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/*
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* Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package net.micode.notes.data;
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import android.app.SearchManager;
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import android.content.ContentProvider;
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import android.content.ContentUris;
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import android.content.ContentValues;
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import android.content.Intent;
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import android.content.UriMatcher;
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import android.database.Cursor;
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import android.database.sqlite.SQLiteDatabase;
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import android.net.Uri;
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import android.text.TextUtils;
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import android.util.Log;
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import net.micode.notes.R;
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import net.micode.notes.data.Notes.DataColumns;
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import net.micode.notes.data.Notes.NoteColumns;
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import net.micode.notes.data.NotesDatabaseHelper.TABLE;
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public class NotesProvider extends ContentProvider {
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// UriMatcher用于匹配不同的URI请求，帮助识别是请求笔记还是笔记数据，或是搜索请求等，并返回相应的请求类型代码
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private static final UriMatcher mMatcher;
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// 数据库辅助类，用于创建和管理数据库
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private NotesDatabaseHelper mHelper;
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// 日志标签，便于调试和日志记录
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private static final String TAG = "NotesProvider";
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// 定义URI请求类型常量
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private static final int URI_NOTE = 1; // 匹配所有笔记的URI
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private static final int URI_NOTE_ITEM = 2; // 匹配特定笔记ID的URI
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private static final int URI_DATA = 3; // 匹配所有笔记数据的URI
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private static final int URI_DATA_ITEM = 4; // 匹配特定笔记数据ID的URI
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private static final int URI_SEARCH = 5; // 匹配搜索请求的URI
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private static final int URI_SEARCH_SUGGEST = 6; // 匹配搜索建议请求的URI
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// 静态代码块，在类加载时初始化UriMatcher，添加各种URI模式及其对应的代码
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static {
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mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
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mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
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mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
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mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
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mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
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mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
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mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
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mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
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}
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/**
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* x'0A'表示在sqlite中的'\n'字符。对于搜索结果中的标题和内容，
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* 我们将修剪'\n'和空白字符，以便显示更多信息。
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* 此投影用于搜索结果，将笔记ID和片段内容格式化以便显示。
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*/
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private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
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+ NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
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+ "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","
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+ "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_2 + ","
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+ R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + ","
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+ "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
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+ "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
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// SQL查询语句，用于根据搜索字符串查询笔记片段。查询结果将用于搜索功能和搜索建议。
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private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
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+ " FROM " + TABLE.NOTE
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+ " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
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+ " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER
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+ " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;
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// 创建ContentProvider时调用，初始化NotesDatabaseHelper以准备数据库操作
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@Override
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public boolean onCreate() {
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mHelper = NotesDatabaseHelper.getInstance(getContext()); // 获取数据库帮助器的单例实例
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return true;
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}
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// 根据不同的URI请求类型执行查询操作，返回查询结果的游标
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@Override
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public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
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String sortOrder) {
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Cursor c = null;
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SQLiteDatabase db = mHelper.getReadableDatabase(); // 获取可读的数据库实例
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String id = null;
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switch (mMatcher.match(uri)) {
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case URI_NOTE:
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// 查询所有笔记，返回符合条件的所有笔记游标
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c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null, sortOrder);
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break;
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case URI_NOTE_ITEM:
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// 查询特定ID的笔记，返回符合条件的单条笔记游标
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id = uri.getPathSegments().get(1); // 获取URI路径中的笔记ID
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c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
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+ parseSelection(selection), selectionArgs, null, null, sortOrder);
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break;
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case URI_DATA:
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// 查询所有笔记数据，返回符合条件的所有笔记数据游标
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c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null, sortOrder);
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break;
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case URI_DATA_ITEM:
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// 查询特定ID的笔记数据，返回符合条件的单条笔记数据游标
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id = uri.getPathSegments().get(1); // 获取URI路径中的笔记数据ID
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c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
