作 + private static final int URI_DATA = 3; // 数据集合操作 + private static final int URI_DATA_ITEM = 4; // 单条数据操作 + private static final int URI_SEARCH = 5; // 搜索操作 + private static final int URI_SEARCH_SUGGEST = 6; // 搜索建议操作 + // 静态初始化块，配置URI匹配器 static { mMatcher = new UriMatcher(UriMatcher.NO_MATCH); + // 添加URI匹配规则 mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE); mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM); mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA); @@ -62,8 +70,9 @@ public class NotesProvider extends ContentProvider { } /** - * 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. + * 搜索结果的投影(列)定义 + * x'0A'代表SQLite中的换行符'\n'。对于搜索结果中的标题和内容， + * 我们将修剪'\n'和空格以显示更多信息。 */ private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + "," + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + "," @@ -73,6 +82,7 @@ public class NotesProvider extends ContentProvider { + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + "," + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA; + // 笔记片段搜索查询SQL private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION + " FROM " + TABLE.NOTE + " WHERE " + NoteColumns.SNIPPET + " LIKE ?" @@ -81,6 +91,7 @@ public class NotesProvider extends ContentProvider { @Override public boolean onCreate() { + // 初始化数据库帮助类 mHelper = NotesDatabaseHelper.getInstance(getContext()); return true; } @@ -91,27 +102,34 @@ public class NotesProvider extends ContentProvider { Cursor c = null; SQLiteDatabase db = mHelper.getReadableDatabase(); String id = null; + + // 根据URI匹配不同类型的数据请求 switch (mMatcher.match(uri)) { case URI_NOTE: + // 查询笔记表 c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null, sortOrder); break; case URI_NOTE_ITEM: + // 查询单条笔记 id = uri.getPathSegments().get(1); c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs, null, null, sortOrder); break; case URI_DATA: + // 查询数据表 c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null, sortOrder); break; case URI_DATA_ITEM: + // 查询单条数据 id = uri.getPathSegments().get(1); c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs, null, null, sortOrder); break; case URI_SEARCH: case URI_SEARCH_SUGGEST: + // 处理搜索请求 if (sortOrder != null || projection != null) { throw new IllegalArgumentException( "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query"); @@ -131,6 +149,7 @@ public class NotesProvider extends ContentProvider { } try { + // 格式化搜索字符串并执行搜索查询 searchString = String.format("%%%s%%", searchString); c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY, new String[] { searchString }); @@ -141,6 +160,8 @@ public class NotesProvider extends ContentProvider { default: throw new IllegalArgumentException("Unknown URI " + uri); } + + // 设置内容解析器通知URI if (c != null) { c.setNotificationUri(getContext().getContentResolver(), uri); } @@ -151,11 +172,15 @@ public class NotesProvider extends ContentProvider { public Uri insert(Uri uri, ContentValues values) { SQLiteDatabase db = mHelper.getWritableDatabase(); long dataId = 0, noteId = 0, insertedId = 0; + + // 根据URI匹配不同类型的数据插入 switch (mMatcher.match(uri)) { case URI_NOTE: + // 插入笔记 insertedId = noteId = db.insert(TABLE.NOTE, null, values); break; case URI_DATA: + // 插入数据 if (values.containsKey(DataColumns.NOTE_ID)) { noteId = values.getAsLong(DataColumns.NOTE_ID); } else { @@ -166,18 +191,20 @@ public class NotesProvider extends ContentProvider { default: throw new IllegalArgumentException("Unknown URI " + uri); } - // Notify the note uri + + // 通知笔记URI变更 if (noteId > 0) { getContext().getContentResolver().notifyChange( ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null); } - // Notify the data uri + // 通知数据URI变更 if (dataId > 0) { getContext().getContentResolver().notifyChange( ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null); } + // 返回新插入数据的URI return ContentUris.withAppendedId(uri, insertedId); } @@ -187,16 +214,19 @@ public class NotesProvider extends ContentProvider { String id = null; SQLiteDatabase db = mHelper.getWritableDatabase(); boolean deleteData = false; + + // 根据URI匹配不同类型的数据删除 switch (mMatcher.match(uri)) { case URI_NOTE: + // 防止删除系统文件夹 selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 "; count = db.delete(TABLE.NOTE, selection, selectionArgs); break; case URI_NOTE_ITEM: + // 删除单条笔记 id = uri.getPathSegments().get(1); /** - * ID that smaller than 0 is system folder which is not allowed to - * trash + * ID小于0的是系统文件夹，不允许删除 */ long noteId = Long.valueOf(id); if (noteId <= 0) { @@ -206,10 +236,12 @@ public class NotesProvider extends ContentProvider { NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs); break; case URI_DATA: + // 删除数据 count = db.delete(TABLE.DATA, selection, selectionArgs); deleteData = true; break; case URI_DATA_ITEM: + // 删除单条数据 id = uri.getPathSegments().get(1); count = db.delete(TABLE.DATA, DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs); @@ -218,6 +250,8 @@ public class NotesProvider extends ContentProvider { default: throw new IllegalArgumentException("Unknown URI " + uri); } + + // 通知数据变更 if (count > 0) { if (deleteData) { getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); @@ -233,22 +267,28 @@ public class NotesProvider extends ContentProvider { String id = null; SQLiteDatabase db = mHelper.getWritableDatabase(); boolean updateData = false; + + // 根据URI匹配不同类型的数据更新 switch (mMatcher.match(uri)) { case URI_NOTE: + // 更新笔记时增加版本号 increaseNoteVersion(-1, selection, selectionArgs); count = db.update(TABLE.NOTE, values, selection, selectionArgs); break; case URI_NOTE_ITEM: + // 更新单条笔记时增加版本号 id = uri.getPathSegments().get(1); increaseNoteVersion(Long.valueOf(id), selection, selectionArgs); count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs); break; case URI_DATA: + // 更新数据 count = db.update(TABLE.DATA, values, selection, selectionArgs); updateData = true; break; case URI_DATA_ITEM: + // 更新单条数据 id = uri.getPathSegments().get(1); count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs); @@ -258,6 +298,7 @@ public class NotesProvider extends ContentProvider { throw new IllegalArgumentException("Unknown URI " + uri); } + // 通知数据变更 if (count > 0) { if (updateData) { getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); @@ -267,10 +308,21 @@ public class NotesProvider extends ContentProvider { return count; } + /** + * 解析选择条件，添加AND连接符 + * @param selection 原始选择条件 + * @return 格式化后的选择条件 + */ private String parseSelection(String selection) { return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""); } + /** + * 增加笔记版本号 + * @param id 笔记ID，如果为-1则使用selection条件 + * @param selection 选择条件 + * @param selectionArgs 选择参数 + */ private void increaseNoteVersion(long id, String selection, String[] selectionArgs) { StringBuilder sql = new StringBuilder(120); sql.append("UPDATE "); @@ -298,8 +350,7 @@ public class NotesProvider extends ContentProvider { @Override public String getType(Uri uri) { - // TODO Auto-generated method stub + // TODO: 实现获取URI类型的方法 return null; } - }