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+ parseSelection(selection), selectionArgs, null, null, sortOrder);
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break;
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case URI_SEARCH:
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case URI_SEARCH_SUGGEST:
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// 搜索时不允许指定排序条件、选择条件、选择参数或投影，以确保搜索结果的一致性
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if (sortOrder != null || projection != null) {
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throw new IllegalArgumentException(
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"不允许在搜索时指定排序条件、选择条件、选择参数或投影");
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}
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String searchString = null;
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// 获取搜索字符串
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if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
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if (uri.getPathSegments().size() > 1) {
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searchString = uri.getPathSegments().get(1); // 从URI路径中获取搜索字符串
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}
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} else {
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searchString = uri.getQueryParameter("pattern"); // 从URI查询参数中获取搜索字符串
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}
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// 如果搜索字符串为空，返回null
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if (TextUtils.isEmpty(searchString)) {
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return null;
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}
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try {
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// 格式化搜索字符串，使其可以用于LIKE查询。例如，如果搜索字符串是"abc"，则格式化后的字符串是"%abc%"
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searchString = String.format("%%%s%%", searchString);
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// 执行搜索查询，返回搜索结果游标
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c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
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new String[] { searchString });
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} catch (IllegalStateException ex) {
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Log.e(TAG, "发生异常: " + ex.toString()); // 记录异常日志
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}
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break;
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default:
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// 如果URI请求类型未知，抛出异常以提示错误
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throw new IllegalArgumentException("未知的URI " + uri);
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}
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// 设置游标的通知URI，以便内容变化时通知监听者。这有助于UI更新和数据同步。
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if (c != null) {
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c.setNotificationUri(getContext().getContentResolver(), uri);
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}
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return c; // 返回查询结果游标
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}
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// 根据不同的URI请求类型插入数据，返回插入数据的URI
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@Override
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public Uri insert(Uri uri, ContentValues values) {
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SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写的数据库实例
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long dataId = 0, noteId = 0, insertedId = 0;
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switch (mMatcher.match(uri)) {
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case URI_NOTE:
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// 插入新的笔记，返回插入笔记的ID
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insertedId = noteId = db.insert(TABLE.NOTE, null, values);
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break;
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case URI_DATA:
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// 插入新的笔记数据，返回插入数据的ID
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if (values.containsKey(DataColumns.NOTE_ID)) {
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noteId = values.getAsLong(DataColumns.NOTE_ID); // 获取关联的笔记ID
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} else {
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Log.d(TAG, "数据格式错误，缺少笔记ID:" + values.toString()); // 记录日志，表示数据格式错误
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}
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insertedId = dataId = db.insert(TABLE.DATA, null, values);
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break;
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default:
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// 如果URI请求类型未知，抛出异常以提示错误
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throw new IllegalArgumentException("未知的URI " + uri);
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}
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// 通知笔记URI变化，以便UI更新和数据同步
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if (noteId > 0) {
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getContext().getContentResolver().notifyChange(
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ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
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}
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// 通知数据URI变化，以便UI更新和数据同步
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if (dataId > 0) {
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getContext().getContentResolver().notifyChange(
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ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
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}
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return ContentUris.withAppendedId(uri, insertedId); // 返回插入数据的URI
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}
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// 根据不同的URI请求类型删除数据，返回删除的数据条目数
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@Override
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public int delete(Uri uri, String selection, String[] selectionArgs) {
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int count = 0;
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String id = null;
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SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写的数据库实例
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boolean deleteData = false;
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switch (mMatcher.match(uri)) {
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case URI_NOTE:
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// 删除笔记时，确保ID大于0，以防止删除系统文件夹
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selection = " AND (" + selection + ") AND " + NoteColumns.ID + ">0 ";
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count = db.delete(TABLE.NOTE, selection, selectionArgs);
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break;
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case URI_NOTE_ITEM:
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id = uri.getPathSegments().get(1); // 获取URI路径中的笔记ID
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long noteId = Long.valueOf(id);
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// ID小于等于0的笔记为系统文件夹，不允许删除
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if (noteId <= 0) {
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break;
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}
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// 删除特定ID的笔记
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count = db.delete(TABLE.NOTE,
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NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
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break;
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case URI_DATA:
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// 删除笔记数据
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count = db.delete(TABLE.DATA, selection, selectionArgs);
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deleteData = true;
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break;
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case URI_DATA_ITEM:
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id = uri.getPathSegments().get(1); // 获取URI路径中的笔记数据ID
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// 删除特定ID的笔记数据
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count = db.delete(TABLE.DATA,
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DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
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deleteData = true;
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break;
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default:
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// 如果URI请求类型未知，抛出异常以提示错误
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throw new IllegalArgumentException("未知的URI " + uri);
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}
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// 如果有数据被删除，通知URI变化，以便UI更新和数据同步
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if (count > 0) {
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if (deleteData) {
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getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); // 通知笔记URI变化
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}
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getContext().getContentResolver().notifyChange(uri, null); // 通知特定数据URI变化
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}
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return count; // 返回删除的数据条目数
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}
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// 根据不同的URI请求类型更新数据，返回更新的数据条目数
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@Override
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public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
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int count = 0;
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String id = null;
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SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写的数据库实例
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boolean updateData = false;
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switch (mMatcher.match(uri)) {
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case URI_NOTE:
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// 更新笔记时，增加笔记版本号，以记录笔记的修改历史
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increaseNoteVersion(-1, selection, selectionArgs);
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count = db.update(TABLE.NOTE, values, selection, selectionArgs);
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break;
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case URI_NOTE_ITEM:
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id = uri.getPathSegments().get(1); // 获取URI路径中的笔记ID
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long noteId = Long.valueOf(id);
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// 更新特定ID的笔记，并增加笔记版本号
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increaseNoteVersion(noteId, selection, selectionArgs);
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count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
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+ parseSelection(selection), selectionArgs);
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break;
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case URI_DATA:
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// 更新笔记数据
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count = db.update(TABLE.DATA, values, selection, selectionArgs);
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updateData = true;
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break;
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case URI_DATA_ITEM:
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id = uri.getPathSegments().get(1); // 获取URI路径中的笔记数据ID
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// 更新特定ID的笔记数据
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count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
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+ parseSelection(selection), selectionArgs);
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updateData = true;
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break;
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default:
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// 如果URI请求类型未知，抛出异常以提示错误
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throw new IllegalArgumentException("未知的URI " + uri);
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}
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// 如果有数据被更新，通知URI变化，以便UI更新和数据同步
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if (count > 0) {
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if (updateData) {
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getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); // 通知笔记URI变化
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}
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getContext().getContentResolver().notifyChange(uri, null); // 通知特定数据URI变化
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}
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return count; // 返回更新的数据条目数
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}
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// 解析选择条件字符串，如果存在选择条件，则添加到SQL查询中。用于处理动态SQL查询条件
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private String parseSelection(String selection) {
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// 如果选择条件不为空，则将其添加到SQL查询中
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return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
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}
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// 增加笔记版本号，用于记录笔记的修改历史。每当笔记被更新时，版本号会自动加1
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private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
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StringBuilder sql = new StringBuilder(120);
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sql.append("UPDATE ");
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sql.append(TABLE.NOTE);
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sql.append(" SET ");
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sql.append(NoteColumns.VERSION);
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sql.append("=" + NoteColumns.VERSION + "+1 "); // 将笔记版本号加1
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// 构建WHERE子句，以指定更新哪个笔记
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if (id > 0 || !TextUtils.isEmpty(selection)) {
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sql.append(" WHERE ");
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}
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if (id > 0) {
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sql.append(NoteColumns.ID + "=" + String.valueOf(id)); // 指定更新特定ID的笔记
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}
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if (!TextUtils.isEmpty(selection)) {
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String selectString = id > 0 ? parseSelection(selection) : selection;
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for (String args : selectionArgs) {
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selectString = selectString.replaceFirst("\\?", args); // 替换选择条件中的占位符
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}
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sql.append(selectString);
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}
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// 执行更新操作，增加笔记的版本号
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mHelper.getWritableDatabase().execSQL(sql.toString());
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}
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// 返回URI对应的数据类型。这里未实现，返回null。通常需要根据URI返回相应的MIME类型。
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@Override
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public String getType(Uri uri) {
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// TODO Auto-generated method stub
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return null; // 未实现，返回null
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}
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}
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